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

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Date:   Tue, 06 Jun 2017 13:58:35 -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 3/3] udp: try to avoid 2 cache miss on
 dequeue

On Tue, 2017-06-06 at 16:23 +0200, Paolo Abeni wrote:
> when udp_recvmsg() is executed, on x86_64 and other archs, most skb
> fields are on cold cachelines.
> If the skb are linear and the kernel don't need to compute the udp
> csum, only a handful of skb fields are required by udp_recvmsg().
> Since we already use skb->dev_scratch to cache hot data, and
> there are 32 bits unused on 64 bit archs, use such field to cache
> as much data as we can, and try to prefetch on dequeue the relevant
> fields that are left out.

Acked-by: Eric Dumazet <edumazet@...gle.com>