Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752909AbXFNU5o (ORCPT ); Thu, 14 Jun 2007 16:57:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751629AbXFNU5e (ORCPT ); Thu, 14 Jun 2007 16:57:34 -0400 Received: from comtv.ru ([217.10.32.17]:58141 "EHLO comtv.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751549AbXFNU5d (ORCPT ); Thu, 14 Jun 2007 16:57:33 -0400 X-UCL: actv Date: Fri, 15 Jun 2007 00:56:27 +0400 (MSD) From: malc X-X-Sender: malc@linmac.oyster.ru To: Ingo Molnar cc: linux-kernel@vger.kernel.org Subject: Re: [patch] sched: accurate user accounting In-Reply-To: <20070614204253.GA14076@elte.hu> Message-ID: References: <200703251159.03616.kernel@kolivas.org> <200703260901.54943.kernel@kolivas.org> <200703260957.34798.kernel@kolivas.org> <20070328113743.GA5615@elte.hu> <20070614204253.GA14076@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2519 Lines: 60 On Thu, 14 Jun 2007, Ingo Molnar wrote: > > * Vassili Karpov wrote: > >> Hello Ingo and others, >> >> After reading http://lwn.net/Articles/236485/ and noticing few >> refernces to accounting i decided to give CFS a try. With >> sched-cfs-v2.6.21.4-16 i get pretty weird results, it seems like >> scheduler is dead set on trying to move the processes to different >> CPUs/cores all the time. And with hog (manually tweaking the amount >> iterations) i get fairly strange resuls, first of all the process is >> split between two cores, secondly while integral load provided by the >> kernel looks correct, it's off by good 20 percent on each idividial >> core. >> >> (http://www.boblycat.org/~malc/apc/hog-cfs-v16.png) >> >> Thought this information might be of some interest. > > hm - what does 'hog' do, can i download hog.c from somewhere? http://www.boblycat.org/~malc/apc/hog.c and also a in Documentation/cpu-load.txt. > > the alternating balancing might be due to an uneven number of tasks > perhaps? If you have 3 tasks on 2 cores then there's no other solution > to achieve even performance of each task but to rotate them amongst the > cores. One task, one thread. I have also tried to watch fairly demanding video (Elephants Dream in 1920x1080/MPEG4) with mplayer, and CFS moves the only task between cores almost every second. >> P.S. How come the /proc/stat information is much closer to reality >> now? Something like what Con Kolivas suggested was added to >> sched.c? > > well, precise/finegrained accounting patches have been available for > years, the thing with CFS is that there we get them 'for free', because > CFS needs those metrics for its own logic. That's why this information > is much closer to reality now. But note: right now what is affected by > the changes in the CFS patches is /proc/PID/stat (i.e. the per-task > information that 'top' and 'ps' displays, _not_ /proc/stat) - but more > accurate /proc/stat could certainly come later on too. Aha. I see, it's just that integral load for hog is vastly improved compared to vanilla 2.6.21 (then again some other tests are off by a few percent (at least), though they were fine with Con's patch (which was announced at the beginning of this thread)) -- vale - 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/