Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932081AbWEHLiW (ORCPT ); Mon, 8 May 2006 07:38:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932082AbWEHLiW (ORCPT ); Mon, 8 May 2006 07:38:22 -0400 Received: from fw5.argo.co.il ([194.90.79.130]:40719 "EHLO argo2k.argo.co.il") by vger.kernel.org with ESMTP id S932081AbWEHLiW (ORCPT ); Mon, 8 May 2006 07:38:22 -0400 Message-ID: <445F2DAA.30301@argo.co.il> Date: Mon, 08 May 2006 14:38:18 +0300 From: Avi Kivity User-Agent: Thunderbird 1.5.0.2 (X11/20060501) MIME-Version: 1.0 To: rmk+lkml@arm.linux.org.uk CC: Arjan van de Ven , Erik Mouw , Andrew Morton , Jason Schoonover , linux-kernel@vger.kernel.org Subject: Re: High load average on disk I/O on 2.6.17-rc3 References: <200605051010.19725.jasons@pioneer-pra.com> <20060507095039.089ad37c.akpm@osdl.org> <20060508111345.GA1875@harddisk-recovery.com> <1147087356.2888.9.camel@laptopd505.fenrus.org> <20060508112831.GA14206@flint.arm.linux.org.uk> In-Reply-To: <20060508112831.GA14206@flint.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 08 May 2006 11:38:19.0909 (UTC) FILETIME=[E7AA3B50:01C67293] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1216 Lines: 30 Russell King wrote: > Why do you think that? exim uses the load average to work out whether > it's a good idea to spawn more copies of itself, and increase the load > on the machine. > > Unfortunately though, under 2.6 kernels, the load average seems to be > a meaningless indication of how busy the system is from that point of > view. > > Having a single CPU machine with a load average of 150 and still feel > very interactive at the shell is extremely counter-intuitive. > It's even worse: load average used to mean the number of runnable processes + number of processes waiting on disk or NFS I/O to complete, a fairly bogus measure as you have noted, but with the aio interfaces one can issue enormous amounts of I/O without it being counted in the load average. To make such decisions real, one needs separate counters for cpu load and for disk load on the devices one is actually using. -- error compiling committee.c: too many arguments to function - 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/