Commit f0f6ee1f authored by Vasily Averin's avatar Vasily Averin Committed by David S. Miller

cbq: incorrect processing of high limits

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: default avatarVasily Averin <vvs@openvz.org>
Reviewed-by: default avatarAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bab6a9ea
......@@ -962,8 +962,11 @@ 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_rt = now;
for (;;) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment