From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zps75.corp.google.com (zps75.corp.google.com [172.25.146.75]) by smtp-out.google.com with ESMTP id m1KBtJ5h003617 for ; Wed, 20 Feb 2008 03:55:19 -0800 Received: from py-out-1112.google.com (pygw53.prod.google.com [10.34.224.53]) by zps75.corp.google.com with ESMTP id m1KBtI8o011244 for ; Wed, 20 Feb 2008 03:55:19 -0800 Received: by py-out-1112.google.com with SMTP id w53so3205926pyg.25 for ; Wed, 20 Feb 2008 03:55:18 -0800 (PST) Message-ID: <6599ad830802200355v40bf8b81re32c24cefad0b279@mail.gmail.com> Date: Wed, 20 Feb 2008 03:55:18 -0800 From: "Paul Menage" Subject: Re: [RFC][PATCH] Clarify mem_cgroup lock handling and avoid races. In-Reply-To: <47BC10A8.4020508@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080219215431.1aa9fa8a.kamezawa.hiroyu@jp.fujitsu.com> <47BBC15E.5070405@linux.vnet.ibm.com> <20080220.185821.61784723.taka@valinux.co.jp> <47BC10A8.4020508@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: Hirokazu Takahashi , hugh@veritas.com, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, yamamoto@valinux.co.jp, riel@redhat.com List-ID: On Feb 20, 2008 3:36 AM, Balbir Singh wrote: > > > > And you may possibly have a chance to remove page->page_cgroup member > > if you allocate array of page_cgroups and attach them to the zone which > > the pages belong to. > > > > We thought of this as well. We dropped it, because we need to track only user > pages at the moment. Doing it for all pages means having the overhead for each > page on the system. > While having an array of page_cgroup objects may or may not be a good idea, I'm not sure that the overhead argument against them is a very good one. I suspect that on most systems that want to use the cgroup memory controller, user-allocated pages will fill the vast majority of memory. So using the arrays and eliminating the extra pointer in struct page would actually reduce overhead. Paul -- 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