Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763412AbZAOSGx (ORCPT ); Thu, 15 Jan 2009 13:06:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757075AbZAOSGk (ORCPT ); Thu, 15 Jan 2009 13:06:40 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:55785 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756283AbZAOSGi (ORCPT ); Thu, 15 Jan 2009 13:06:38 -0500 Date: Thu, 15 Jan 2009 19:06:19 +0100 From: Ingo Molnar To: Matthew Wilcox Cc: Linus Torvalds , Peter Zijlstra , "Paul E. McKenney" , Gregory Haskins , Andi Kleen , Chris Mason , Andrew Morton , Linux Kernel Mailing List , linux-fsdevel , linux-btrfs , Thomas Gleixner , Nick Piggin , Peter Morreale , Sven Dietrich , Dmitry Adamushko , Johannes Weiner Subject: Re: [GIT PULL] adaptive spinning mutexes Message-ID: <20090115180619.GK22472@elte.hu> References: <1231863710.7141.3.camel@twins> <1231864854.7141.8.camel@twins> <1231867314.7141.16.camel@twins> <1231952436.14825.28.camel@laptop> <20090114183319.GA18630@elte.hu> <20090114184746.GA21334@elte.hu> <20090114192811.GA19691@elte.hu> <20090115174440.GF29283@parisc-linux.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090115174440.GF29283@parisc-linux.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.3 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1577 Lines: 37 * Matthew Wilcox wrote: > On Wed, Jan 14, 2009 at 08:28:11PM +0100, Ingo Molnar wrote: > > [v2.6.14] [v2.6.29] > > > > Semaphores | Mutexes > > ---------------------------------------------- > > | no-spin spin > > | > > [tmpfs] ops/sec: 50713 | 291038 392865 (+34.9%) > > [ext3] ops/sec: 45214 | 283291 435674 (+53.7%) > > > > A 10x macro-performance improvement on ext3, compared to 2.6.14 :-) > > > > While lots of other details got changed meanwhile, i'm sure most of > > the performance win on this particular VFS workload comes from > > mutexes. > > I asked a couple of our benchmarking teams to try -v9. Neither the OLTP > benchmark, nor the kernel-perf test suite found any significant > performance change. I suspect mutex contention isn't a significant > problem for most workloads. basically only VFS is mutex-bound really, and few of the 'benchmarks' tend to be VFS intense. Maybe things like mail-server benchmarks would do that. Also, -v9 is like two days old code ;-) Old and crufty. The real performance uptick was not even in -v10 but in -v11 (the one we submitted in this thread). 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/