From 1ee5fa1e9970a16036e37c7b9d5ce81c778252fc Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 1 Dec 2011 11:06:34 +0000 Subject: sch_red: fix red_change MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le mercredi 30 novembre 2011 à 14:36 -0800, Stephen Hemminger a écrit : > (Almost) nobody uses RED because they can't figure it out. > According to Wikipedia, VJ says that: > "there are not one, but two bugs in classic RED." RED is useful for high throughput routers, I doubt many linux machines act as such devices. I was considering adding Adaptative RED (Sally Floyd, Ramakrishna Gummadi, Scott Shender), August 2001 In this version, maxp is dynamic (from 1% to 50%), and user only have to setup min_th (target average queue size) (max_th and wq (burst in linux RED) are automatically setup) By the way it seems we have a small bug in red_change() if (skb_queue_empty(&sch->q)) red_end_of_idle_period(&q->parms); First, if queue is empty, we should call red_start_of_idle_period(&q->parms); Second, since we dont use anymore sch->q, but q->qdisc, the test is meaningless. Oh well... [PATCH] sch_red: fix red_change() Now RED is classful, we must check q->qdisc->q.qlen, and if queue is empty, we start an idle period, not end it. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_red.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/sched') diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c index 6649463..d617161 100644 --- a/net/sched/sch_red.c +++ b/net/sched/sch_red.c @@ -209,8 +209,8 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt) ctl->Plog, ctl->Scell_log, nla_data(tb[TCA_RED_STAB])); - if (skb_queue_empty(&sch->q)) - red_end_of_idle_period(&q->parms); + if (!q->qdisc->q.qlen) + red_start_of_idle_period(&q->parms); sch_tree_unlock(sch); return 0; -- cgit v1.1