From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752070Ab0HTNTm (ORCPT ); Fri, 20 Aug 2010 09:19:42 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:41224 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751724Ab0HTNTk (ORCPT ); Fri, 20 Aug 2010 09:19:40 -0400 Date: Fri, 20 Aug 2010 15:19:20 +0200 From: Ingo Molnar To: Tim Chen Cc: Linus Torvalds , Thomas Gleixner , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , peterz@infradead.org, Andrew Morton , linux-kernel@vger.kernel.org, Andi Kleen , Tony Luck Subject: Re: [PATCH 1/1] mutex: prevent optimistic spinning from spinning longer than neccessary (Repost) Message-ID: <20100820131920.GC3321@elte.hu> References: <1282168827.9542.72.camel@schen9-DESK> <20100819110511.GA16264@elte.hu> <1877.10.21.68.23.1282256686.squirrel@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1877.10.21.68.23.1282256686.squirrel@linux.intel.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 1.0 X-ELTE-SpamLevel: s X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=1.0 required=5.9 tests=BAYES_50 autolearn=no SpamAssassin version=3.2.5 1.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.4540] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Tim Chen wrote: > > Ingo wrote: > > > > These are some rather impressive speedups! > > > > Have you tried to see what performance effects this change has on > smaller > > boxes? Just to see what flip side (if any) this change has. > > > > I've done similar experiments with 2.6.35 kernel on smaller boxes. One is > on a dual-socket Westmere box (12 cores total, with HT). Another > experiment is on an old dual-socket Core 2 box (4 cores total, no HT) > > On the 12-core Westmere box, I see a 250% increase for Ingo's mutex-test > program with my mutex patch but no significant difference in aim7's > fserver workload. > > On the 4-core Core 2 box, I see the difference with the patch for both > mutex-test and aim7 fserver are negligible. Great! > So far, it seems like the patch has not caused regression on smaller > systems. We'll put it through more workloads to check. Thanks! The performance results you've posted so far IMO more than justifies its inclusion. Ingo