From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761352AbXHAItg (ORCPT ); Wed, 1 Aug 2007 04:49:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754476AbXHAIt2 (ORCPT ); Wed, 1 Aug 2007 04:49:28 -0400 Received: from mail.gmx.net ([213.165.64.20]:42291 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754447AbXHAIt0 (ORCPT ); Wed, 1 Aug 2007 04:49:26 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+Uqh0puD+URiXaJV9H5qmjsuZ4a2bczgGByMDBp0 Add88tc61ErJvj Subject: Re: CFS review From: Mike Galbraith To: Ingo Molnar Cc: Roman Zippel , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org In-Reply-To: <1185953762.6388.26.camel@Homer.simpson.net> References: <20070711211638.GE18767@one.firstfloor.org> <20070711214649.GK14435@v2.random> <1184302024.6709.11.camel@Homer.simpson.net> <1184389456.6632.13.camel@Homer.simpson.net> <20070801071230.GA16375@elte.hu> <1185953195.6388.21.camel@Homer.simpson.net> <20070801073042.GB21551@elte.hu> <1185953762.6388.26.camel@Homer.simpson.net> Content-Type: text/plain Date: Wed, 01 Aug 2007 10:49:21 +0200 Message-Id: <1185958161.6375.14.camel@Homer.simpson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-08-01 at 09:36 +0200, Mike Galbraith wrote: > On Wed, 2007-08-01 at 09:30 +0200, Ingo Molnar wrote: > > > yeah, the posted numbers look most weird, but there's a complete lack of > > any identification of test environment - so we'll need some more word > > >from Roman. Perhaps this was run on some really old box that does not > > have a high-accuracy sched_clock()? The patch below should simulate that > > scenario on 32-bit x86. > > > > Ingo > > > > Index: linux/arch/i386/kernel/tsc.c > > =================================================================== > > --- linux.orig/arch/i386/kernel/tsc.c > > +++ linux/arch/i386/kernel/tsc.c > > @@ -110,7 +110,7 @@ unsigned long long native_sched_clock(vo > > * very important for it to be as fast as the platform > > * can achive it. ) > > */ > > - if (unlikely(!tsc_enabled && !tsc_unstable)) > > +// if (unlikely(!tsc_enabled && !tsc_unstable)) > > /* No locking but a rare wrong value is not a big deal: */ > > return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); > > > > Ah, thanks. I noticed that clocksource= went away. I'll test with > stats, with and without jiffies resolution. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND 6465 root 20 0 1432 356 296 R 30 0.0 1:02.55 1 chew 6462 root 20 0 1576 216 140 R 23 0.0 0:50.29 1 massive_intr_x 6463 root 20 0 1576 216 140 R 23 0.0 0:50.23 1 massive_intr_x 6464 root 20 0 1576 216 140 R 23 0.0 0:50.28 1 massive_intr_x Well, jiffies resolution clock did upset fairness a bit with a right at jiffies resolution burn time, but not nearly as bad as on Roman's box, and not in favor of the sleepers. With the longer burn time of stock massive_intr.c (8ms burn, 1ms sleep), lower resolution clock didn't upset it. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND 6511 root 20 0 1572 220 140 R 25 0.0 1:00.11 1 massive_intr 6512 root 20 0 1572 220 140 R 25 0.0 1:00.14 1 massive_intr 6514 root 20 0 1432 356 296 R 25 0.0 1:00.31 1 chew 6513 root 20 0 1572 220 140 R 24 0.0 1:00.14 1 massive_intr -Mike