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Message-ID: <48B57BD3.5050206@hp.com>
Date: Wed, 27 Aug 2008 09:07:47 -0700
From: Rick Jones <rick.jones2@...com>
To: Andi Kleen <andi@...stfloor.org>
CC: Evgeniy Polyakov <johnpol@....mipt.ru>,
Eric Dumazet <dada1@...mosbay.com>,
Denys Fedoryshchenko <denys@...p.net.lb>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: loaded router, excessive getnstimeofday in oprofile
Andi Kleen wrote:
> Evgeniy Polyakov <johnpol@....mipt.ru> writes:
>
>>Yup, this innocent toys can end up with this such behaviour on modern
>>highly loaded machines.
>
>
> I and also other people had some patches to move the time stamp
> measuring into the socket. This way the time stamping didn't need to
> be enabled on all packets, only on those that actually end up at a
> socket that requires the time stamp.
>
> Unfortunately DaveM didn't like it because some bank wanted
> different semantics, see the discussion in
> http://thread.gmane.org/gmane.linux.network/91679
>
> Perhaps you can find out which bank it was and send them a bill for
> your CPU time ;-)
Those banks really want to crank down on latency - to the point they
start disabling interrupt coalescing. I bet they'd toss anything out
they could to shave another microsecond.
rick jones
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