From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 2F62B6B006A for ; Wed, 14 Jan 2009 23:42:26 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n0F4gK7L013396 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 15 Jan 2009 13:42:20 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 1000645DD81 for ; Thu, 15 Jan 2009 13:42:20 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id CF67245DD7B for ; Thu, 15 Jan 2009 13:42:19 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 72F551DB8045 for ; Thu, 15 Jan 2009 13:42:19 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id E9A431DB8041 for ; Thu, 15 Jan 2009 13:42:18 +0900 (JST) Date: Thu, 15 Jan 2009 13:41:14 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][PATCH 5/4] memcg: don't call res_counter_uncharge when obsolete Message-Id: <20090115134114.dba6b83a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090115041750.GE21516@balbir.in.ibm.com> References: <20090113184533.6ffd2af9.nishimura@mxp.nes.nec.co.jp> <20090114175121.275ecd59.nishimura@mxp.nes.nec.co.jp> <20090114135539.GA21516@balbir.in.ibm.com> <20090115122416.e15d88a7.kamezawa.hiroyu@jp.fujitsu.com> <20090115041750.GE21516@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Daisuke Nishimura , LKML , linux-mm , Andrew Morton , Pavel Emelyanov , Li Zefan , Paul Menage List-ID: On Thu, 15 Jan 2009 09:47:50 +0530 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2009-01-15 12:24:16]: > > But I don't like -EBUSY ;) > > > > When rmdir() returns -EBUSY even if there are no (visible) children and tasks, > > our customer will take kdump and send it to me "please explain this kernel bug" > > > > I'm sure it will happen ;) > > > > OK, but memory.stat can show why the group is busy and with > move_to_parent() such issues should not occur right? I'll relook at > the code. Thanks for your input. > There was a design choice at swap_cgroup. At rmdir, there may be used swap entry in memcg. (mem->memsw.usage can be > 0) 1. update all records in swap cgroup 2. just ignore account from swap, we can treat then at swap-in. I implemented "2" by refcnt. To do "1", we have to scan all used swap_cgroup but I don't want to scan all swap_cgroup entry at rmdir. It's heavy job. (*) To reduce memory usage by swap_cgroup, swap_cgroup just have a pointer to memcg (**) I implemented swap_cgroup as statically allocated array because I don't want any dynamic memory allocation at swap-out and want to avoid unnecessary memory usage. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org