Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759554AbXHDGcq (ORCPT ); Sat, 4 Aug 2007 02:32:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752328AbXHDGcg (ORCPT ); Sat, 4 Aug 2007 02:32:36 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:60711 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751688AbXHDGcf (ORCPT ); Sat, 4 Aug 2007 02:32:35 -0400 Date: Sat, 4 Aug 2007 08:32:17 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk Subject: Re: [PATCH 00/23] per device dirty throttling -v8 Message-ID: <20070804063217.GA25069@elte.hu> References: <20070803123712.987126000@chello.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 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: 2252 Lines: 54 * Linus Torvalds wrote: > On Fri, 3 Aug 2007, Peter Zijlstra wrote: > > > > These patches aim to improve balance_dirty_pages() and directly address three > > issues: > > 1) inter device starvation > > 2) stacked device deadlocks > > 3) inter process starvation > > Ok, the patches certainly look pretty enough, and you fixed the only > thing I complained about last time (naming), so as far as I'm > concerned it's now just a matter of whether it *works* or not. I guess > being in -mm will help somewhat, but it would be good to have people > with several disks etc actively test this out. There are positive reports in the never-ending "my system crawls like an XT when copying large files" bugzilla entry: http://bugzilla.kernel.org/show_bug.cgi?id=7372 " vfs_cache_pressure=1 TCQ nr_requests 8 128 not that bad 1 128 snappiest configuration, almost no pauses (or unnoticable ones) " " 1) vfs_cache_pressure at 100, 2.6.21.5+per bdi throttling patch Result is good, not as snappier as I'd want during a large copy but still usable. No process seems stuck for agen, but there seems to be some short (second or subsecond) moment where everything is stuck (like if you run a top d 0.5, the screen is not updated on a regular basis). 2) vfs_cache_pressure at 1, 2.6.21.5+per bdi throttling patch Result is at 2.6.17 level. It is the better combination since 2.6.17. " " 1) I've applied the patches posted by Peter Zijlstra in comment #76 to the 2.6.21-mm2 kernel to check if it removes the problem. My impression is that the problem is still there with those patches, although less visible then with the clean 2.6.21 kernel. " so the whole problem area seems to be a "perfect storm" created by a combination of TCQ, IO scheduling and VM dirty handling weaknesses. Per device dirty throttling is a good step forward and it makes a very visible positive difference. 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/