Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753558Ab0DOETj (ORCPT ); Thu, 15 Apr 2010 00:19:39 -0400 Received: from mga03.intel.com ([143.182.124.21]:57529 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972Ab0DOETi (ORCPT ); Thu, 15 Apr 2010 00:19:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,209,1270450800"; d="scan'208";a="265917459" Date: Thu, 15 Apr 2010 12:19:31 +0800 From: Wu Fengguang To: KOSAKI Motohiro Cc: Andreas Mohr , Jens Axboe , Minchan Kim , Linux Memory Management List , "linux-kernel@vger.kernel.org" , Rik van Riel Subject: Re: 32GB SSD on USB1.1 P3/700 == ___HELL___ (2.6.34-rc3) Message-ID: <20100415041931.GA14215@localhost> References: <20100407070050.GA10527@localhost> <20100407070842.GA18215@localhost> <20100415122928.D168.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100415122928.D168.A69D9226@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2549 Lines: 69 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. Thanks, Fengguang > > > > > > Thanks, > > Fengguang > > --- > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index e0e5f15..f7179cf 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1149,7 +1149,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, > > */ > > if (sc->order > PAGE_ALLOC_COSTLY_ORDER) > > lumpy_reclaim = 1; > > - else if (sc->order && priority < DEF_PRIORITY - 2) > > + else if (sc->order && priority < DEF_PRIORITY / 2) > > lumpy_reclaim = 1; > > > > pagevec_init(&pvec, 1); > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/