From d47a0ac7b66883987275598d6039f902f4410ca9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 1 Jan 2012 18:33:31 +0000 Subject: [PATCH] sch_sfq: dont put new flow at the end of flows SFQ enqueue algo puts a new flow _behind_ all pre-existing flows in the circular list. In fact this is probably an old SFQ implementation bug. 100 Mbits = ~8333 full frames per second, or ~8 frames per ms. With 50 flows, it means your "new flow" will have to wait 50 packets being sent before its own packet. Thats the ~6ms. We certainly can change SFQ to give a priority advantage to new flows, so that next dequeued packet is taken from a new flow, not an old one. Reported-by: Dave Taht Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_sfq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index d329a8a72357..e9d5c911576d 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -366,11 +366,11 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) if (slot->qlen == 1) { /* The flow is new */ if (q->tail == NULL) { /* It is the first flow */ slot->next = x; + q->tail = slot; } else { slot->next = q->tail->next; q->tail->next = x; } - q->tail = slot; slot->allot = q->scaled_quantum; } if (++sch->q.qlen <= q->limit)