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 A22336B00A2 for ; Thu, 11 Mar 2010 00:16:46 -0500 (EST) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2B5GhXG017564 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 11 Mar 2010 14:16:44 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8921545DE7A for ; Thu, 11 Mar 2010 14:16:43 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4154245DE60 for ; Thu, 11 Mar 2010 14:16:43 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id C59741DB803F for ; Thu, 11 Mar 2010 14:16:42 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4DF9AE1800A for ; Thu, 11 Mar 2010 14:16:42 +0900 (JST) Date: Thu, 11 Mar 2010 14:13:00 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH mmotm 2.5/4] memcg: disable irq at page cgroup lock (Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure) Message-Id: <20100311141300.90b85391.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100311135847.990eee62.nishimura@mxp.nes.nec.co.jp> References: <20100308105641.e2e714f4.kamezawa.hiroyu@jp.fujitsu.com> <20100308111724.3e48aee3.nishimura@mxp.nes.nec.co.jp> <20100308113711.d7a249da.kamezawa.hiroyu@jp.fujitsu.com> <20100308170711.4d8b02f0.nishimura@mxp.nes.nec.co.jp> <20100308173100.b5997fd4.kamezawa.hiroyu@jp.fujitsu.com> <20100309001252.GB13490@linux> <20100309091914.4b5f6661.kamezawa.hiroyu@jp.fujitsu.com> <20100309102928.9f36d2bb.nishimura@mxp.nes.nec.co.jp> <20100309045058.GX3073@balbir.in.ibm.com> <20100310104309.c5f9c9a9.nishimura@mxp.nes.nec.co.jp> <20100310035624.GP3073@balbir.in.ibm.com> <20100311133123.ab10183c.nishimura@mxp.nes.nec.co.jp> <20100311134908.48d8b0fc.kamezawa.hiroyu@jp.fujitsu.com> <20100311135847.990eee62.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: balbir@linux.vnet.ibm.com, linux-mm@kvack.org, Andrea Righi , linux-kernel@vger.kernel.org, Trond Myklebust , Suleiman Souhlal , Andrew Morton , containers@lists.linux-foundation.org, Vivek Goyal List-ID: On Thu, 11 Mar 2010 13:58:47 +0900 Daisuke Nishimura wrote: > > I'll consider yet another fix for race in account migration if I can. > > > me too. > How about this ? Assume that the race is very rare. 1. use trylock when updating statistics. If trylock fails, don't account it. 2. add PCG_FLAG for all status as + PCG_ACCT_FILE_MAPPED, /* page is accounted as file rss*/ + PCG_ACCT_DIRTY, /* page is dirty */ + PCG_ACCT_WRITEBACK, /* page is being written back to disk */ + PCG_ACCT_WRITEBACK_TEMP, /* page is used as temporary buffer for FUSE */ + PCG_ACCT_UNSTABLE_NFS, /* NFS page not yet committed to the server */ 3. At reducing counter, check PCG_xxx flags by TESTCLEARPCGFLAG() This is similar to an _used_ method of LRU accounting. And We can think this method's error-range never go too bad number. I think this kind of fuzzy accounting is enough for writeback status. Does anyone need strict accounting ? 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