kernel_optimize_test/net/sched/sch_fq.c

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pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
/*
* net/sched/sch_fq.c Fair Queue Packet Scheduler (per flow pacing)
*
* Copyright (C) 2013-2015 Eric Dumazet <edumazet@google.com>
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Meant to be mostly used for locally generated traffic :
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
* Fast classification depends on skb->sk being set before reaching us.
* If not, (router workload), we use rxhash as fallback, with 32 bits wide hash.
* All packets belonging to a socket are considered as a 'flow'.
*
* Flows are dynamically allocated and stored in a hash table of RB trees
* They are also part of one Round Robin 'queues' (new or old flows)
*
* Burst avoidance (aka pacing) capability :
*
* Transport (eg TCP) can set in sk->sk_pacing_rate a rate, enqueue a
* bunch of packets, and this packet scheduler adds delay between
* packets to respect rate limitation.
*
* enqueue() :
* - lookup one RB tree (out of 1024 or more) to find the flow.
* If non existent flow, create it, add it to the tree.
* Add skb to the per flow list of skb (fifo).
* - Use a special fifo for high prio packets
*
* dequeue() : serves flows in Round Robin
* Note : When a flow becomes empty, we do not immediately remove it from
* rb trees, for performance reasons (its expected to send additional packets,
* or SLAB cache will reuse socket for another flow)
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
#include <linux/hash.h>
#include <linux/prefetch.h>
#include <linux/vmalloc.h>
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/tcp.h>
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
/*
* Per flow structure, dynamically allocated
*/
struct fq_flow {
struct sk_buff *head; /* list of skbs for this flow : first skb */
union {
struct sk_buff *tail; /* last skb in the list */
unsigned long age; /* jiffies when flow was emptied, for gc */
};
struct rb_node fq_node; /* anchor in fq_root[] trees */
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct sock *sk;
int qlen; /* number of packets in flow queue */
int credit;
u32 socket_hash; /* sk_hash */
struct fq_flow *next; /* next pointer in RR lists, or &detached */
struct rb_node rate_node; /* anchor in q->delayed tree */
u64 time_next_packet;
};
struct fq_flow_head {
struct fq_flow *first;
struct fq_flow *last;
};
struct fq_sched_data {
struct fq_flow_head new_flows;
struct fq_flow_head old_flows;
struct rb_root delayed; /* for rate limited flows */
u64 time_next_delayed_flow;
unsigned long unthrottle_latency_ns;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct fq_flow internal; /* for non classified or high prio packets */
u32 quantum;
u32 initial_quantum;
u32 flow_refill_delay;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
u32 flow_max_rate; /* optional max rate per flow */
u32 flow_plimit; /* max packets per flow */
u32 orphan_mask; /* mask for orphaned skb */
u32 low_rate_threshold;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct rb_root *fq_root;
u8 rate_enable;
u8 fq_trees_log;
u32 flows;
u32 inactive_flows;
u32 throttled_flows;
u64 stat_gc_flows;
u64 stat_internal_packets;
u64 stat_tcp_retrans;
u64 stat_throttled;
u64 stat_flows_plimit;
u64 stat_pkts_too_long;
u64 stat_allocation_errors;
struct qdisc_watchdog watchdog;
};
/* special value to mark a detached flow (not on old/new list) */
static struct fq_flow detached, throttled;
static void fq_flow_set_detached(struct fq_flow *f)
{
f->next = &detached;
f->age = jiffies;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
static bool fq_flow_is_detached(const struct fq_flow *f)
{
return f->next == &detached;
}
static void fq_flow_set_throttled(struct fq_sched_data *q, struct fq_flow *f)
{
struct rb_node **p = &q->delayed.rb_node, *parent = NULL;
while (*p) {
struct fq_flow *aux;
parent = *p;
aux = rb_entry(parent, struct fq_flow, rate_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (f->time_next_packet >= aux->time_next_packet)
p = &parent->rb_right;
else
p = &parent->rb_left;
}
rb_link_node(&f->rate_node, parent, p);
rb_insert_color(&f->rate_node, &q->delayed);
q->throttled_flows++;
q->stat_throttled++;
f->next = &throttled;
if (q->time_next_delayed_flow > f->time_next_packet)
q->time_next_delayed_flow = f->time_next_packet;
}
static struct kmem_cache *fq_flow_cachep __read_mostly;
static void fq_flow_add_tail(struct fq_flow_head *head, struct fq_flow *flow)
{
if (head->first)
head->last->next = flow;
else
head->first = flow;
head->last = flow;
flow->next = NULL;
}
/* limit number of collected flows per round */
#define FQ_GC_MAX 8
#define FQ_GC_AGE (3*HZ)
static bool fq_gc_candidate(const struct fq_flow *f)
{
return fq_flow_is_detached(f) &&
time_after(jiffies, f->age + FQ_GC_AGE);
}
static void fq_gc(struct fq_sched_data *q,
struct rb_root *root,
struct sock *sk)
{
struct fq_flow *f, *tofree[FQ_GC_MAX];
struct rb_node **p, *parent;
int fcnt = 0;
p = &root->rb_node;
parent = NULL;
while (*p) {
parent = *p;
f = rb_entry(parent, struct fq_flow, fq_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (f->sk == sk)
break;
if (fq_gc_candidate(f)) {
tofree[fcnt++] = f;
if (fcnt == FQ_GC_MAX)
break;
}
if (f->sk > sk)
p = &parent->rb_right;
else
p = &parent->rb_left;
}
q->flows -= fcnt;
q->inactive_flows -= fcnt;
q->stat_gc_flows += fcnt;
while (fcnt) {
struct fq_flow *f = tofree[--fcnt];
rb_erase(&f->fq_node, root);
kmem_cache_free(fq_flow_cachep, f);
}
}
static struct fq_flow *fq_classify(struct sk_buff *skb, struct fq_sched_data *q)
{
struct rb_node **p, *parent;
struct sock *sk = skb->sk;
struct rb_root *root;
struct fq_flow *f;
/* warning: no starvation prevention... */
if (unlikely((skb->priority & TC_PRIO_MAX) == TC_PRIO_CONTROL))
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
return &q->internal;
/* SYNACK messages are attached to a TCP_NEW_SYN_RECV request socket
* or a listener (SYNCOOKIE mode)
* 1) request sockets are not full blown,
* they do not contain sk_pacing_rate
* 2) They are not part of a 'flow' yet
* 3) We do not want to rate limit them (eg SYNFLOOD attack),
* especially if the listener set SO_MAX_PACING_RATE
* 4) We pretend they are orphaned
*/
if (!sk || sk_listener(sk)) {
unsigned long hash = skb_get_hash(skb) & q->orphan_mask;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
/* By forcing low order bit to 1, we make sure to not
* collide with a local flow (socket pointers are word aligned)
*/
sk = (struct sock *)((hash << 1) | 1UL);
skb_orphan(skb);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
root = &q->fq_root[hash_ptr(sk, q->fq_trees_log)];
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (q->flows >= (2U << q->fq_trees_log) &&
q->inactive_flows > q->flows/2)
fq_gc(q, root, sk);
p = &root->rb_node;
parent = NULL;
while (*p) {
parent = *p;
f = rb_entry(parent, struct fq_flow, fq_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (f->sk == sk) {
/* socket might have been reallocated, so check
* if its sk_hash is the same.
* It not, we need to refill credit with
* initial quantum
*/
if (unlikely(skb->sk &&
f->socket_hash != sk->sk_hash)) {
f->credit = q->initial_quantum;
f->socket_hash = sk->sk_hash;
f->time_next_packet = 0ULL;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
return f;
}
if (f->sk > sk)
p = &parent->rb_right;
else
p = &parent->rb_left;
}
f = kmem_cache_zalloc(fq_flow_cachep, GFP_ATOMIC | __GFP_NOWARN);
if (unlikely(!f)) {
q->stat_allocation_errors++;
return &q->internal;
}
fq_flow_set_detached(f);
f->sk = sk;
if (skb->sk)
f->socket_hash = sk->sk_hash;
f->credit = q->initial_quantum;
rb_link_node(&f->fq_node, parent, p);
rb_insert_color(&f->fq_node, root);
q->flows++;
q->inactive_flows++;
return f;
}
/* remove one skb from head of flow queue */
static struct sk_buff *fq_dequeue_head(struct Qdisc *sch, struct fq_flow *flow)
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
{
struct sk_buff *skb = flow->head;
if (skb) {
flow->head = skb->next;
skb->next = NULL;
flow->qlen--;
qdisc_qstats_backlog_dec(sch, skb);
sch->q.qlen--;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
return skb;
}
/* We might add in the future detection of retransmits
* For the time being, just return false
*/
static bool skb_is_retransmit(struct sk_buff *skb)
{
return false;
}
/* add skb to flow queue
* flow queue is a linked list, kind of FIFO, except for TCP retransmits
* We special case tcp retransmits to be transmitted before other packets.
* We rely on fact that TCP retransmits are unlikely, so we do not waste
* a separate queue or a pointer.
* head-> [retrans pkt 1]
* [retrans pkt 2]
* [ normal pkt 1]
* [ normal pkt 2]
* [ normal pkt 3]
* tail-> [ normal pkt 4]
*/
static void flow_queue_add(struct fq_flow *flow, struct sk_buff *skb)
{
struct sk_buff *prev, *head = flow->head;
skb->next = NULL;
if (!head) {
flow->head = skb;
flow->tail = skb;
return;
}
if (likely(!skb_is_retransmit(skb))) {
flow->tail->next = skb;
flow->tail = skb;
return;
}
/* This skb is a tcp retransmit,
* find the last retrans packet in the queue
*/
prev = NULL;
while (skb_is_retransmit(head)) {
prev = head;
head = head->next;
if (!head)
break;
}
if (!prev) { /* no rtx packet in queue, become the new head */
skb->next = flow->head;
flow->head = skb;
} else {
if (prev == flow->tail)
flow->tail = skb;
else
skb->next = prev->next;
prev->next = skb;
}
}
static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
{
struct fq_sched_data *q = qdisc_priv(sch);
struct fq_flow *f;
if (unlikely(sch->q.qlen >= sch->limit))
return qdisc_drop(skb, sch, to_free);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
f = fq_classify(skb, q);
if (unlikely(f->qlen >= q->flow_plimit && f != &q->internal)) {
q->stat_flows_plimit++;
return qdisc_drop(skb, sch, to_free);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
f->qlen++;
if (skb_is_retransmit(skb))
q->stat_tcp_retrans++;
qdisc_qstats_backlog_inc(sch, skb);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (fq_flow_is_detached(f)) {
tcp: internal implementation for pacing BBR congestion control depends on pacing, and pacing is currently handled by sch_fq packet scheduler for performance reasons, and also because implemening pacing with FQ was convenient to truly avoid bursts. However there are many cases where this packet scheduler constraint is not practical. - Many linux hosts are not focusing on handling thousands of TCP flows in the most efficient way. - Some routers use fq_codel or other AQM, but still would like to use BBR for the few TCP flows they initiate/terminate. This patch implements an automatic fallback to internal pacing. Pacing is requested either by BBR or use of SO_MAX_PACING_RATE option. If sch_fq happens to be in the egress path, pacing is delegated to the qdisc, otherwise pacing is done by TCP itself. One advantage of pacing from TCP stack is to get more precise rtt estimations, and less work done from TX completion, since TCP Small queue limits are not generally hit. Setups with single TX queue but many cpus might even benefit from this. Note that unlike sch_fq, we do not take into account header sizes. Taking care of these headers would add additional complexity for no practical differences in behavior. Some performance numbers using 800 TCP_STREAM flows rate limited to ~48 Mbit per second on 40Gbit NIC. If MQ+pfifo_fast is used on the NIC : $ sar -n DEV 1 5 | grep eth 14:48:44 eth0 725743.00 2932134.00 46776.76 4335184.68 0.00 0.00 1.00 14:48:45 eth0 725349.00 2932112.00 46751.86 4335158.90 0.00 0.00 0.00 14:48:46 eth0 725101.00 2931153.00 46735.07 4333748.63 0.00 0.00 0.00 14:48:47 eth0 725099.00 2931161.00 46735.11 4333760.44 0.00 0.00 1.00 14:48:48 eth0 725160.00 2931731.00 46738.88 4334606.07 0.00 0.00 0.00 Average: eth0 725290.40 2931658.20 46747.54 4334491.74 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 4 0 0 259825920 45644 2708324 0 0 21 2 247 98 0 0 100 0 0 4 0 0 259823744 45644 2708356 0 0 0 0 2400825 159843 0 19 81 0 0 0 0 0 259824208 45644 2708072 0 0 0 0 2407351 159929 0 19 81 0 0 1 0 0 259824592 45644 2708128 0 0 0 0 2405183 160386 0 19 80 0 0 1 0 0 259824272 45644 2707868 0 0 0 32 2396361 158037 0 19 81 0 0 Now use MQ+FQ : lpaa23:~# echo fq >/proc/sys/net/core/default_qdisc lpaa23:~# tc qdisc replace dev eth0 root mq $ sar -n DEV 1 5 | grep eth 14:49:57 eth0 678614.00 2727930.00 43739.13 4033279.14 0.00 0.00 0.00 14:49:58 eth0 677620.00 2723971.00 43674.69 4027429.62 0.00 0.00 1.00 14:49:59 eth0 676396.00 2719050.00 43596.83 4020125.02 0.00 0.00 0.00 14:50:00 eth0 675197.00 2714173.00 43518.62 4012938.90 0.00 0.00 1.00 14:50:01 eth0 676388.00 2719063.00 43595.47 4020171.64 0.00 0.00 0.00 Average: eth0 676843.00 2720837.40 43624.95 4022788.86 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 259832240 46008 2710912 0 0 21 2 223 192 0 1 99 0 0 1 0 0 259832896 46008 2710744 0 0 0 0 1702206 198078 0 17 82 0 0 0 0 0 259830272 46008 2710596 0 0 0 0 1696340 197756 1 17 83 0 0 4 0 0 259829168 46024 2710584 0 0 16 0 1688472 197158 1 17 82 0 0 3 0 0 259830224 46024 2710408 0 0 0 0 1692450 197212 0 18 82 0 0 As expected, number of interrupts per second is very different. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Van Jacobson <vanj@google.com> Cc: Jerry Chu <hkchu@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-16 19:24:36 +08:00
struct sock *sk = skb->sk;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
fq_flow_add_tail(&q->new_flows, f);
if (time_after(jiffies, f->age + q->flow_refill_delay))
f->credit = max_t(u32, f->credit, q->quantum);
tcp: internal implementation for pacing BBR congestion control depends on pacing, and pacing is currently handled by sch_fq packet scheduler for performance reasons, and also because implemening pacing with FQ was convenient to truly avoid bursts. However there are many cases where this packet scheduler constraint is not practical. - Many linux hosts are not focusing on handling thousands of TCP flows in the most efficient way. - Some routers use fq_codel or other AQM, but still would like to use BBR for the few TCP flows they initiate/terminate. This patch implements an automatic fallback to internal pacing. Pacing is requested either by BBR or use of SO_MAX_PACING_RATE option. If sch_fq happens to be in the egress path, pacing is delegated to the qdisc, otherwise pacing is done by TCP itself. One advantage of pacing from TCP stack is to get more precise rtt estimations, and less work done from TX completion, since TCP Small queue limits are not generally hit. Setups with single TX queue but many cpus might even benefit from this. Note that unlike sch_fq, we do not take into account header sizes. Taking care of these headers would add additional complexity for no practical differences in behavior. Some performance numbers using 800 TCP_STREAM flows rate limited to ~48 Mbit per second on 40Gbit NIC. If MQ+pfifo_fast is used on the NIC : $ sar -n DEV 1 5 | grep eth 14:48:44 eth0 725743.00 2932134.00 46776.76 4335184.68 0.00 0.00 1.00 14:48:45 eth0 725349.00 2932112.00 46751.86 4335158.90 0.00 0.00 0.00 14:48:46 eth0 725101.00 2931153.00 46735.07 4333748.63 0.00 0.00 0.00 14:48:47 eth0 725099.00 2931161.00 46735.11 4333760.44 0.00 0.00 1.00 14:48:48 eth0 725160.00 2931731.00 46738.88 4334606.07 0.00 0.00 0.00 Average: eth0 725290.40 2931658.20 46747.54 4334491.74 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 4 0 0 259825920 45644 2708324 0 0 21 2 247 98 0 0 100 0 0 4 0 0 259823744 45644 2708356 0 0 0 0 2400825 159843 0 19 81 0 0 0 0 0 259824208 45644 2708072 0 0 0 0 2407351 159929 0 19 81 0 0 1 0 0 259824592 45644 2708128 0 0 0 0 2405183 160386 0 19 80 0 0 1 0 0 259824272 45644 2707868 0 0 0 32 2396361 158037 0 19 81 0 0 Now use MQ+FQ : lpaa23:~# echo fq >/proc/sys/net/core/default_qdisc lpaa23:~# tc qdisc replace dev eth0 root mq $ sar -n DEV 1 5 | grep eth 14:49:57 eth0 678614.00 2727930.00 43739.13 4033279.14 0.00 0.00 0.00 14:49:58 eth0 677620.00 2723971.00 43674.69 4027429.62 0.00 0.00 1.00 14:49:59 eth0 676396.00 2719050.00 43596.83 4020125.02 0.00 0.00 0.00 14:50:00 eth0 675197.00 2714173.00 43518.62 4012938.90 0.00 0.00 1.00 14:50:01 eth0 676388.00 2719063.00 43595.47 4020171.64 0.00 0.00 0.00 Average: eth0 676843.00 2720837.40 43624.95 4022788.86 0.00 0.00 0.40 $ vmstat 1 5 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 259832240 46008 2710912 0 0 21 2 223 192 0 1 99 0 0 1 0 0 259832896 46008 2710744 0 0 0 0 1702206 198078 0 17 82 0 0 0 0 0 259830272 46008 2710596 0 0 0 0 1696340 197756 1 17 83 0 0 4 0 0 259829168 46024 2710584 0 0 16 0 1688472 197158 1 17 82 0 0 3 0 0 259830224 46024 2710408 0 0 0 0 1692450 197212 0 18 82 0 0 As expected, number of interrupts per second is very different. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Cc: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Van Jacobson <vanj@google.com> Cc: Jerry Chu <hkchu@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-16 19:24:36 +08:00
if (sk && q->rate_enable) {
if (unlikely(smp_load_acquire(&sk->sk_pacing_status) !=
SK_PACING_FQ))
smp_store_release(&sk->sk_pacing_status,
SK_PACING_FQ);
}
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
q->inactive_flows--;
}
/* Note: this overwrites f->age */
flow_queue_add(f, skb);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (unlikely(f == &q->internal)) {
q->stat_internal_packets++;
}
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
static void fq_check_throttled(struct fq_sched_data *q, u64 now)
{
unsigned long sample;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct rb_node *p;
if (q->time_next_delayed_flow > now)
return;
/* Update unthrottle latency EWMA.
* This is cheap and can help diagnosing timer/latency problems.
*/
sample = (unsigned long)(now - q->time_next_delayed_flow);
q->unthrottle_latency_ns -= q->unthrottle_latency_ns >> 3;
q->unthrottle_latency_ns += sample >> 3;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
q->time_next_delayed_flow = ~0ULL;
while ((p = rb_first(&q->delayed)) != NULL) {
struct fq_flow *f = rb_entry(p, struct fq_flow, rate_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (f->time_next_packet > now) {
q->time_next_delayed_flow = f->time_next_packet;
break;
}
rb_erase(p, &q->delayed);
q->throttled_flows--;
fq_flow_add_tail(&q->old_flows, f);
}
}
static struct sk_buff *fq_dequeue(struct Qdisc *sch)
{
struct fq_sched_data *q = qdisc_priv(sch);
u64 now = ktime_get_ns();
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct fq_flow_head *head;
struct sk_buff *skb;
struct fq_flow *f;
u32 rate, plen;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
skb = fq_dequeue_head(sch, &q->internal);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (skb)
goto out;
fq_check_throttled(q, now);
begin:
head = &q->new_flows;
if (!head->first) {
head = &q->old_flows;
if (!head->first) {
if (q->time_next_delayed_flow != ~0ULL)
qdisc_watchdog_schedule_ns(&q->watchdog,
q->time_next_delayed_flow);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
return NULL;
}
}
f = head->first;
if (f->credit <= 0) {
f->credit += q->quantum;
head->first = f->next;
fq_flow_add_tail(&q->old_flows, f);
goto begin;
}
skb = f->head;
if (unlikely(skb && now < f->time_next_packet &&
!skb_is_tcp_pure_ack(skb))) {
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
head->first = f->next;
fq_flow_set_throttled(q, f);
goto begin;
}
skb = fq_dequeue_head(sch, f);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (!skb) {
head->first = f->next;
/* force a pass through old_flows to prevent starvation */
if ((head == &q->new_flows) && q->old_flows.first) {
fq_flow_add_tail(&q->old_flows, f);
} else {
fq_flow_set_detached(f);
q->inactive_flows++;
}
goto begin;
}
prefetch(&skb->end);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
f->credit -= qdisc_pkt_len(skb);
if (!q->rate_enable)
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
goto out;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
/* Do not pace locally generated ack packets */
if (skb_is_tcp_pure_ack(skb))
goto out;
rate = q->flow_max_rate;
if (skb->sk)
rate = min(skb->sk->sk_pacing_rate, rate);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (rate <= q->low_rate_threshold) {
f->credit = 0;
plen = qdisc_pkt_len(skb);
} else {
plen = max(qdisc_pkt_len(skb), q->quantum);
if (f->credit > 0)
goto out;
}
if (rate != ~0U) {
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
u64 len = (u64)plen * NSEC_PER_SEC;
if (likely(rate))
do_div(len, rate);
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
/* Since socket rate can change later,
* clamp the delay to 1 second.
* Really, providers of too big packets should be fixed !
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
*/
if (unlikely(len > NSEC_PER_SEC)) {
len = NSEC_PER_SEC;
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
q->stat_pkts_too_long++;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
/* Account for schedule/timers drifts.
* f->time_next_packet was set when prior packet was sent,
* and current time (@now) can be too late by tens of us.
*/
if (f->time_next_packet)
len -= min(len/2, now - f->time_next_packet);
pkt_sched: fq: rate limiting improvements FQ rate limiting suffers from two problems, reported by Steinar : 1) FQ enforces a delay when flow quantum is exhausted in order to reduce cpu overhead. But if packets are small, current delay computation is slightly wrong, and observed rates can be too high. Steinar had this problem because he disabled TSO and GSO, and default FQ quantum is 2*1514. (Of course, I wish recent TSO auto sizing changes will help to not having to disable TSO in the first place) 2) maxrate was not used for forwarded flows (skbs not attached to a socket) Tested: tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit netperf -H lpq84 -l 1000 & sleep 10 ; tc -s qdisc show dev eth0 qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024 quantum 3028 initial_quantum 15140 maxrate 8000Kbit Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0) rate 7831Kbit 653pps backlog 7570b 5p requeues 0 44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns 0 gc, 0 highprio, 5545 throttled lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12 09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068> 09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812> 09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071> 09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815> 09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074> 09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818> 09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077> 09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821> Reported-by: Steinar H. Gunderson <sesse@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-02 00:10:16 +08:00
f->time_next_packet = now + len;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
out:
qdisc_bstats_update(sch, skb);
return skb;
}
static void fq_flow_purge(struct fq_flow *flow)
{
rtnl_kfree_skbs(flow->head, flow->tail);
flow->head = NULL;
flow->qlen = 0;
}
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
static void fq_reset(struct Qdisc *sch)
{
struct fq_sched_data *q = qdisc_priv(sch);
struct rb_root *root;
struct rb_node *p;
struct fq_flow *f;
unsigned int idx;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
sch->q.qlen = 0;
sch->qstats.backlog = 0;
fq_flow_purge(&q->internal);
if (!q->fq_root)
return;
for (idx = 0; idx < (1U << q->fq_trees_log); idx++) {
root = &q->fq_root[idx];
while ((p = rb_first(root)) != NULL) {
f = rb_entry(p, struct fq_flow, fq_node);
rb_erase(p, root);
fq_flow_purge(f);
kmem_cache_free(fq_flow_cachep, f);
}
}
q->new_flows.first = NULL;
q->old_flows.first = NULL;
q->delayed = RB_ROOT;
q->flows = 0;
q->inactive_flows = 0;
q->throttled_flows = 0;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
}
static void fq_rehash(struct fq_sched_data *q,
struct rb_root *old_array, u32 old_log,
struct rb_root *new_array, u32 new_log)
{
struct rb_node *op, **np, *parent;
struct rb_root *oroot, *nroot;
struct fq_flow *of, *nf;
int fcnt = 0;
u32 idx;
for (idx = 0; idx < (1U << old_log); idx++) {
oroot = &old_array[idx];
while ((op = rb_first(oroot)) != NULL) {
rb_erase(op, oroot);
of = rb_entry(op, struct fq_flow, fq_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (fq_gc_candidate(of)) {
fcnt++;
kmem_cache_free(fq_flow_cachep, of);
continue;
}
nroot = &new_array[hash_ptr(of->sk, new_log)];
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
np = &nroot->rb_node;
parent = NULL;
while (*np) {
parent = *np;
nf = rb_entry(parent, struct fq_flow, fq_node);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
BUG_ON(nf->sk == of->sk);
if (nf->sk > of->sk)
np = &parent->rb_right;
else
np = &parent->rb_left;
}
rb_link_node(&of->fq_node, parent, np);
rb_insert_color(&of->fq_node, nroot);
}
}
q->flows -= fcnt;
q->inactive_flows -= fcnt;
q->stat_gc_flows += fcnt;
}
static void fq_free(void *addr)
{
kvfree(addr);
}
static int fq_resize(struct Qdisc *sch, u32 log)
{
struct fq_sched_data *q = qdisc_priv(sch);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
struct rb_root *array;
void *old_fq_root;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
u32 idx;
if (q->fq_root && log == q->fq_trees_log)
return 0;
/* If XPS was setup, we can allocate memory on right NUMA node */
mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic __GFP_REPEAT was designed to allow retry-but-eventually-fail semantic to the page allocator. This has been true but only for allocations requests larger than PAGE_ALLOC_COSTLY_ORDER. It has been always ignored for smaller sizes. This is a bit unfortunate because there is no way to express the same semantic for those requests and they are considered too important to fail so they might end up looping in the page allocator for ever, similarly to GFP_NOFAIL requests. Now that the whole tree has been cleaned up and accidental or misled usage of __GFP_REPEAT flag has been removed for !costly requests we can give the original flag a better name and more importantly a more useful semantic. Let's rename it to __GFP_RETRY_MAYFAIL which tells the user that the allocator would try really hard but there is no promise of a success. This will work independent of the order and overrides the default allocator behavior. Page allocator users have several levels of guarantee vs. cost options (take GFP_KERNEL as an example) - GFP_KERNEL & ~__GFP_RECLAIM - optimistic allocation without _any_ attempt to free memory at all. The most light weight mode which even doesn't kick the background reclaim. Should be used carefully because it might deplete the memory and the next user might hit the more aggressive reclaim - GFP_KERNEL & ~__GFP_DIRECT_RECLAIM (or GFP_NOWAIT)- optimistic allocation without any attempt to free memory from the current context but can wake kswapd to reclaim memory if the zone is below the low watermark. Can be used from either atomic contexts or when the request is a performance optimization and there is another fallback for a slow path. - (GFP_KERNEL|__GFP_HIGH) & ~__GFP_DIRECT_RECLAIM (aka GFP_ATOMIC) - non sleeping allocation with an expensive fallback so it can access some portion of memory reserves. Usually used from interrupt/bh context with an expensive slow path fallback. - GFP_KERNEL - both background and direct reclaim are allowed and the _default_ page allocator behavior is used. That means that !costly allocation requests are basically nofail but there is no guarantee of that behavior so failures have to be checked properly by callers (e.g. OOM killer victim is allowed to fail currently). - GFP_KERNEL | __GFP_NORETRY - overrides the default allocator behavior and all allocation requests fail early rather than cause disruptive reclaim (one round of reclaim in this implementation). The OOM killer is not invoked. - GFP_KERNEL | __GFP_RETRY_MAYFAIL - overrides the default allocator behavior and all allocation requests try really hard. The request will fail if the reclaim cannot make any progress. The OOM killer won't be triggered. - GFP_KERNEL | __GFP_NOFAIL - overrides the default allocator behavior and all allocation requests will loop endlessly until they succeed. This might be really dangerous especially for larger orders. Existing users of __GFP_REPEAT are changed to __GFP_RETRY_MAYFAIL because they already had their semantic. No new users are added. __alloc_pages_slowpath is changed to bail out for __GFP_RETRY_MAYFAIL if there is no progress and we have already passed the OOM point. This means that all the reclaim opportunities have been exhausted except the most disruptive one (the OOM killer) and a user defined fallback behavior is more sensible than keep retrying in the page allocator. [akpm@linux-foundation.org: fix arch/sparc/kernel/mdesc.c] [mhocko@suse.com: semantic fix] Link: http://lkml.kernel.org/r/20170626123847.GM11534@dhcp22.suse.cz [mhocko@kernel.org: address other thing spotted by Vlastimil] Link: http://lkml.kernel.org/r/20170626124233.GN11534@dhcp22.suse.cz Link: http://lkml.kernel.org/r/20170623085345.11304-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Alex Belits <alex.belits@cavium.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: David Daney <david.daney@cavium.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: NeilBrown <neilb@suse.com> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-13 05:36:45 +08:00
array = kvmalloc_node(sizeof(struct rb_root) << log, GFP_KERNEL | __GFP_RETRY_MAYFAIL,
netdev_queue_numa_node_read(sch->dev_queue));
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (!array)
return -ENOMEM;
for (idx = 0; idx < (1U << log); idx++)
array[idx] = RB_ROOT;
sch_tree_lock(sch);
old_fq_root = q->fq_root;
if (old_fq_root)
fq_rehash(q, old_fq_root, q->fq_trees_log, array, log);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
q->fq_root = array;
q->fq_trees_log = log;
sch_tree_unlock(sch);
fq_free(old_fq_root);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
return 0;
}
static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = {
[TCA_FQ_PLIMIT] = { .type = NLA_U32 },
[TCA_FQ_FLOW_PLIMIT] = { .type = NLA_U32 },
[TCA_FQ_QUANTUM] = { .type = NLA_U32 },
[TCA_FQ_INITIAL_QUANTUM] = { .type = NLA_U32 },
[TCA_FQ_RATE_ENABLE] = { .type = NLA_U32 },
[TCA_FQ_FLOW_DEFAULT_RATE] = { .type = NLA_U32 },
[TCA_FQ_FLOW_MAX_RATE] = { .type = NLA_U32 },
[TCA_FQ_BUCKETS_LOG] = { .type = NLA_U32 },
[TCA_FQ_FLOW_REFILL_DELAY] = { .type = NLA_U32 },
[TCA_FQ_LOW_RATE_THRESHOLD] = { .type = NLA_U32 },
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
};
static int fq_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
{
struct fq_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_FQ_MAX + 1];
int err, drop_count = 0;
unsigned drop_len = 0;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
u32 fq_log;
if (!opt)
return -EINVAL;
err = nla_parse_nested(tb, TCA_FQ_MAX, opt, fq_policy, NULL);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (err < 0)
return err;
sch_tree_lock(sch);
fq_log = q->fq_trees_log;
if (tb[TCA_FQ_BUCKETS_LOG]) {
u32 nval = nla_get_u32(tb[TCA_FQ_BUCKETS_LOG]);
if (nval >= 1 && nval <= ilog2(256*1024))
fq_log = nval;
else
err = -EINVAL;
}
if (tb[TCA_FQ_PLIMIT])
sch->limit = nla_get_u32(tb[TCA_FQ_PLIMIT]);
if (tb[TCA_FQ_FLOW_PLIMIT])
q->flow_plimit = nla_get_u32(tb[TCA_FQ_FLOW_PLIMIT]);
if (tb[TCA_FQ_QUANTUM]) {
u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
if (quantum > 0)
q->quantum = quantum;
else
err = -EINVAL;
}
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (tb[TCA_FQ_INITIAL_QUANTUM])
q->initial_quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (tb[TCA_FQ_FLOW_DEFAULT_RATE])
pr_warn_ratelimited("sch_fq: defrate %u ignored.\n",
nla_get_u32(tb[TCA_FQ_FLOW_DEFAULT_RATE]));
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (tb[TCA_FQ_FLOW_MAX_RATE])
q->flow_max_rate = nla_get_u32(tb[TCA_FQ_FLOW_MAX_RATE]);
if (tb[TCA_FQ_LOW_RATE_THRESHOLD])
q->low_rate_threshold =
nla_get_u32(tb[TCA_FQ_LOW_RATE_THRESHOLD]);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (tb[TCA_FQ_RATE_ENABLE]) {
u32 enable = nla_get_u32(tb[TCA_FQ_RATE_ENABLE]);
if (enable <= 1)
q->rate_enable = enable;
else
err = -EINVAL;
}
if (tb[TCA_FQ_FLOW_REFILL_DELAY]) {
u32 usecs_delay = nla_get_u32(tb[TCA_FQ_FLOW_REFILL_DELAY]) ;
q->flow_refill_delay = usecs_to_jiffies(usecs_delay);
}
if (tb[TCA_FQ_ORPHAN_MASK])
q->orphan_mask = nla_get_u32(tb[TCA_FQ_ORPHAN_MASK]);
if (!err) {
sch_tree_unlock(sch);
err = fq_resize(sch, fq_log);
sch_tree_lock(sch);
}
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = fq_dequeue(sch);
if (!skb)
break;
drop_len += qdisc_pkt_len(skb);
rtnl_kfree_skbs(skb, skb);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
drop_count++;
}
qdisc_tree_reduce_backlog(sch, drop_count, drop_len);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
sch_tree_unlock(sch);
return err;
}
static void fq_destroy(struct Qdisc *sch)
{
struct fq_sched_data *q = qdisc_priv(sch);
fq_reset(sch);
fq_free(q->fq_root);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
qdisc_watchdog_cancel(&q->watchdog);
}
static int fq_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
{
struct fq_sched_data *q = qdisc_priv(sch);
int err;
sch->limit = 10000;
q->flow_plimit = 100;
q->quantum = 2 * psched_mtu(qdisc_dev(sch));
q->initial_quantum = 10 * psched_mtu(qdisc_dev(sch));
q->flow_refill_delay = msecs_to_jiffies(40);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
q->flow_max_rate = ~0U;
q->time_next_delayed_flow = ~0ULL;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
q->rate_enable = 1;
q->new_flows.first = NULL;
q->old_flows.first = NULL;
q->delayed = RB_ROOT;
q->fq_root = NULL;
q->fq_trees_log = ilog2(1024);
q->orphan_mask = 1024 - 1;
q->low_rate_threshold = 550000 / 8;
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
qdisc_watchdog_init(&q->watchdog, sch);
if (opt)
err = fq_change(sch, opt, extack);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
else
err = fq_resize(sch, q->fq_trees_log);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
return err;
}
static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct fq_sched_data *q = qdisc_priv(sch);
struct nlattr *opts;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (opts == NULL)
goto nla_put_failure;
/* TCA_FQ_FLOW_DEFAULT_RATE is not used anymore */
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
if (nla_put_u32(skb, TCA_FQ_PLIMIT, sch->limit) ||
nla_put_u32(skb, TCA_FQ_FLOW_PLIMIT, q->flow_plimit) ||
nla_put_u32(skb, TCA_FQ_QUANTUM, q->quantum) ||
nla_put_u32(skb, TCA_FQ_INITIAL_QUANTUM, q->initial_quantum) ||
nla_put_u32(skb, TCA_FQ_RATE_ENABLE, q->rate_enable) ||
nla_put_u32(skb, TCA_FQ_FLOW_MAX_RATE, q->flow_max_rate) ||
nla_put_u32(skb, TCA_FQ_FLOW_REFILL_DELAY,
jiffies_to_usecs(q->flow_refill_delay)) ||
nla_put_u32(skb, TCA_FQ_ORPHAN_MASK, q->orphan_mask) ||
nla_put_u32(skb, TCA_FQ_LOW_RATE_THRESHOLD,
q->low_rate_threshold) ||
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log))
goto nla_put_failure;
return nla_nest_end(skb, opts);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
nla_put_failure:
return -1;
}
static int fq_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
struct fq_sched_data *q = qdisc_priv(sch);
struct tc_fq_qd_stats st;
sch_tree_lock(sch);
st.gc_flows = q->stat_gc_flows;
st.highprio_packets = q->stat_internal_packets;
st.tcp_retrans = q->stat_tcp_retrans;
st.throttled = q->stat_throttled;
st.flows_plimit = q->stat_flows_plimit;
st.pkts_too_long = q->stat_pkts_too_long;
st.allocation_errors = q->stat_allocation_errors;
st.time_next_delayed_flow = q->time_next_delayed_flow - ktime_get_ns();
st.flows = q->flows;
st.inactive_flows = q->inactive_flows;
st.throttled_flows = q->throttled_flows;
st.unthrottle_latency_ns = min_t(unsigned long,
q->unthrottle_latency_ns, ~0U);
sch_tree_unlock(sch);
pkt_sched: fq: Fair Queue packet scheduler - Uses perfect flow match (not stochastic hash like SFQ/FQ_codel) - Uses the new_flow/old_flow separation from FQ_codel - New flows get an initial credit allowing IW10 without added delay. - Special FIFO queue for high prio packets (no need for PRIO + FQ) - Uses a hash table of RB trees to locate the flows at enqueue() time - Smart on demand gc (at enqueue() time, RB tree lookup evicts old unused flows) - Dynamic memory allocations. - Designed to allow millions of concurrent flows per Qdisc. - Small memory footprint : ~8K per Qdisc, and 104 bytes per flow. - Single high resolution timer for throttled flows (if any). - One RB tree to link throttled flows. - Ability to have a max rate per flow. We might add a socket option to add per socket limitation. Attempts have been made to add TCP pacing in TCP stack, but this seems to add complex code to an already complex stack. TCP pacing is welcomed for flows having idle times, as the cwnd permits TCP stack to queue a possibly large number of packets. This removes the 'slow start after idle' choice, hitting badly large BDP flows, and applications delivering chunks of data as video streams. Nicely spaced packets : Here interface is 10Gbit, but flow bottleneck is ~20Mbit cwin is big, yet FQ avoids the typical bursts generated by TCP (as in netperf TCP_RR -- -r 100000,100000) 15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115> 15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115> 15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115> 15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115> 15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115> 15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115> 15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115> 15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805> 15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115> 15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> 15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115> TCP timestamps show that most packets from B were queued in the same ms timeframe (TSval 1159799{3,4}), but FQ managed to send them right in time to avoid a big burst. In slow start or steady state, very few packets are throttled [1] FQ gets a bunch of tunables as : limit : max number of packets on whole Qdisc (default 10000) flow_limit : max number of packets per flow (default 100) quantum : the credit per RR round (default is 2 MTU) initial_quantum : initial credit for new flows (default is 10 MTU) maxrate : max per flow rate (default : unlimited) buckets : number of RB trees (default : 1024) in hash table. (consumes 8 bytes per bucket) [no]pacing : disable/enable pacing (default is enable) All of them can be changed on a live qdisc. $ tc qd add dev eth0 root fq help Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ] [ quantum BYTES ] [ initial_quantum BYTES ] [ maxrate RATE ] [ buckets NUMBER ] [ [no]pacing ] $ tc -s -d qd qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140 Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14) backlog 0b 0p requeues 14 511 flows, 511 inactive, 0 throttled 110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit [1] Except if initial srtt is overestimated, as if using cached srtt in tcp metrics. We'll provide a fix for this issue. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-30 06:49:55 +08:00
return gnet_stats_copy_app(d, &st, sizeof(st));
}
static struct Qdisc_ops fq_qdisc_ops __read_mostly = {
.id = "fq",
.priv_size = sizeof(struct fq_sched_data),
.enqueue = fq_enqueue,
.dequeue = fq_dequeue,
.peek = qdisc_peek_dequeued,
.init = fq_init,
.reset = fq_reset,
.destroy = fq_destroy,
.change = fq_change,
.dump = fq_dump,
.dump_stats = fq_dump_stats,
.owner = THIS_MODULE,
};
static int __init fq_module_init(void)
{
int ret;
fq_flow_cachep = kmem_cache_create("fq_flow_cache",
sizeof(struct fq_flow),
0, 0, NULL);
if (!fq_flow_cachep)
return -ENOMEM;
ret = register_qdisc(&fq_qdisc_ops);
if (ret)
kmem_cache_destroy(fq_flow_cachep);
return ret;
}
static void __exit fq_module_exit(void)
{
unregister_qdisc(&fq_qdisc_ops);
kmem_cache_destroy(fq_flow_cachep);
}
module_init(fq_module_init)
module_exit(fq_module_exit)
MODULE_AUTHOR("Eric Dumazet");
MODULE_LICENSE("GPL");