Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756610AbZANT2o (ORCPT ); Wed, 14 Jan 2009 14:28:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753899AbZANT2c (ORCPT ); Wed, 14 Jan 2009 14:28:32 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:36131 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753226AbZANT2b (ORCPT ); Wed, 14 Jan 2009 14:28:31 -0500 Date: Wed, 14 Jan 2009 20:28:11 +0100 From: Ingo Molnar To: Linus Torvalds , Peter Zijlstra Cc: "Paul E. McKenney" , Gregory Haskins , Matthew Wilcox , 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: <20090114192811.GA19691@elte.hu> References: <1231774622.4371.96.camel@laptop> <1231859742.442.128.camel@twins> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090114184746.GA21334@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) 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=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1636 Lines: 40 * Ingo Molnar wrote: > Latest performance figures, on a 2-socket 16-way Nehalem test-system, > running the code above, measured via "test-mutex V 128 10" VFS > creat+unlink scalability test on tmpfs and ext3: > > no-spin spin > > [tmpfs] avg ops/sec: 291038 392865 (+34.9%) > [ext3] avg ops/sec: 283291 435674 (+53.7%) Btw., for historic kicks i just went back to v2.6.15-2019-gf17578d - the last pre-mutexes semaphore based kernel, using the same .config. I tracked down two bugs in it to make it boot on a Nehalem, so we can now compare the above numbers against historic semaphore performance: [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. So i think the long mutex migration pain was definitely worth it. 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/