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Date:	Sun, 25 Feb 2007 11:41:54 +0100
From:	Pavel Machek <pavel@....cz>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	bert hubert <bert.hubert@...herlabs.nl>,
	Andi Kleen <andi@...stfloor.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?

Hi!

> > I've done so, with some interesting results. Source on
> > http://ds9a.nl/tmp/recvtimings.c - be careful to adjust the '3000' divider
> > to your CPU frequency if you care about absolute numbers!
> > 
> > These are two groups, each consisting of 10 consecutive nonblocking UDP
> > recvfroms, with 10 packets preloaded. Reported is the number of microseconds
> > per recvfrom call which yielded a packet:
> > 
> > $ ./recvtimings
> > 4.142333
> 
> It can be recvfrom only problem - syscall overhead on my p4 (core duo,
> debian testing) is bout 300 usec - to test I ran 

core duo is _not_ p4 class cpu; rsulets there will be very different.

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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