From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id E17336B007B for ; Sun, 17 Jan 2010 21:25:11 -0500 (EST) Received: by pwj10 with SMTP id 10so1790596pwj.6 for ; Sun, 17 Jan 2010 18:25:10 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4B53C466.4010103@redhat.com> References: <20100118100359.AE22.A69D9226@jp.fujitsu.com> <28c262361001171747w450c8fd8j4daf84b72fb68e1a@mail.gmail.com> <20100118104910.AE2D.A69D9226@jp.fujitsu.com> <28c262361001171810w544614b7rdd3df0f984692f35@mail.gmail.com> <4B53C466.4010103@redhat.com> Date: Mon, 18 Jan 2010 11:25:10 +0900 Message-ID: <28c262361001171825l59e8ecbemd30a628cd36aab01@mail.gmail.com> Subject: Re: [PATCH 2/3][v2] vmstat: add anon_scan_ratio field to zoneinfo From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Rik van Riel Cc: KOSAKI Motohiro , LKML , linux-mm , Andrew Morton , Balbir Singh , KAMEZAWA Hiroyuki List-ID: On Mon, Jan 18, 2010 at 11:16 AM, Rik van Riel wrote: > On 01/17/2010 09:10 PM, Minchan Kim wrote: > >> Absoultely right. I missed that. Thanks. >> get_scan_ratio used lru_lock to get reclaim_stat->recent_xxxx. >> But, it doesn't used lru_lock to get ap/fp. >> >> Is it intentional? I think you or Rik know it. :) >> I think if we want to get exact value, we have to use lru_lock until >> getting ap/fp. >> If it isn't, we don't need lru_lock when we get the >> reclaim_stat->recent_xxxx. >> >> What do you think about it? > > This is definately not intentional. > > Getting race conditions in this code could throw off the > statistics by a factor 2. =C2=A0I do not know how serious that > would be for the VM or whether (and how quickly) it would > self correct. Okay. How about making patch to get exact ap/fp? Although it were not serious or fast recoverable, I think it would be bette= r to protect lru_lock for consistency if lru_lock isn't big contention lock. > > -- > All rights reversed. > --=20 Kind regards, Minchan Kim -- 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