From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753902AbZDWC4Q (ORCPT ); Wed, 22 Apr 2009 22:56:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752552AbZDWCz7 (ORCPT ); Wed, 22 Apr 2009 22:55:59 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:45182 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752531AbZDWCz7 (ORCPT ); Wed, 22 Apr 2009 22:55:59 -0400 Date: Thu, 23 Apr 2009 11:54:19 +0900 From: KAMEZAWA Hiroyuki To: Theodore Tso 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: <20090423115419.c493266a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090423012254.GZ15541@mit.edu> 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> <20090423012254.GZ15541@mit.edu> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Apr 2009 21:22:54 -0400 Theodore Tso wrote: > 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/O control people should prove it. And they do, I think. > > 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. > It's just a problem of "what we do and what we don't, now". Andrea, Vivek, could you clarify ? As other project, I/O controller will not be 100% at first implementation. > 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....... > yes, then, memcg should have dirty_ratio handler. And, we may have to implement dirty-ratio controller. So, please don't merge memcg discussion and I/O BW throttoling. It's related to each other but different problem. Thanks, -Kame