From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763817AbXGaOTY (ORCPT ); Tue, 31 Jul 2007 10:19:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758860AbXGaOTJ (ORCPT ); Tue, 31 Jul 2007 10:19:09 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:36410 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759951AbXGaOTH (ORCPT ); Tue, 31 Jul 2007 10:19:07 -0400 Date: Tue, 31 Jul 2007 16:18:57 +0200 From: Ingo Molnar To: Matthew Hawkins Cc: Kenneth Prugh , ck@vds.kolivas.org, Linus Torvalds , Kasper Sandberg , Linux Kernel Mailing List Subject: Re: [ck] Re: SD still better than CFS for 3d ?(was Re: 2.6.23-rc1) Message-ID: <20070731141857.GA22209@elte.hu> References: <20070729170641.GA26220@elte.hu> <930f95dc0707291154j102494d9m58f4cc452c7ff17c@mail.gmail.com> <20070729204716.GB1578@elte.hu> <930f95dc0707291431j4e50214di3c01cd44b5597502@mail.gmail.com> <20070730114649.GB19186@elte.hu> <46AE25F3.7020904@gmail.com> <20070730191029.GA29327@elte.hu> <46AE570B.3050802@gmail.com> <20070731094526.GA16300@elte.hu> 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: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 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 * Matthew Hawkins wrote: > On 7/31/07, Ingo Molnar wrote: > > * Kenneth Prugh wrote: > > > CFS generally seemed a lot smoother as the load increased, while > > > SD broke down to a highly unstable fps count that fluctuated > > > massively around the third loop. Seems like I will stick to CFS > > > for gaming now. > > My experience was quite similar. I noticed after launching the second > loop that the FPS stuck down to 15 for about 20 seconds, then climbed > back up to 48. After that it went rapidly downhill. This is similar > to other benchmarks I've done of SD versus CFS in the past. At a > "normal" load they're fairly similar but SD breaks down under > pressure. ok, thanks for testing it! > The only other thing of interest is that the -ck kernel had the WM > menus appear in about 3 seconds rather than 5-8 under the other two. under what load is that - 10 loops? There's no disk or network IO going on during a WM menu appearance, correct? This could be a time-slicing difference perhaps - if you have CONFIG_HZ=100 could you change it to 1000 (or if you have it at 1000, could you change it to 100) - does it show any sensitivity to that? the other difference could be SCHED_FEAT_START_DEBIT, does that WM menu latency go down if you clear it from sched_features, i.e. to subtract 16 from sched_features: echo 15 > /proc/sys/kernel/sched_features to restore the default, do: echo 31 > /proc/sys/kernel/sched_features (if you have CONFIG_SCHED_DEBUG=y). You might also want to try changing /proc/sys/kernel/sched_granularity_ns. Boundary conditions: make sure that if you change the sched_granularity value you also set /proc/sys/kernel/sched_runtime_limit_ns to 2*sched_granularity and set /proc/sys/kernel/sched_wakeup_granularity_ns to sched_granularity/2. Other interesting bits to experiment with in sched_features would be SCHED_FEAT_FAIR_SLEEPERS (mask '1' in the bitmask) and SCHED_FEAT_SKIP_INITIAL (mask '32' in the bitmask). Ingo