From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] ipv4: Add sysctl knob to control early socket demux
Date: Fri, 22 Jun 2012 23:00:22 -0700 (PDT)
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 23 Jun 2012 07:45:26 +0200

> On Fri, 2012-06-22 at 17:15 -0700, David Miller wrote:
> 
>> Furthermore, we can reduce to overhead by making a special inet
>> established hash demux that doesn't check for time-wait sockets,
>> reducing the number of probes to 1 from 2.
> 
> The timewait hash chain is on the same cache line than established one.
> And on a router, both chains are empty with a 99.999 % probability.

I understand this.

Probably a lot of the overhead has to do with the function calls
and, as I mentioned, the transport layer probing and validation.