tmp_suning_uos_patched/net/core
Benjamin Poirier cdb3f4a31b net: Do not enable tx-nocache-copy by default
There are many cases where this feature does not improve performance or even
reduces it.

For example, here are the results from tests that I've run using 3.12.6 on one
Intel Xeon W3565 and one i7 920 connected by ixgbe adapters. The results are
from the Xeon, but they're similar on the i7. All numbers report the
mean±stddev over 10 runs of 10s.

1) latency tests similar to what is described in "c6e1a0d net: Allow no-cache
copy from user on transmit"
There is no statistically significant difference between tx-nocache-copy
on/off.
nic irqs spread out (one queue per cpu)

200x netperf -r 1400,1
tx-nocache-copy off
        692000±1000 tps
        50/90/95/99% latency (us): 275±2/643.8±0.4/799±1/2474.4±0.3
tx-nocache-copy on
        693000±1000 tps
        50/90/95/99% latency (us): 274±1/644.1±0.7/800±2/2474.5±0.7

200x netperf -r 14000,14000
tx-nocache-copy off
        86450±80 tps
        50/90/95/99% latency (us): 334.37±0.02/838±1/2100±20/3990±40
tx-nocache-copy on
        86110±60 tps
        50/90/95/99% latency (us): 334.28±0.01/837±2/2110±20/3990±20

2) single stream throughput tests
tx-nocache-copy leads to higher service demand

                        throughput  cpu0        cpu1        demand
                        (Gb/s)      (Gcycle)    (Gcycle)    (cycle/B)

nic irqs and netperf on cpu0 (1x netperf -T0,0 -t omni -- -d send)

tx-nocache-copy off     9402±5      9.4±0.2                 0.80±0.01
tx-nocache-copy on      9403±3      9.85±0.04               0.838±0.004

nic irqs on cpu0, netperf on cpu1 (1x netperf -T1,1 -t omni -- -d send)

tx-nocache-copy off     9401±5      5.83±0.03   5.0±0.1     0.923±0.007
tx-nocache-copy on      9404±2      5.74±0.03   5.523±0.009 0.958±0.002

As a second example, here are some results from Eric Dumazet with latest
net-next.
tx-nocache-copy also leads to higher service demand

(cpu is Intel(R) Xeon(R) CPU X5660  @ 2.80GHz)

lpq83:~# ./ethtool -K eth0 tx-nocache-copy on
lpq83:~# perf stat ./netperf -H lpq84 -c
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to lpq84.prod.google.com () port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % U      us/KB   us/KB

 87380  16384  16384    10.00      9407.44   2.50     -1.00    0.522   -1.000

 Performance counter stats for './netperf -H lpq84 -c':

       4282.648396 task-clock                #    0.423 CPUs utilized
             9,348 context-switches          #    0.002 M/sec
                88 CPU-migrations            #    0.021 K/sec
               355 page-faults               #    0.083 K/sec
    11,812,797,651 cycles                    #    2.758 GHz                     [82.79%]
     9,020,522,817 stalled-cycles-frontend   #   76.36% frontend cycles idle    [82.54%]
     4,579,889,681 stalled-cycles-backend    #   38.77% backend  cycles idle    [67.33%]
     6,053,172,792 instructions              #    0.51  insns per cycle
                                             #    1.49  stalled cycles per insn [83.64%]
       597,275,583 branches                  #  139.464 M/sec                   [83.70%]
         8,960,541 branch-misses             #    1.50% of all branches         [83.65%]

      10.128990264 seconds time elapsed

lpq83:~# ./ethtool -K eth0 tx-nocache-copy off
lpq83:~# perf stat ./netperf -H lpq84 -c
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to lpq84.prod.google.com () port 0 AF_INET
Recv   Send    Send                          Utilization       Service Demand
Socket Socket  Message  Elapsed              Send     Recv     Send    Recv
Size   Size    Size     Time     Throughput  local    remote   local   remote
bytes  bytes   bytes    secs.    10^6bits/s  % S      % U      us/KB   us/KB

 87380  16384  16384    10.00      9412.45   2.15     -1.00    0.449   -1.000

 Performance counter stats for './netperf -H lpq84 -c':

       2847.375441 task-clock                #    0.281 CPUs utilized
            11,632 context-switches          #    0.004 M/sec
                49 CPU-migrations            #    0.017 K/sec
               354 page-faults               #    0.124 K/sec
     7,646,889,749 cycles                    #    2.686 GHz                     [83.34%]
     6,115,050,032 stalled-cycles-frontend   #   79.97% frontend cycles idle    [83.31%]
     1,726,460,071 stalled-cycles-backend    #   22.58% backend  cycles idle    [66.55%]
     2,079,702,453 instructions              #    0.27  insns per cycle
                                             #    2.94  stalled cycles per insn [83.22%]
       363,773,213 branches                  #  127.757 M/sec                   [83.29%]
         4,242,732 branch-misses             #    1.17% of all branches         [83.51%]

      10.128449949 seconds time elapsed

CC: Tom Herbert <therbert@google.com>
Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-07 16:20:19 -05:00
..
datagram.c net, datagram: fix the incorrect comment in zerocopy_sg_from_iovec() 2013-10-29 00:19:04 -04:00
dev_addr_lists.c net: remove dead code for add/del multiple 2013-12-17 15:14:04 -05:00
dev_ioctl.c net_tstamp: Add SIOCGHWTSTAMP ioctl to match SIOCSHWTSTAMP 2013-11-19 19:07:21 +00:00
dev.c net: Do not enable tx-nocache-copy by default 2014-01-07 16:20:19 -05:00
drop_monitor.c net: drop_monitor: fix the value of maxattr 2013-12-09 21:10:38 -05:00
dst.c
ethtool.c net: Add layer 2 hardware acceleration operations for macvlan devices 2013-11-07 19:11:41 -05:00
fib_rules.c net: Fix "ip rule delete table 256" 2013-11-08 14:53:10 -05:00
filter.c net: fix unsafe set_memory_rw from softirq 2013-10-07 15:16:45 -04:00
flow_dissector.c net: Change skb_get_rxhash to skb_get_hash 2013-12-17 16:36:21 -05:00
flow.c net: delete __cpuinit usage from all net files 2013-07-14 19:36:58 -04:00
gen_estimator.c net_sched: add 64bit rate estimators 2013-06-11 02:51:03 -07:00
gen_stats.c net_sched: add 64bit rate estimators 2013-06-11 02:51:03 -07:00
iovec.c net: rework recvmsg handler msg_name and msg_namelen logic 2013-11-20 21:52:30 -05:00
link_watch.c net: make all team port device link events urgent 2013-06-13 02:31:41 -07:00
Makefile net: netprio: rename config to be more consistent with cgroup configs 2014-01-03 23:41:42 +01:00
neighbour.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-01-06 17:37:45 -05:00
net_namespace.c userns: Kill nsown_capable it makes the wrong thing easy 2013-08-30 23:44:11 -07:00
net-procfs.c
net-sysfs.c net: netdev_kobject_init: annotate with __init 2014-01-05 20:27:54 -05:00
net-sysfs.h net: netdev_kobject_init: annotate with __init 2014-01-05 20:27:54 -05:00
net-traces.c
netclassid_cgroup.c net: net_cls: move cgroupfs classid handling into core 2014-01-03 23:41:41 +01:00
netevent.c
netpoll.c netpoll: Fix missing TXQ unlock and and OOPS. 2014-01-02 19:50:52 -05:00
netprio_cgroup.c net: more spelling fixes 2013-12-10 21:57:11 -05:00
pktgen.c {pktgen, xfrm} Update IPv4 header total len and checksum after tranformation 2013-12-01 20:33:52 -05:00
request_sock.c
rtnetlink.c netlink: cleanup rntl_af_register 2014-01-01 23:42:19 -05:00
scm.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2013-09-07 14:35:32 -07:00
secure_seq.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-10-23 16:49:34 -04:00
skbuff.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jesse/openvswitch 2014-01-06 19:48:38 -05:00
sock_diag.c sock_diag: fix filter code sent to userspace 2013-06-10 22:23:32 -07:00
sock.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next 2014-01-05 20:18:50 -05:00
stream.c net: add sk_stream_is_writeable() helper 2013-07-24 17:54:48 -07:00
sysctl_net_core.c rps: NUMA flow limit allocations 2013-12-19 19:00:07 -05:00
timestamping.c
user_dma.c
utils.c net: make net_get_random_once irq safe 2013-10-25 19:03:39 -04:00