From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756790Ab0CJPzP (ORCPT ); Wed, 10 Mar 2010 10:55:15 -0500 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:41483 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756766Ab0CJPzO (ORCPT ); Wed, 10 Mar 2010 10:55:14 -0500 Date: Wed, 10 Mar 2010 16:55:11 +0100 From: Jens Axboe To: Frederic Weisbecker Cc: Ingo Molnar , LKML , Peter Zijlstra , Arnaldo Carvalho de Melo , Steven Rostedt , Paul Mackerras , Hitoshi Mitake , Li Zefan , Lai Jiangshan , Masami Hiramatsu Subject: Re: [PATCH 1/3] lockdep: Move lock events under lockdep recursion protection Message-ID: <20100310155511.GZ5768@kernel.dk> References: <1267599302-2886-1-git-send-regression-fweisbec@gmail.com> <1267599302-2886-2-git-send-regression-fweisbec@gmail.com> <20100309083410.GD5768@kernel.dk> <20100309234518.GE5058@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100309234518.GE5058@nowhere> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 10 2010, Frederic Weisbecker wrote: > On Tue, Mar 09, 2010 at 09:34:10AM +0100, Jens Axboe wrote: > > I went to try this on 2.6.34-rc1 to see how much it would improve things > > here. With 2.6.34-rc1, a > > > > $ time sudo perf lock record ls /dev/shm > > > > essentially hangs the box, it ends up crashing hard (not just live > > locked like before). With the patch in place, it does eventually finish: > > > > real 0m21.301s > > user 0m0.030s > > sys 0m21.040s > > > > The directory is empty. > > > Hehe :-) > > That said you are probably missing a part of the puzzle. > This patch avoids the scary recursions we had. But there > is another separate patch that fixes the buffers multiplexing > dependency we had. Buffering is now done per cpu. > > You need this patch: > > commit b67577dfb45580c498bfdb1bc76c00c3b2ad6310 > Author: Frederic Weisbecker > Date: Wed Feb 3 09:09:33 2010 +0100 > > perf lock: Drop the buffers multiplexing dependency > > But this is not in -rc1, you need to checkout tip/perf/core > > Well, the best would be you actually pull this on top of -rc1: > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git > perf/core > > so that you get the buffers multiplexing dependency that is in -tip, > and you also get the recursions fixes, not yet in -tip (but should make > it soon). > > I bet you still won't have magic results after that, but still it should > be better. OK, I will give it a spin and see what happens. I had seen the de-multiplexing patch, but just assumed it was in -rc1 already. > We still have further projects in mind to improve the scalability, > like the events injection thing (that avoids the string copy) > > Again, you are my eyes on this, I'm still blind with my poor dual > laptop or my atom testbox. > > Thanks for your testing. Not a problem, thank you for trying to get some nicer lock profiling in the kernel :-) -- Jens Axboe