Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754944Ab0AFHCA (ORCPT ); Wed, 6 Jan 2010 02:02:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752367Ab0AFHB7 (ORCPT ); Wed, 6 Jan 2010 02:01:59 -0500 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:35932 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751164Ab0AFHB7 (ORCPT ); Wed, 6 Jan 2010 02:01:59 -0500 Date: Wed, 6 Jan 2010 12:31:50 +0530 From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , Andrew Morton , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" Subject: Re: [RFC] Shared page accounting for memory cgroup Message-ID: <20100106070150.GL3059@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20091229182743.GB12533@balbir.in.ibm.com> <20100104085108.eaa9c867.kamezawa.hiroyu@jp.fujitsu.com> <20100104000752.GC16187@balbir.in.ibm.com> <20100104093528.04846521.kamezawa.hiroyu@jp.fujitsu.com> <20100104005030.GG16187@balbir.in.ibm.com> <20100106130258.a918e047.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20100106130258.a918e047.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2346 Lines: 62 * KAMEZAWA Hiroyuki [2010-01-06 13:02:58]: > On Mon, 4 Jan 2010 06:20:31 +0530 > Balbir Singh wrote: > > > * KAMEZAWA Hiroyuki [2010-01-04 09:35:28]: > > > > > On Mon, 4 Jan 2010 05:37:52 +0530 > > > Balbir Singh wrote: > > > > > > > * KAMEZAWA Hiroyuki [2010-01-04 08:51:08]: > > > > > > > > > On Tue, 29 Dec 2009 23:57:43 +0530 > > > > > Balbir Singh wrote: > > > > > > > > > > > Hi, Everyone, > > > > > > > > > > > > I've been working on heuristics for shared page accounting for the > > > > > > memory cgroup. I've tested the patches by creating multiple cgroups > > > > > > and running programs that share memory and observed the output. > > > > > > > > > > > > Comments? > > > > > > > > > > Hmm? Why we have to do this in the kernel ? > > > > > > > > > > > > > For several reasons that I can think of > > > > > > > > 1. With task migration changes coming in, getting consistent data free of races > > > > is going to be hard. > > > > > > Hmm, Let's see real-worlds's "ps" or "top" command. Even when there are no guarantee > > > of error range of data, it's still useful. > > > > Yes, my concern is this > > > > 1. I iterate through tasks and calculate RSS > > 2. I look at memory.usage_in_bytes > > > > If the time in user space between 1 and 2 is large I get very wrong > > results, specifically if the workload is changing its memory usage > > drastically.. no? > > > No. If it takes long time, locking fork()/exit() for such long time is the bigger > issue. > I recommend you to add memacct subsystem to sum up RSS of all processes's RSS counting > under a cgroup. Althoght it may add huge costs in page fault path but implementation > will be very simple and will not hurt realtime ops. > There will be no terrible race, I guess. > But others hold that lock as well, simple thing like listing tasks and moving tasks, etc. I expect the usage of shared to be in the same range. -- Balbir -- 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/