From mboxrd@z Thu Jan 1 00:00:00 1970 From: bert hubert Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz? Date: Tue, 20 Feb 2007 23:17:20 +0100 Message-ID: <20070220221719.GA16263@outpost.ds9a.nl> References: <20070219231447.GA4400@outpost.ds9a.nl> <20070220162714.GA3245@outpost.ds9a.nl> <20070220164124.GA24930@2ka.mipt.ru> <20070220184242.GA30077@filer.fsl.cs.sunysb.edu> <20070220184859.GA1949@2ka.mipt.ru> <20070220193319.GA8800@outpost.ds9a.nl> <45DB6FD8.4050106@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Evgeniy Polyakov , Josef Sipek , Andi Kleen , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Rick Jones Return-path: Received: from outpost.ds9a.nl ([213.244.168.210]:39938 "EHLO outpost.ds9a.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030193AbXBTWRV (ORCPT ); Tue, 20 Feb 2007 17:17:21 -0500 Content-Disposition: inline In-Reply-To: <45DB6FD8.4050106@hp.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Feb 20, 2007 at 02:02:00PM -0800, Rick Jones wrote: > The slope appears to be flattening-out the farther out to the right it > goes. Perhaps that is the length of time it takes to take all the > requisite cache misses. The rate of flattening out appears to correlate with the number of processes running, even though the system is otherwise >99.5% idle during my measurements. With only 'gdm' running, things flatten out slowly, iow, it takes longer delays to see recvfrom slow down. With only 1 process running (init=bash), the graph is nearly flat. >>From this, it is probable that even an idle GNOME desktop (Ubunty Edgy Eft) is under fierce cache pressure, enough to blow away my meagre 1MB in a matter of milliseconds. I'm trying to figure out which processes have the most impact, I had already killed anything non-essential. But that still leaves 140 pids. Bert -- http://www.PowerDNS.com Open source, database driven DNS Software http://netherlabs.nl Open and Closed source services