Re: [PATCH net-next v2 2/3] udp: avoid a cache miss on dequeue

On Tue, 2017-06-06 at 16:23 +0200, Paolo Abeni wrote:

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.

Acked-by: Eric Dumazet <redacted>