netdev - Re: [PATCH net-next] net: ipv6: Add early demux handler for UDP unicast

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Message-ID: <1489000921.28631.18.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Wed, 08 Mar 2017 11:22:01 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Cc:     netdev@...r.kernel.org, netdev-owner@...r.kernel.org
Subject: Re: [PATCH net-next] net: ipv6: Add early demux handler for UDP
 unicast

On Wed, 2017-03-08 at 12:11 -0700, Subash Abhinov Kasiviswanathan wrote:
> On 2017-03-08 11:40, Eric Dumazet wrote:
> > Well, this 'optimization' actually hurts when UDP sockets are not
> > connected, since this adds an extra cache line miss per incoming 
> > packet.
> > 
> > (DNS servers for example)
> 
> Hi Eric
> 
> Thanks for your comments. Would it be preferable to disable early demux 
> for the
> servers with large unconnected workloads in that case?

Well, many servers handle both TCP and UDP.

For TCP, there is no question about early demux, this is definitely a
win.

We probably should have one sysctl to enable TCP early demux, one for
UDP early demux.