Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?

From: Pavel Machek <[email-masked]>
Date: Sun, 25 Feb 2007 11:41:54 +0100

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

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