From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by e28esmtp04.in.ibm.com (8.13.1/8.13.1) with ESMTP id m1KAxFud007469 for ; Wed, 20 Feb 2008 16:29:15 +0530 Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m1KAxFdU712800 for ; Wed, 20 Feb 2008 16:29:15 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.13.1/8.13.3) with ESMTP id m1KAxJsR005664 for ; Wed, 20 Feb 2008 10:59:20 GMT Message-ID: <47BC0704.9010603@linux.vnet.ibm.com> Date: Wed, 20 Feb 2008 16:25:00 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [RFC][PATCH] Clarify mem_cgroup lock handling and avoid races. References: <20080219215431.1aa9fa8a.kamezawa.hiroyu@jp.fujitsu.com> <47BBC15E.5070405@linux.vnet.ibm.com> <20080220.185821.61784723.taka@valinux.co.jp> <6599ad830802200206w23955c9cn26bf768e790a6161@mail.gmail.com> <47BBFCC2.5020408@linux.vnet.ibm.com> <6599ad830802200218t41c70455u5d008c605e8b9762@mail.gmail.com> In-Reply-To: <6599ad830802200218t41c70455u5d008c605e8b9762@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Paul Menage Cc: Hirokazu Takahashi , hugh@veritas.com, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, yamamoto@valinux.co.jp, riel@redhat.com List-ID: Paul Menage wrote: > On Feb 20, 2008 2:11 AM, Balbir Singh wrote: >> Dynamically turning on/off the memory controller, can/will lead to accounting >> issues and deficiencies, since the memory controller would now have no idea of >> how much memory has been allocated by which cgroup. >> > > A cgroups subsystem can only be unbound from its hierarchy when there > are no child cgroups of the root cgroup in that hierarchy. So this > shouldn't be too much of a problem - when this transition occurs, all > tasks are in the same group, and no other groups exist. > > Paul Yes, I agree, but then at the point of unbinding them, tasks could have already allocated several pages to their RSS or brought in pages into the page cache. Accounting from this state is not so straight forward and will lead to more complexity in code. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org