From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753868AbYIXIda (ORCPT ); Wed, 24 Sep 2008 04:33:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752721AbYIXIdQ (ORCPT ); Wed, 24 Sep 2008 04:33:16 -0400 Received: from E23SMTP05.au.ibm.com ([202.81.18.174]:44994 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752136AbYIXIdO (ORCPT ); Wed, 24 Sep 2008 04:33:14 -0400 Message-ID: <48D9FAFF.8070404@linux.vnet.ibm.com> Date: Wed, 24 Sep 2008 01:31:59 -0700 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com Organization: IBM User-Agent: Thunderbird 2.0.0.16 (X11/20080725) MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: "linux-mm@kvack.org" , "nishimura@mxp.nes.nec.co.jp" , "xemul@openvz.org" , LKML Subject: Re: [PATCH 9/13] memcg: lookup page cgroup (and remove pointer from struct page) References: <20080922195159.41a9d2bc.kamezawa.hiroyu@jp.fujitsu.com> <20080922201206.e73d9ce6.kamezawa.hiroyu@jp.fujitsu.com> <20080924084839.f5901719.kamezawa.hiroyu@jp.fujitsu.com> <661de9470809231909h24ca4a39k470e322f2c1019dc@mail.gmail.com> <20080924120940.5aea6907.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080924120940.5aea6907.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 Wed, 24 Sep 2008 07:39:58 +0530 > "Balbir Singh" wrote: >>> I'll add FLATMEM/DISCONTIGMEM/SPARSEMEM support directly. >>> I already have wasted a month on this not-interesting work and want to fix >>> this soon. >>> >> Let's look at the basic requirement, make memory resource controller >> not suck with 32 bit systems. I have been thinking of about removing >> page_cgroup from struct page only for 32 bit systems (use radix tree), >> 32 bit systems can have a maximum of 64GB if PAE is enabled, I suspect >> radix tree should work there and let the 64 bit systems work as is. If >> performance is an issue, I would recommend the 32 bit folks upgrade to >> 64 bit :) Can we build consensus around this approach? >> > My thinking is below. (assume 64bit) > assume 64 bit for the calculations below? > - remove page_cgroup pointer from struct page allows us to reduce > static memory usage at boot by 8bytes/4096bytes if memory cgroup is disabled. > This reaches 96MB on my 48 GB box. I think this is big. > - pre-allocation of page_cgroup gives us following. > Pros. > - We are not necessary to be afraid of "failure of kmalloc" and > "goes down to memory reclaim at kmalloc" > This makes memory resource controller much simpler and robust. > - We can know what amount of kernel memory will be used for > LRU pages management. > Cons. > - All page_cgroups are allocated at boot. > This reaches 480MB on my 48GB box. > > But I think we can ignore "Cons.". If we use up memory, we'll use tons of > page_cgroup. Considering memory fragmentation caused by allocating a lots of > very small object, pre-allocation makes memcg better. This looks like a good patch. I'll review and test it. -- Balbir