netdev - Re: UDP regression with packets rates

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Message-ID: <4AAF263E.9010405@gmail.com>
Date:	Tue, 15 Sep 2009 07:29:34 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Christoph Lameter <cl@...ux-foundation.org>
CC:	netdev@...r.kernel.org
Subject: Re: UDP regression with packets rates < 10k per sec

Christoph Lameter a écrit :
> Where are we on this? Definitely a regression?

??

I tried to reproduce your numbers and failed on my machines.

2.6.31 is actually faster than 2.6.22 on the bench you provided.

Must be specific to the hardware I guess ?

As text size presumably is bigger in 2.6.31, fetching code
in cpu caches to handle 10 packets per second is what we call
a cold path anyway.

If you want to make it a fast path, you want to make sure code its
always hot in cpu caches, and find a way to inject packets into
the kernel to make sure cpu keep the path hot.

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