Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964784AbXBYKmG (ORCPT ); Sun, 25 Feb 2007 05:42:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964783AbXBYKmF (ORCPT ); Sun, 25 Feb 2007 05:42:05 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:40248 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964778AbXBYKmE (ORCPT ); Sun, 25 Feb 2007 05:42:04 -0500 Date: Sun, 25 Feb 2007 11:41:54 +0100 From: Pavel Machek To: Evgeniy Polyakov Cc: bert hubert , Andi Kleen , 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? Message-ID: <20070225104154.GA2045@elf.ucw.cz> References: <20070219231447.GA4400@outpost.ds9a.nl> <20070220162714.GA3245@outpost.ds9a.nl> <20070220164124.GA24930@2ka.mipt.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070220164124.GA24930@2ka.mipt.ru> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1047 Lines: 28 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/