From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932958Ab3EGNlR (ORCPT ); Tue, 7 May 2013 09:41:17 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42258 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932574Ab3EGNlJ (ORCPT ); Tue, 7 May 2013 09:41:09 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Vasily Averin , "David S. Miller" , Luis Henriques Subject: [PATCH 042/118] cbq: incorrect processing of high limits Date: Tue, 7 May 2013 14:38:08 +0100 Message-Id: <1367933964-1564-43-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1367933964-1564-1-git-send-email-luis.henriques@canonical.com> References: <1367933964-1564-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.12 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Vasily Averin commit f0f6ee1f70c4eaab9d52cf7d255df4bd89f8d1c2 upstream. 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: Luis Henriques --- 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 (;;) { -- 1.8.1.2