From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753730AbYIADm7 (ORCPT ); Sun, 31 Aug 2008 23:42:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751189AbYIADmu (ORCPT ); Sun, 31 Aug 2008 23:42:50 -0400 Received: from E23SMTP04.au.ibm.com ([202.81.18.173]:45425 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053AbYIADmu (ORCPT ); Sun, 31 Aug 2008 23:42:50 -0400 Message-ID: <48BB64B5.4060208@linux.vnet.ibm.com> Date: Mon, 01 Sep 2008 09:12:45 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 2.0.0.16 (X11/20080724) MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: Andrew Morton , hugh@veritas.com, menage@google.com, xemul@openvz.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC][PATCH] Remove cgroup member from struct page References: <20080831174756.GA25790@balbir.in.ibm.com> <20080901113918.b6f05ca6.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080901113918.b6f05ca6.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KAMEZAWA Hiroyuki wrote: > On Sun, 31 Aug 2008 23:17:56 +0530 > Balbir Singh wrote: > >> This is a rewrite of a patch I had written long back to remove struct page >> (I shared the patches with Kamezawa, but never posted them anywhere else). >> I spent the weekend, cleaning them up for 2.6.27-rc5-mmotm (29 Aug 2008). >> >> I've tested the patches on an x86_64 box, I've run a simple test running >> under the memory control group and the same test running concurrently under >> two different groups (and creating pressure within their groups). I've also >> compiled the patch with CGROUP_MEM_RES_CTLR turned off. >> >> Advantages of the patch >> >> 1. It removes the extra pointer in struct page >> >> Disadvantages >> >> 1. It adds an additional lock structure to struct page_cgroup >> 2. Radix tree lookup is not an O(1) operation, once the page is known >> getting to the page_cgroup (pc) is a little more expensive now. >> >> This is an initial RFC for comments >> >> TODOs >> >> 1. Test the page migration changes >> 2. Test the performance impact of the patch/approach >> >> Comments/Reviews? >> > BTW, how deep this radix-tree on 4GB/32GB/64GB/256GB machine ? Good Question, My ball-park estimates are number of pfns = RADIX_TREE_TAG_LONGS/(RADIX_TREE_TAG_LONGS - 1) * (RADIX_TREE_LONGS^n - 1) and "n" is the number we are looking for. For a 64 bit system with 256 GB and 4KB page size, I've calculated it to be 9 levels deep. -- Balbir