From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754881AbZFWK2X (ORCPT ); Tue, 23 Jun 2009 06:28:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751403AbZFWK2Q (ORCPT ); Tue, 23 Jun 2009 06:28:16 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:54190 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751314AbZFWK2P (ORCPT ); Tue, 23 Jun 2009 06:28:15 -0400 From: KOSAKI Motohiro To: Jens Axboe Subject: Re: merging the per-bdi writeback patchset Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Linus Torvalds , Linux Kernel , hch@infradead.org In-Reply-To: <20090623085505.GU31415@kernel.dk> References: <20090623014835.1fc8fb14.akpm@linux-foundation.org> <20090623085505.GU31415@kernel.dk> Message-Id: <20090623191803.2230.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 23 Jun 2009 19:28:13 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Plus, Can you please write more vervose patch description? your patch is a bit harder review.