From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by wx-out-0506.google.com with SMTP id h31so16056wxd.11 for ; Thu, 21 Feb 2008 04:29:31 -0800 (PST) Message-ID: <44c63dc40802210429y24757a34p2cc8093a2db6181a@mail.gmail.com> Date: Thu, 21 Feb 2008 21:29:30 +0900 From: "minchan Kim" Subject: Re: [RFC][PATCH] the proposal of improve page reclaim by throttle In-Reply-To: <2f11576a0802210255k1e3acad7n87814e916fd24509@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080220181447.6444.KOSAKI.MOTOHIRO@jp.fujitsu.com> <44c63dc40802200149r6b03d970g2fbde74b85ad5443@mail.gmail.com> <20080220185648.6447.KOSAKI.MOTOHIRO@jp.fujitsu.com> <44c63dc40802210138s100e921ekde01b30bae13beb1@mail.gmail.com> <2f11576a0802210255k1e3acad7n87814e916fd24509@mail.gmail.com> Sender: owner-linux-mm@kvack.org Return-Path: To: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki , Balbir Singh , Rik van Riel , Lee Schermerhorn , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Thu, Feb 21, 2008 at 7:55 PM, KOSAKI Motohiro wrote: > Hi Kim-san, > > Thank you very much. > btw, what different between and ? have no swap device with 200 tasks by hackbench. But have swap device(32M) with 240 tasks by hackbench. If have no swap device without your patch, is killed by OOM. - NO SWAP Running with 5*40 (== 200) tasks. ... - SWAP Running with 6*40 (== 240) tasks. ... > > > It was a very interesting result. > > In embedded system, your patch improve performance a little in case > > without noswap(normal case in embedded system). > > But, more important thing is OOM occured when I made 240 process > > without swap device and vanilla kernel. > > Then, I applied your patch, it worked very well without OOM. > > Wow, it is very interesting result! > I am very happy. > > > > I think that's why zone's page_scanned was six times greater than > > number of lru pages. > > At result, OOM happened. > > please repost question with change subject. > i don't know reason of vanilla kernel behavior, sorry. Normally, embedded linux have only one zone(DMA). If your patch isn't applied, several processes can reclaim memory in parallel. then, DMA zone's pages_scanned is suddenly increased largely. Because embedded linux have no swap device, kernel can't stop to scan lru list until meeting page cache page. so if zone->pages_scanned is greater six time than lru list pages, kernel make the zone with unreclaimable state, As a result, OOM will kill it, too. -- Thanks, barrios -- 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