From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754935AbYHUFPt (ORCPT ); Thu, 21 Aug 2008 01:15:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753237AbYHUFP1 (ORCPT ); Thu, 21 Aug 2008 01:15:27 -0400 Received: from TYO202.gate.nec.co.jp ([202.32.8.206]:45348 "EHLO tyo202.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753130AbYHUFP0 (ORCPT ); Thu, 21 Aug 2008 01:15:26 -0400 Date: Thu, 21 Aug 2008 12:54:18 +0900 From: Daisuke Nishimura To: KAMEZAWA Hiroyuki Cc: nishimura@mxp.nes.nec.co.jp, LKML , "balbir@linux.vnet.ibm.com" , "yamamoto@valinux.co.jp" , ryov@valinux.co.jp, "linux-mm@kvack.org" Subject: Re: [RFC][PATCH -mm 0/7] memcg: lockless page_cgroup v1 Message-Id: <20080821125418.741b826b.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20080821111740.49f99038.kamezawa.hiroyu@jp.fujitsu.com> References: <20080819173014.17358c17.kamezawa.hiroyu@jp.fujitsu.com> <20080820185306.e897c512.kamezawa.hiroyu@jp.fujitsu.com> <20080820194108.e76b20b3.kamezawa.hiroyu@jp.fujitsu.com> <20080820200006.a152c14c.kamezawa.hiroyu@jp.fujitsu.com> <20080821111740.49f99038.kamezawa.hiroyu@jp.fujitsu.com> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 21 Aug 2008 11:17:40 +0900, KAMEZAWA Hiroyuki wrote: > On Wed, 20 Aug 2008 20:00:06 +0900 > KAMEZAWA Hiroyuki wrote: > > > On Wed, 20 Aug 2008 19:41:08 +0900 > > KAMEZAWA Hiroyuki wrote: > > > > > On Wed, 20 Aug 2008 18:53:06 +0900 > > > KAMEZAWA Hiroyuki wrote: > > > > > > > Hi, this is a patch set for lockless page_cgroup. > > > > > > > > dropped patches related to mem+swap controller for easy review. > > > > (I'm rewriting it, too.) > > > > > > > > Changes from current -mm is. > > > > - page_cgroup->flags operations is set to be atomic. > > > > - lock_page_cgroup() is removed. > > > > - page->page_cgroup is changed from unsigned long to struct page_cgroup* > > > > - page_cgroup is freed by RCU. > > > > - For avoiding race, charge/uncharge against mm/memory.c::insert_page() is > > > > omitted. This is ususally used for mapping device's page. (I think...) > > > > > > > > In my quick test, perfomance is improved a little. But the benefit of this > > > > patch is to allow access page_cgroup without lock. I think this is good > > > > for Yamamoto's Dirty page tracking for memcg. > > > > For I/O tracking people, I added a header file for allowing access to > > > > page_cgroup from out of memcontrol.c > > > > > > > > The base kernel is recent mmtom. Any comments are welcome. > > > > This is still under test. I have to do long-run test before removing "RFC". > > > > > > > Known problem: force_emtpy is broken...so rmdir will struck into nightmare. > > > It's because of patch 2/7. > > > will be fixed in the next version. > > > > > > > This is a quick fix but I think I can find some better solution.. > > == > > Because removal from LRU is delayed, mz->lru will never be empty until > > someone kick drain. This patch rotate LRU while force_empty and makes > > page_cgroup will be freed. > > > > I'd like to rewrite force_empty to move all usage to "default" cgroup. > There are some reasons. > > 1. current force_empty creates an alive page which has no page_cgroup. > This is bad for routine which want to access page_cgroup from page. > And this behavior will be an issue of race condition in future. I agree that current force_empty is not good in this point. > 2. We can see amount of out-of-control usage in default cgroup. > > But to do this, I'll have to avoid "hitting limit" in default cgroup. > I'm now wondering to make it impossible to set limit to default cgroup. > (will show as a patch in the next version of series.) > Does anyone have an idea ? > I don't have a strong objection about setting default cgroup unlimited and moving usages to default cgroup. But I think this is related to hierarchy support as Balbir-san says. And, setting default cgroup unlimited would not be so strange if hierarchy is supported. Thanks, Daisuke Nishimura.