Re: bad networking related lag in v2.6.22-rc2

From: Herbert Xu
Date: Wed May 23 2007 - 07:27:33 EST


On Wed, May 23, 2007 at 12:56:04PM +0200, Patrick McHardy wrote:
>
> Looking at the recent changes to __qdisc_run, this indeed seems
> to be the case, when the qdisc is throttled and has packets queued
> we return a value != 0, causing __qdisc_run to loop until all
> packets have been sent, which may be a long time.

Good catch! I was obviously half awake at the time :)

We could also fix it this way:

[NET_SCHED]: Fix qdisc_restart return value when dequeue is empty

My previous patch that changed the return value of qdisc_restart
incorrectly made the case where dequeue returns empty continue
processing packets.

This patch is based on diagnosis and fix by Patrick McHardy.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Thanks,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index f28bb2d..cbefe22 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -169,8 +169,8 @@ requeue:
else
q->ops->requeue(skb, q);
netif_schedule(dev);
- return 0;
}
+ return 0;

out:
BUG_ON((int) q->q.qlen < 0);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/