From 0a463c78d25b9464b77311d9dda297550a2d6aa5 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 12 Jun 2017 11:23:42 +0200 Subject: udp: avoid a cache miss on dequeue Since UDP no more uses sk->destructor, we can clear completely the skb head state before enqueuing. Amend and use skb_release_head_state() for that. All head states share a single cacheline, which is not normally used/accesses on dequeue. We can avoid entirely accessing such cacheline implementing and using in the UDP code a specialized skb free helper which ignores the skb head state. This saves a cacheline miss at skb deallocation time. v1 -> v2: replaced secpath_reset() with skb_release_head_state() Signed-off-by: Paolo Abeni Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/udp.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/ipv4') diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index fdcb7437cc15..d8b265f1a33b 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1359,7 +1359,8 @@ void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len) sk_peek_offset_bwd(sk, len); unlock_sock_fast(sk, slow); } - consume_skb(skb); + + consume_stateless_skb(skb); } EXPORT_SYMBOL_GPL(skb_consume_udp); @@ -1739,6 +1740,9 @@ static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) sk_mark_napi_id_once(sk, skb); } + /* clear all pending head states while they are hot in the cache */ + skb_release_head_state(skb); + rc = __udp_enqueue_schedule_skb(sk, skb); if (rc < 0) { int is_udplite = IS_UDPLITE(sk); -- cgit v1.2.3-58-ga151