From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756488AbZFWK4z (ORCPT ); Tue, 23 Jun 2009 06:56:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752911AbZFWK4o (ORCPT ); Tue, 23 Jun 2009 06:56:44 -0400 Received: from brick.kernel.dk ([93.163.65.50]:45858 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752195AbZFWK4n (ORCPT ); Tue, 23 Jun 2009 06:56:43 -0400 Date: Tue, 23 Jun 2009 12:56:46 +0200 From: Jens Axboe To: KOSAKI Motohiro Cc: Andrew Morton , Linus Torvalds , Linux Kernel , hch@infradead.org Subject: Re: merging the per-bdi writeback patchset Message-ID: <20090623105645.GX31415@kernel.dk> References: <20090623014835.1fc8fb14.akpm@linux-foundation.org> <20090623085505.GU31415@kernel.dk> <20090623191803.2230.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090623191803.2230.A69D9226@jp.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 23 2009, KOSAKI Motohiro wrote: > Hi > > > On Tue, Jun 23 2009, Andrew Morton wrote: > > > On Tue, 23 Jun 2009 10:11:56 +0200 Jens Axboe wrote: > > > > > > > Things are looking good for this patchset and it's been in -next for > > > > almost a week without any reports of problems. So I'd like to merge it > > > > for 2.6.31 if at all possible. Any objections? > > > > > > erk. I was rather expecting I'd have time to have a look at it all. > > > > OK, we can wait if we have to, just trying to avoid having to keep this > > fresh for one full cycle. I have posted this patchset 11 times though > > over months, so it's not like it's a new piece of work :-) > > > > > It's unclear to me actually _why_ the performance changes which were > > > observed have actually occurred. In fact it's a bit unclear (to me) > > > why the patchset was written and what it sets out to achieve :( > > > > It started out trying to get rid of the pdflush uneven writeout. If you > > look at various pdflush intensive workloads, even on a single disk you > > often have 5 or more pdflush threads working the same device. It's just > > not optimal. Another issue was starvation with request allocation. Given > > that pdflush does non-blocking writes (it has to, by design), pdflush > > can potentially be starved if someone else is working the device. > > Can you please make reproduce program and post mesurement result? > I hope to mesure the same program on my box. For which issue? Lumpy writeout can often be observed just by doing buffered writes to a bunch of files. > Plus, Can you please write more vervose patch description? your patch is a > bit harder review. OK, I can probably improve on that. Do you mean the general description of the patchset, or some of the individual patches? -- Jens Axboe