netdev - Re: [PATCH net-next] udp: avoid one cache line miss in recvmsg()

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Message-ID: <1479765954.8455.424.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 21 Nov 2016 14:05:54 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] udp: avoid one cache line miss in recvmsg()

On Mon, 2016-11-21 at 14:01 -0800, Eric Dumazet wrote:
> Tested-by: Paolo Abeni <pabeni@...hat.com>
> 
> Thanks Paolo
> 
> Note that udp6_recvmsg() hits the 3rd cache line of skb to access
> skb->protocol :
> 
> is_udp4 = (skb->protocol == htons(ETH_P_IP));
> 
> We might some trick to avoid this cache line miss.

Argh, ignore this.

net-next kernel has this field at offset 0xc0, so all is good (since
this 4th cache line contains other needed fields)