From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20130507035859.233096969@goodmis.org> Date: Mon, 06 May 2013 23:59:01 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasily Averin , Alexey Kuznetsov , Eric Dumazet , "David S. Miller" Subject: [109/126] cbq: incorrect processing of high limits References: <20130507035712.909872333@goodmis.org> Content-Disposition: inline; filename=0109-cbq-incorrect-processing-of-high-limits.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.6.11.3 stable review patch. If anyone has any objections, please let me know. ------------------ From: Vasily Averin [ Upstream commit f0f6ee1f70c4eaab9d52cf7d255df4bd89f8d1c2 ] currently cbq works incorrectly for limits > 10% real link bandwidth, and practically does not work for limits > 50% real link bandwidth. Below are results of experiments taken on 1 Gbit link In shaper | Actual Result -----------+--------------- 100M | 108 Mbps 200M | 244 Mbps 300M | 412 Mbps 500M | 893 Mbps This happen because of q->now changes incorrectly in cbq_dequeue(): when it is called before real end of packet transmitting, L2T is greater than real time delay, q_now gets an extra boost but never compensate it. To fix this problem we prevent change of q->now until its synchronization with real time. Signed-off-by: Vasily Averin Reviewed-by: Alexey Kuznetsov Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Steven Rostedt --- net/sched/sch_cbq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c index 564b9fc..611d5e9 100644 --- a/net/sched/sch_cbq.c +++ b/net/sched/sch_cbq.c @@ -963,8 +963,11 @@ cbq_dequeue(struct Qdisc *sch) cbq_update(q); if ((incr -= incr2) < 0) incr = 0; + q->now += incr; + } else { + if (now > q->now) + q->now = now; } - q->now += incr; q->now_rt = now; for (;;) { -- 1.7.10.4