Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752552AbZDWB0o (ORCPT ); Wed, 22 Apr 2009 21:26:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751432AbZDWB0e (ORCPT ); Wed, 22 Apr 2009 21:26:34 -0400 Received: from THUNK.ORG ([69.25.196.29]:50238 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbZDWB0e (ORCPT ); Wed, 22 Apr 2009 21:26:34 -0400 Date: Wed, 22 Apr 2009 21:22:54 -0400 From: Theodore Tso To: KAMEZAWA Hiroyuki Cc: Andrea Righi , randy.dunlap@oracle.com, Carl Henrik Lunde , Jens Axboe , eric.rannaud@gmail.com, Balbir Singh , fernando@oss.ntt.co.jp, dradford@bluehost.com, Gui@smtp1.linux-foundation.org, agk@sourceware.org, subrata@linux.vnet.ibm.com, Paul Menage , akpm@linux-foundation.org, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dave@linux.vnet.ibm.com, matt@bluehost.com, roberto@unbit.it, ngupta@google.com Subject: Re: [PATCH 9/9] ext3: do not throttle metadata and journal IO Message-ID: <20090423012254.GZ15541@mit.edu> Mail-Followup-To: Theodore Tso , KAMEZAWA Hiroyuki , Andrea Righi , randy.dunlap@oracle.com, Carl Henrik Lunde , Jens Axboe , eric.rannaud@gmail.com, Balbir Singh , fernando@oss.ntt.co.jp, dradford@bluehost.com, Gui@smtp1.linux-foundation.org, agk@sourceware.org, subrata@linux.vnet.ibm.com, Paul Menage , akpm@linux-foundation.org, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dave@linux.vnet.ibm.com, matt@bluehost.com, roberto@unbit.it, ngupta@google.com References: <20090421163537.GI19186@mit.edu> <20090421172317.GM19637@balbir.in.ibm.com> <20090421174620.GD15541@mit.edu> <20090421181429.GO19637@balbir.in.ibm.com> <20090421191401.GF15541@mit.edu> <20090421204905.GA5573@linux> <20090422093349.1ee9ae82.kamezawa.hiroyu@jp.fujitsu.com> <20090422102153.9aec17b9.kamezawa.hiroyu@jp.fujitsu.com> <20090422102239.GA1935@linux> <20090423090535.ec419269.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090423090535.ec419269.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@mit.edu X-SA-Exim-Scanned: No (on thunker.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1618 Lines: 40 On Thu, Apr 23, 2009 at 09:05:35AM +0900, KAMEZAWA Hiroyuki wrote: > So, current status is. > > A. memcg should support dirty_ratio for its own memory reclaim. > in plan. > > B. another cgroup can be implemnted to support cgroup_dirty_limit(). > But relationship with "A" should be discussed. > no plan yet. > > C. I/O cgroup and bufferred I/O tracking system. > Now under patch review. > > And this I/O throttle is mainly for "C" discussion. How much testing has been done in terms of whether the I/O throttling actually works? Not just, "the kernel doesn't crash", but that where you have one process generating a large amount of I/O load, in various different ways, and whether the right things happens? If so, how has this been measured? I'm really concerned that given some of the ways that I/O will "leak" out --- the via pdflush, swap writeout, etc., that without the rest of the pieces in place, I/O throttling by itself might not prove to be very effective. Sure, if the workload is only doing direct I/O, life is pretty easy and it shouldn't be hard to throttle the cgroup. But in the case where there is bufferred I/O, without write throttling, it's hard to see how well the I/O controller will work in practice. In fact, I wouldn't be that surprised if it's possible to trigger the OOM killer....... Regards, - Ted -- 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/