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| author | Vasily Averin <vvs@parallels.com> | 2013-04-01 03:01:32 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-05-01 08:56:36 -0700 |
| commit | f7b8a0f5795aca696f78042db1b8c4b3d07e04c5 (patch) | |
| tree | 5a4725d65fbcebafbb6ab5bb9056892bd8a20446 /net | |
| parent | 9758b79c56ae6dc93f660928a0d389ba45e530ed (diff) | |
| download | lwn-f7b8a0f5795aca696f78042db1b8c4b3d07e04c5.tar.gz lwn-f7b8a0f5795aca696f78042db1b8c4b3d07e04c5.zip | |
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/sch_cbq.c | 5 |
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 (;;) { |