From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
To: bert hubert <bert.hubert@netherlabs.nl>
Cc: Andi Kleen <andi@firstfloor.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?
Date: Tue, 20 Feb 2007 19:41:25 +0300 [thread overview]
Message-ID: <20070220164124.GA24930@2ka.mipt.ru> (raw)
In-Reply-To: <20070220162714.GA3245@outpost.ds9a.nl>
On Tue, Feb 20, 2007 at 05:27:14PM +0100, bert hubert (bert.hubert@netherlabs.nl) wrote:
> 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
read('dev/zero', &data, 0)
in a loop.
Could you try to hack recvfrom() for your socket to always copy some
empty buffer and check the results without waiting for packet?
If you are not hurry I can test it myself tomorrow.
--
Evgeniy Polyakov
next prev parent reply other threads:[~2007-02-20 16:41 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-19 23:14 nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz? bert hubert
2007-02-19 23:56 ` Stephen Hemminger
2007-02-20 8:04 ` bert hubert
2007-02-20 10:50 ` Andi Kleen
2007-02-20 16:27 ` all syscalls initially taking 4usec on a P4? " bert hubert
2007-02-20 16:41 ` Evgeniy Polyakov [this message]
2007-02-20 17:02 ` bert hubert
2007-02-20 17:11 ` Evgeniy Polyakov
2007-02-20 17:18 ` Evgeniy Polyakov
2007-02-21 11:06 ` Evgeniy Polyakov
2007-02-21 11:34 ` Andi Kleen
2007-02-20 18:42 ` Josef Sipek
2007-02-20 18:48 ` Evgeniy Polyakov
2007-02-20 19:33 ` bert hubert
2007-02-20 19:40 ` Benjamin LaHaise
2007-02-20 20:45 ` bert hubert
2007-02-20 21:02 ` Stephen Hemminger
2007-02-20 22:02 ` Rick Jones
2007-02-20 22:17 ` bert hubert
2007-02-20 22:22 ` Arjan van de Ven
2007-02-21 16:25 ` Chuck Ebbert
2007-02-20 22:46 ` Ian McDonald
2007-02-25 10:41 ` Pavel Machek
2007-02-25 17:06 ` Evgeniy Polyakov
2007-02-20 16:57 ` Eric Dumazet
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