| Message ID | 1306184562.2638.14.camel@edumazet-laptop |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Mon, 23 May 2011 23:02:42 +0200 > While chasing a possible net_sched bug, I found that IP fragments have > litle chance to pass a congestioned SFQ qdisc : > > - Say SFQ qdisc is full because one flow is non responsive. > - ip_fragment() wants to send two fragments belonging to an idle flow. > - sfq_enqueue() queues first packet, but see queue limit reached : > - sfq_enqueue() drops one packet from 'big consumer', and returns > NET_XMIT_CN. > - ip_fragment() cancel remaining fragments. > > This patch restores fairness, making sure we return NET_XMIT_CN only if > we dropped a packet from the same flow. > > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Looks good, applied, thanks Eric. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 7ef87f9..b1d00f8 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -361,7 +361,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) { struct sfq_sched_data *q = qdisc_priv(sch); unsigned int hash; - sfq_index x; + sfq_index x, qlen; struct sfq_slot *slot; int uninitialized_var(ret); @@ -405,8 +405,12 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) if (++sch->q.qlen <= q->limit) return NET_XMIT_SUCCESS; + qlen = slot->qlen; sfq_drop(sch); - return NET_XMIT_CN; + /* Return Congestion Notification only if we dropped a packet + * from this flow. + */ + return (qlen != slot->qlen) ? NET_XMIT_CN : NET_XMIT_SUCCESS; } static struct sk_buff *
While chasing a possible net_sched bug, I found that IP fragments have litle chance to pass a congestioned SFQ qdisc : - Say SFQ qdisc is full because one flow is non responsive. - ip_fragment() wants to send two fragments belonging to an idle flow. - sfq_enqueue() queues first packet, but see queue limit reached : - sfq_enqueue() drops one packet from 'big consumer', and returns NET_XMIT_CN. - ip_fragment() cancel remaining fragments. This patch restores fairness, making sure we return NET_XMIT_CN only if we dropped a packet from the same flow. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Patrick McHardy <kaber@trash.net> CC: Jarek Poplawski <jarkao2@gmail.com> CC: Jamal Hadi Salim <hadi@cyberus.ca> CC: Stephen Hemminger <shemminger@vyatta.com> --- net/sched/sch_sfq.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html