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Date:	Sun, 25 Feb 2007 11:41:54 +0100
From:	Pavel Machek <>
To:	Evgeniy Polyakov <>
Cc:	bert hubert <>,
	Andi Kleen <>,,
Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?


> > I've done so, with some interesting results. Source on
> > - 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.


(cesky, pictures)
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