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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_hhf.c
parent36195d869e4b1dbf81bafa3a31bb095a3c013bdd (diff)
downloadlinux-stericsson-520ac30f45519b0a82dd92117c181d1d6144677b.tar.gz
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_hhf.c')
-rw-r--r--net/sched/sch_hhf.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/net/sched/sch_hhf.c b/net/sched/sch_hhf.c
index c44593b8e65a..e3d0458af17b 100644
--- a/net/sched/sch_hhf.c
+++ b/net/sched/sch_hhf.c
@@ -345,7 +345,7 @@ static void bucket_add(struct wdrr_bucket *bucket, struct sk_buff *skb)
skb->next = NULL;
}
-static unsigned int hhf_drop(struct Qdisc *sch)
+static unsigned int hhf_drop(struct Qdisc *sch, struct sk_buff **to_free)
{
struct hhf_sched_data *q = qdisc_priv(sch);
struct wdrr_bucket *bucket;
@@ -359,16 +359,16 @@ static unsigned int hhf_drop(struct Qdisc *sch)
struct sk_buff *skb = dequeue_head(bucket);
sch->q.qlen--;
- qdisc_qstats_drop(sch);
qdisc_qstats_backlog_dec(sch, skb);
- kfree_skb(skb);
+ qdisc_drop(skb, sch, to_free);
}
/* Return id of the bucket from which the packet was dropped. */
return bucket - q->buckets;
}
-static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
{
struct hhf_sched_data *q = qdisc_priv(sch);
enum wdrr_bucket_idx idx;
@@ -406,7 +406,7 @@ static int hhf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
/* Return Congestion Notification only if we dropped a packet from this
* bucket.
*/
- if (hhf_drop(sch) == idx)
+ if (hhf_drop(sch, to_free) == idx)
return NET_XMIT_CN;
/* As we dropped a packet, better let upper stack know this. */