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authorVasily Averin <vvs@parallels.com>2013-04-01 03:01:32 +0000
committerBen Hutchings <ben@decadent.org.uk>2013-05-13 15:02:34 +0100
commit30a9b2b0fe981f605914df96a8a5d397d64bf7ee (patch)
tree41d9b1580449bb08f1dc983824020e958c42b8de /net/sched
parent67831724738a1d49962631430f3609cb76eeb846 (diff)
cbq: incorrect processing of high limits
[ 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 <vvs@openvz.org> Reviewed-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/sch_cbq.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 599f67ada1ed..b7cddb95397a 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 (;;) {