Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752092Ab1CKDUQ (ORCPT ); Thu, 10 Mar 2011 22:20:16 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:44813 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751272Ab1CKDUO (ORCPT ); Thu, 10 Mar 2011 22:20:14 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 11 Mar 2011 12:13:43 +0900 From: KAMEZAWA Hiroyuki To: Vivek Goyal Cc: Dave Chinner , Chris Mason , Andreas Dilger , Justin TerAvest , m-ikeda , jaxboe , linux-kernel , ryov , taka , "righi.andrea" , guijianfeng , balbir , ctalbott , nauman , mrubin , linux-fsdevel Subject: Re: [RFC] Storing cgroup id in page->private (Was: Re: [RFC] [PATCH 0/6] Provide cgroup isolation for buffered writes.) Message-Id: <20110311121343.23c61461.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110311031503.GC11710@redhat.com> References: <20110310191115.GG29464@redhat.com> <20110310194106.GH29464@redhat.com> <1299791640-sup-1874@think> <3EC7D30A-B8F7-416B-8B1D-A19350C57D82@dilger.ca> <20110310213832.GK29464@redhat.com> <1299793340-sup-9066@think> <20110311014618.GC15097@dastard> <20110311021531.GA11710@redhat.com> <20110311115235.3663792c.kamezawa.hiroyu@jp.fujitsu.com> <20110311031503.GC11710@redhat.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.1.0 (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 Content-Length: 1923 Lines: 52 On Thu, 10 Mar 2011 22:15:04 -0500 Vivek Goyal wrote: > On Fri, Mar 11, 2011 at 11:52:35AM +0900, KAMEZAWA Hiroyuki wrote: > > On Thu, 10 Mar 2011 21:15:31 -0500 > > Vivek Goyal wrote: > > > > > > IMO, if you really need some per-page information, then just put it > > > > in the struct page - you can't hide the memory overhead just by > > > > having the filesystem to store it for you. That just adds > > > > unnecessary complexity... > > > > > > Ok. I guess adding anything to struct page is going to be hard and > > > we might have to fall back to looking into using page_cgroup for > > > tracking page state. I was trying to explore the ways so that we don't > > > have to instantiate whole page_cgroup structure just for trying > > > to figure out who dirtied the page. > > > > > > > Is this bad ? > > == > > Sounds like an interesting idea. I am primarily concered about the radix > tree node size increase. Not sure how big a concern this is. > > Also tracking is useful for two things. > > - Proportinal IO > - IO throttling > > For proportional IO, anyway we have to use it with memory controller to > control per cgroup dirty ratio so storing info in page_cgroup should > not hurt. > dirty-ratio for memcg will be implemented. It's definitely necessary. > The only other case where dependence on page_cgroup hurts is IO throttling > where IO controller does not really need memory cgroup controller (I hope > so). But we are still not sure if throttling IO at device level is a > good idea and how to resolve issues related to priority inversion. > Yes, that's priority inversion is my concern. Thanks, -Kame -- 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/