path: root/net/sched/sch_sfb.c
diff options
authorEric Dumazet <edumazet@google.com>2016-06-21 23:16:49 -0700
committerDavid S. Miller <davem@davemloft.net>2016-06-25 12:19:35 -0400
commit520ac30f45519b0a82dd92117c181d1d6144677b (patch)
treea3189ae1ab3b5be6213716e42ddaec082578e774 /net/sched/sch_sfb.c
parentMerge branch 'liquidio-next' (diff)
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 <edumazet@google.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_sfb.c')
1 files changed, 4 insertions, 3 deletions
diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
index c69611640fa5..add3cc7d37ec 100644
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -275,7 +275,8 @@ static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl,
return false;
-static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
struct sfb_sched_data *q = qdisc_priv(sch);
@@ -397,7 +398,7 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
- ret = qdisc_enqueue(skb, child);
+ ret = qdisc_enqueue(skb, child, to_free);
if (likely(ret == NET_XMIT_SUCCESS)) {
increment_qlen(skb, q);
@@ -408,7 +409,7 @@ enqueue:
return ret;
- qdisc_drop(skb, sch);
+ qdisc_drop(skb, sch, to_free);
return NET_XMIT_CN;
if (ret & __NET_XMIT_BYPASS)