From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755429AbZBCPRA (ORCPT ); Tue, 3 Feb 2009 10:17:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753068AbZBCPQv (ORCPT ); Tue, 3 Feb 2009 10:16:51 -0500 Received: from e28smtp04.in.ibm.com ([59.145.155.4]:48616 "EHLO e28smtp04.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752857AbZBCPQv (ORCPT ); Tue, 3 Feb 2009 10:16:51 -0500 Date: Tue, 3 Feb 2009 20:46:36 +0530 From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: Andrew Morton , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "lizf@cn.fujitsu.com" , "linux-mm@kvack.org" Subject: Re: [-mm patch] Show memcg information during OOM (v2) Message-ID: <20090203151635.GC918@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090203072013.GU918@balbir.in.ibm.com> <20090203072701.GV918@balbir.in.ibm.com> <20090203170427.c6070cda.kamezawa.hiroyu@jp.fujitsu.com> <20090203101921.GY918@balbir.in.ibm.com> <20090203192819.0c1e0544.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090203192819.0c1e0544.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * KAMEZAWA Hiroyuki [2009-02-03 19:28:19]: > On Tue, 3 Feb 2009 15:49:21 +0530 > Balbir Singh wrote: > > > * KAMEZAWA Hiroyuki [2009-02-03 17:04:27]: > > > > > On Tue, 3 Feb 2009 12:57:01 +0530 > > > Balbir Singh wrote: > > > > > > > Checkpatch caught an additional space, so here is the patch again > > > > > > > > > > > > Description: Add RSS and swap to OOM output from memcg > > > > > > > > From: Balbir Singh > > > > > > > > Changelog v2..v1: > > > > > > > > 1. Add more information about task's memcg and the memcg > > > > over it's limit > > > > 2. Print data in KB > > > > 3. Move the print routine outside task_lock() > > > > 4. Use rcu_read_lock() around cgroup_path, strictly speaking it > > > > is not required, but relying on the current memcg implementation > > > > is not a good idea. > > > > > > > > > > > > This patch displays memcg values like failcnt, usage and limit > > > > when an OOM occurs due to memcg. > > > > > > > > Thanks go out to Johannes Weiner, Li Zefan, David Rientjes, > > > > Kamezawa Hiroyuki, Daisuke Nishimura and KOSAKI Motohiro for > > > > review. > > > > > > > > > > IIUC, this oom_kill is serialized by memcg_tasklist mutex. > > > Then, you don't have to allocate buffer on stack. > > > > > > > > > > +void mem_cgroup_print_mem_info(struct mem_cgroup *memcg, struct task_struct *p) > > > > +{ > > > > + struct cgroup *task_cgrp; > > > > + struct cgroup *mem_cgrp; > > > > + /* > > > > + * Need a buffer on stack, can't rely on allocations. > > > > + */ > > > > + char task_memcg_name[MEM_CGROUP_OOM_BUF_SIZE]; > > > > + char memcg_name[MEM_CGROUP_OOM_BUF_SIZE]; > > > > + int ret; > > > > + > > > > > > making this as > > > > > > static char task_memcg_name[PATH_MAX]; > > > static char memcg_name[PATH_MAX]; > > > > > > is ok, I think. and the patch will be more simple. > > > > > > > I am having second thoughts about this one. It introduces a standard > > overhead of 2 pages on x86*, while the first one will work for most > > cases and all the overhead is on stack, which disappears quickly. > > That is the reason I did not do it in the first place and put it as a > > NOTE. > > > But *128* is tooooooo short ;) > And, your patch makes "OOM Message Format" unstable. > >From system administration view, it's unacceptable. > Not printing name at all is better than "printed out sometimes you lucky" > OK, I have the code with PATH_MAX ready. I'll send that out. -- Balbir