From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 98A466B01E3 for ; Thu, 15 Apr 2010 00:32:55 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o3F4Wq0s007337 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 15 Apr 2010 13:32:53 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 6AD2145DE53 for ; Thu, 15 Apr 2010 13:32:52 +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 39D8F45DE4D for ; Thu, 15 Apr 2010 13:32:52 +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 0BE001DB8044 for ; Thu, 15 Apr 2010 13:32:52 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 85C871DB8042 for ; Thu, 15 Apr 2010 13:32:51 +0900 (JST) From: KOSAKI Motohiro Subject: Re: 32GB SSD on USB1.1 P3/700 == ___HELL___ (2.6.34-rc3) In-Reply-To: <20100415041931.GA14215@localhost> References: <20100415122928.D168.A69D9226@jp.fujitsu.com> <20100415041931.GA14215@localhost> Message-Id: <20100415132312.D180.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Thu, 15 Apr 2010 13:32:50 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: kosaki.motohiro@jp.fujitsu.com, Andreas Mohr , Jens Axboe , Minchan Kim , Linux Memory Management List , "linux-kernel@vger.kernel.org" , Rik van Riel List-ID: > On Thu, Apr 15, 2010 at 11:31:52AM +0800, KOSAKI Motohiro wrote: > > > > Many applications (this one and below) are stuck in > > > > wait_on_page_writeback(). I guess this is why "heavy write to > > > > irrelevant partition stalls the whole system". They are stuck on page > > > > allocation. Your 512MB system memory is a bit tight, so reclaim > > > > pressure is a bit high, which triggers the wait-on-writeback logic. > > > > > > I wonder if this hacking patch may help. > > > > > > When creating 300MB dirty file with dd, it is creating continuous > > > region of hard-to-reclaim pages in the LRU list. priority can easily > > > go low when irrelevant applications' direct reclaim run into these > > > regions.. > > > > Sorry I'm confused not. can you please tell us more detail explanation? > > Why did lumpy reclaim cause OOM? lumpy reclaim might cause > > direct reclaim slow down. but IIUC it's not cause OOM because OOM is > > only occur when priority-0 reclaim failure. > > No I'm not talking OOM. Nor lumpy reclaim. > > I mean the direct reclaim can get stuck for long time, when we do > wait_on_page_writeback() on lumpy_reclaim=1. > > > IO get stcking also prevent priority reach to 0. > > Sure. But we can wait for IO a bit later -- after scanning 1/64 LRU > (the below patch) instead of the current 1/1024. > > In Andreas' case, 512MB/1024 = 512KB, this is way too low comparing to > the 22MB writeback pages. There can easily be a continuous range of > 512KB dirty/writeback pages in the LRU, which will trigger the wait > logic. In my feeling from your explanation, we need auto adjustment mechanism instead change default value for special machine. no? -- 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