From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id B68956B0082 for ; Tue, 9 Jun 2009 04:06:19 -0400 (EDT) Received: by gxk28 with SMTP id 28so951649gxk.14 for ; Tue, 09 Jun 2009 01:35:09 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090609172035.DD7C.A69D9226@jp.fujitsu.com> References: <20090609164850.DD73.A69D9226@jp.fujitsu.com> <28c262360906090119r6e881caq9b74028ba43567a7@mail.gmail.com> <20090609172035.DD7C.A69D9226@jp.fujitsu.com> Date: Tue, 9 Jun 2009 17:35:09 +0900 Message-ID: <28c262360906090135x3382456by3518434a9939002b@mail.gmail.com> Subject: Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH mmotm] vmscan: fix may_swap handling for memcg) From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Daisuke Nishimura , LKML , linux-mm , Andrew Morton , Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki , Rik van Riel List-ID: On Tue, Jun 9, 2009 at 5:24 PM, KOSAKI Motohiro wrote: >> On Tue, Jun 9, 2009 at 4:58 PM, KOSAKI >> Motohiro wrote: >> >> Hi, KOSAKI. >> >> >> >> As you know, this problem caused by if condition(priority) in shrink_zone. >> >> Let me have a question. >> >> >> >> Why do we have to prevent scan value calculation when the priority is zero ? >> >> As I know, before split-lru, we didn't do it. >> >> >> >> Is there any specific issue in case of the priority is zero ? >> > >> > Yes. >> > >> > example: >> > >> > get_scan_ratio() return anon:80%, file=20%. and the system have >> > 10000 anon pages and 10000 file pages. >> > >> > shrink_zone() picked up 8000 anon pages and 2000 file pages. >> > it mean 8000 file pages aren't scanned at all. >> > >> > Oops, it can makes OOM-killer although system have droppable file cache. >> > >> Hmm..Can that problem be happen in real system ? >> The file ratio is big means that file lru list scanning is so big but >> rotate is small. >> It means file lru have few reclaimable page. >> >> Isn't it ? I am confusing. >> Could you elaborate, please if you don't mind ? > > hm, ok, my example was wrong. > I intention is, if there are droppable file-back pages (althout only 1 page), > OOM-killer shouldn't occuer. > > many or few is unrelated. > I am not sure that is effective. Have you ever met this problem in real situation ? BTW, I have to dive into code. :) Thanks for spending valuable time for commenting -- Kinds 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