From 520ac30f45519b0a82dd92117c181d1d6144677b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 21 Jun 2016 23:16:49 -0700 Subject: net_sched: drop packets after root qdisc lock is released Qdisc performance suffers when packets are dropped at enqueue() time because drops (kfree_skb()) are done while qdisc lock is held, delaying a dequeue() draining the queue. Nominal throughput can be reduced by 50 % when this happens, at a time we would like the dequeue() to proceed as fast as possible. Even FQ is vulnerable to this problem, while one of FQ goals was to provide some flow isolation. This patch adds a 'struct sk_buff **to_free' parameter to all qdisc->enqueue(), and in qdisc_drop() helper. I measured a performance increase of up to 12 %, but this patch is a prereq so that future batches in enqueue() can fly. Signed-off-by: Eric Dumazet Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- net/sched/sch_drr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'net/sched/sch_drr.c') diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index 22609e4e845f..8af5c59eef84 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -350,7 +350,8 @@ static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch, return NULL; } -static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch) +static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch, + struct sk_buff **to_free) { struct drr_sched *q = qdisc_priv(sch); struct drr_class *cl; @@ -360,11 +361,11 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch) if (cl == NULL) { if (err & __NET_XMIT_BYPASS) qdisc_qstats_drop(sch); - kfree_skb(skb); + __qdisc_drop(skb, to_free); return err; } - err = qdisc_enqueue(skb, cl->qdisc); + err = qdisc_enqueue(skb, cl->qdisc, to_free); if (unlikely(err != NET_XMIT_SUCCESS)) { if (net_xmit_drop_count(err)) { cl->qstats.drops++; -- cgit v1.2.3