Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755962AbZDUU2Y (ORCPT ); Tue, 21 Apr 2009 16:28:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752437AbZDUU2P (ORCPT ); Tue, 21 Apr 2009 16:28:15 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:35140 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752777AbZDUU2O (ORCPT ); Tue, 21 Apr 2009 16:28:14 -0400 Date: Tue, 21 Apr 2009 13:25:51 -0700 From: Andrew Morton To: balbir@linux.vnet.ibm.com Cc: kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Add file based RSS accounting for memory resource controller (v3) Message-Id: <20090421132551.38e9960a.akpm@linux-foundation.org> In-Reply-To: <20090417141837.GD3896@balbir.in.ibm.com> References: <20090416120316.GG7082@balbir.in.ibm.com> <20090417091459.dac2cc39.kamezawa.hiroyu@jp.fujitsu.com> <20090417014042.GB18558@balbir.in.ibm.com> <20090417110350.3144183d.kamezawa.hiroyu@jp.fujitsu.com> <20090417034539.GD18558@balbir.in.ibm.com> <20090417124951.a8472c86.kamezawa.hiroyu@jp.fujitsu.com> <20090417045623.GA3896@balbir.in.ibm.com> <20090417141726.a69ebdcc.kamezawa.hiroyu@jp.fujitsu.com> <20090417064726.GB3896@balbir.in.ibm.com> <20090417155608.eeed1f02.kamezawa.hiroyu@jp.fujitsu.com> <20090417141837.GD3896@balbir.in.ibm.com> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) 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 Content-Length: 2746 Lines: 76 On Fri, 17 Apr 2009 19:48:38 +0530 Balbir Singh wrote: > > ... > > We currently don't track file RSS, the RSS we report is actually anon RSS. > All the file mapped pages, come in through the page cache and get accounted > there. This patch adds support for accounting file RSS pages. It should > > 1. Help improve the metrics reported by the memory resource controller > 2. Will form the basis for a future shared memory accounting heuristic > that has been proposed by Kamezawa. > > Unfortunately, we cannot rename the existing "rss" keyword used in memory.stat > to "anon_rss". We however, add "mapped_file" data and hope to educate the end > user through documentation. > > Signed-off-by: Balbir Singh > > ... > > @@ -1096,6 +1135,10 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, > struct mem_cgroup_per_zone *from_mz, *to_mz; > int nid, zid; > int ret = -EBUSY; > + struct page *page; > + int cpu; > + struct mem_cgroup_stat *stat; > + struct mem_cgroup_stat_cpu *cpustat; > > VM_BUG_ON(from == to); > VM_BUG_ON(PageLRU(pc->page)); > @@ -1116,6 +1159,23 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, > > res_counter_uncharge(&from->res, PAGE_SIZE); > mem_cgroup_charge_statistics(from, pc, false); > + > + page = pc->page; > + if (page_is_file_cache(page) && page_mapped(page)) { > + cpu = smp_processor_id(); > + /* Update mapped_file data for mem_cgroup "from" */ > + stat = &from->stat; > + cpustat = &stat->cpustat[cpu]; > + __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_MAPPED_FILE, > + -1); > + > + /* Update mapped_file data for mem_cgroup "to" */ > + stat = &to->stat; > + cpustat = &stat->cpustat[cpu]; > + __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_MAPPED_FILE, > + 1); > + } This function (mem_cgroup_move_account()) does a trylock_page_cgroup() and if that fails it will bale out, and the newly-added code will not be executed. What are the implications of this? Does the missed accounting later get performed somewhere, or does the error remain in place? That trylock_page_cgroup() really sucks - trylocks usually do. Could someone please raise a patch which completely documents the reasons for its presence, and for any other uncommented/unobvious trylocks? Where appropriate, the comment should explain why the trylock isn't simply a bug - why it is safe and correct to omit the operations which we wished to perform. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/