From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 20 Feb 2008 20:21:43 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH] Clarify mem_cgroup lock handling and avoid races. Message-Id: <20080220202143.4cc2fc05.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <47BC0704.9010603@linux.vnet.ibm.com> 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> <47BC0704.9010603@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: Paul Menage , Hirokazu Takahashi , hugh@veritas.com, linux-mm@kvack.org, yamamoto@valinux.co.jp, riel@redhat.com List-ID: On Wed, 20 Feb 2008 16:25:00 +0530 Balbir Singh wrote: > 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. unbind -> force_empty can't work ? Thanks, -Kame -- 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