Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754709AbXIQNFi (ORCPT ); Mon, 17 Sep 2007 09:05:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753584AbXIQNFa (ORCPT ); Mon, 17 Sep 2007 09:05:30 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:53428 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752891AbXIQNF3 (ORCPT ); Mon, 17 Sep 2007 09:05:29 -0400 Date: Mon, 17 Sep 2007 15:05:24 +0200 From: Ingo Molnar To: Rob Hussey Cc: linux-kernel@vger.kernel.org, ck@vds.kolivas.org Subject: Re: Scheduler benchmarks - a follow-up Message-ID: <20070917130524.GA10707@elte.hu> References: <6b8cef970709170221s4301e896x2ee123a149c05c3a@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b8cef970709170221s4301e896x2ee123a149c05c3a@mail.gmail.com> 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: 2834 Lines: 70 * Rob Hussey wrote: > http://www.healthcarelinen.com/misc/benchmarks/BOUND_hackbench_benchmark2.png heh - am i the only one impressed by the consistency of the blue line in this graph? :-) [ and the green line looks a bit like a .. staircase? ] i've meanwhile tested hackbench 90 and the performance difference between -ck and -cfs-devel seems to be mostly down to the more precise (but slower) sched_clock() introduced in v2.6.23 and to the startup penalty of freshly created tasks. Putting back the 2.6.22 version and tweaking the startup penalty gives this: [hackbench 90, smaller is better] sched-devel.git sched-devel.git+lowres-sched-clock+dsp --------------- -------------------------------------- 5.555 5.149 5.641 5.149 5.572 5.171 5.583 5.155 5.532 5.111 5.540 5.138 5.617 5.176 5.542 5.119 5.587 5.159 5.553 5.177 -------------------------------------- avg: 5.572 avg: 5.150 (-8.1%) ('lowres-sched-clock' is the patch i sent in the previous mail. 'dsp' is a disable-startup-penalty patch that is in the latest sched-devel.git) i have used your .config to conduct this test. can you reproduce this with the (very-) latest sched-devel git tree: git-pull git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel.git plus with the low-res-sched-clock patch (re-) attached below? Ingo --- arch/i386/kernel/tsc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux/arch/i386/kernel/tsc.c =================================================================== --- linux.orig/arch/i386/kernel/tsc.c +++ linux/arch/i386/kernel/tsc.c @@ -110,9 +110,9 @@ 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 (1 || unlikely(!tsc_enabled && !tsc_unstable)) /* No locking but a rare wrong value is not a big deal: */ - return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); + return jiffies_64 * (1000000000 / HZ); /* read the Time Stamp Counter: */ rdtscll(this_offset); - 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/