Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755228Ab0AFEGM (ORCPT ); Tue, 5 Jan 2010 23:06:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754247Ab0AFEGL (ORCPT ); Tue, 5 Jan 2010 23:06:11 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:57396 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751191Ab0AFEGK (ORCPT ); Tue, 5 Jan 2010 23:06:10 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 6 Jan 2010 13:02:58 +0900 From: KAMEZAWA Hiroyuki To: balbir@linux.vnet.ibm.com 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: <20100106130258.a918e047.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100104005030.GG16187@balbir.in.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> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.7.1 (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: 2031 Lines: 56 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. 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/