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Date: Tue, 06 Jun 2017 13:53:33 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>
Subject: 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 <edumazet@...gle.com>
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