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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 18 Apr 2017 17:09:04 +0900
From:   Simon Horman <simon.horman@...ronome.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>,
        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, Mar 08, 2017 at 11:22:01AM -0800, Eric Dumazet wrote:
> 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.

If early demux is a clear win for TCP then I wonder if it is
unnecessary and by some leap also undesirable to have a configuration
knob for that case.