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

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Date:   Mon, 21 Nov 2016 14:01:20 -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 22:36 +0100, Paolo Abeni wrote:

> Nice catch, thank you Eric!
> 
> This gives up to 8% speed-up in my performance test (wire speed udp flood
> with small packets)
> 
> 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.