Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754835AbXI0GzV (ORCPT ); Thu, 27 Sep 2007 02:55:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752915AbXI0GzJ (ORCPT ); Thu, 27 Sep 2007 02:55:09 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:56617 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752644AbXI0GzI (ORCPT ); Thu, 27 Sep 2007 02:55:08 -0400 Date: Thu, 27 Sep 2007 08:54:47 +0200 From: Ingo Molnar To: Andr? Goddard Rosa Cc: Peter Zijlstra , Mike Galbraith , linux-kernel@vger.kernel.org Subject: Re: sched-devel feedback Message-ID: <20070927065447.GA28697@elte.hu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7-deb -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1869 Lines: 47 * Andr? Goddard Rosa wrote: > Hi, Ingo , Mike and Peter! > > Just passing around to say that 2.6.23-rc8-sched-dev is the best > scheduler ever to me. It's great for 3D games. cool! :-) > http://www.openarena.ws/?files is really great with this > scheduler. I played a whole match without no slowdown, smooth playing > all the time. I had never played it before like this, it made a huge > difference to me. Even older CFS releases and -ck did not made it > sooooo smooth. It was really smooth _all_ the time. i'm wondering, in previous schedulers, under what situations did you notice smoothness problems? Was the scenario in any way deterministic, or just random delays that are hard to describe? Just in case you have smoothness problems in the future, a good way of measuring it objectively is to enable CONFIG_SCHED_DEBUG=y and CONFIG_SCHEDSTATS=y and to monitor the se.wait_max field in the /proc/PID/tasks/*/sched file[s]. Every time there's some ruckle or other smoothness problem, that field's value should increase. (a few milliseconds up to a few dozen milliseconds is fine normally - anything above 100 msecs is probably less fine.) By looking at that latency field you can compare two kernels. (And by echoing 0 to the sched file you can clear these stats.) So by saying "under .23-rc8 se.wait_max was 50 msecs while in .24-rc1 it increased to 250 msecs" everyone can effectively complain to us about smoothness problems :-) > The scheduler team did a really good work on this! > > Thank you so much for this great work, you are welcome! Ingo - 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/