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authorVasily Averin2013-03-31 22:01:32 -0500
committerGreg Kroah-Hartman2013-05-01 11:46:16 -0500
commitd0a353c0fe80641a90e87a6f97305b2206ab8f34 (patch)
tree55508fcbe6175221328db2405c14d8730be7af6e /net
parent7c824b03b007b5fd594a8dd91858325c2daa6f4b (diff)
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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.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 0e19948470b..ced81a1583e 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -962,8 +962,11 @@ cbq_dequeue(struct Qdisc *sch)
962 cbq_update(q); 962 cbq_update(q);
963 if ((incr -= incr2) < 0) 963 if ((incr -= incr2) < 0)
964 incr = 0; 964 incr = 0;
965 q->now += incr;
966 } else {
967 if (now > q->now)
968 q->now = now;
965 } 969 }
966 q->now += incr;
967 q->now_rt = now; 970 q->now_rt = now;
968 971
969 for (;;) { 972 for (;;) {