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

Pavel Machek
2007-02-25T10:42:06Z

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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