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 083AE6B01F1 for ; Thu, 15 Apr 2010 00:09:05 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o3F493Tf028621 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 15 Apr 2010 13:09:03 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6E20A45DE57 for ; Thu, 15 Apr 2010 13:09:03 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 4548245DE4F for ; Thu, 15 Apr 2010 13:09:03 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 0875F1DB803A for ; Thu, 15 Apr 2010 13:09:03 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id AE6F21DB803C for ; Thu, 15 Apr 2010 13:09:02 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH] mm: disallow direct reclaim page writeback In-Reply-To: <20100415013436.GO2493@dastard> References: <20100414085132.GJ25756@csn.ul.ie> <20100415013436.GO2493@dastard> Message-Id: <20100415130212.D16E.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Date: Thu, 15 Apr 2010 13:09:01 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Dave Chinner Cc: kosaki.motohiro@jp.fujitsu.com, Mel Gorman , Chris Mason , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org List-ID: Hi > How about this? For now, we stop direct reclaim from doing writeback > only on order zero allocations, but allow it for higher order > allocations. That will prevent the majority of situations where > direct reclaim blows the stack and interferes with background > writeout, but won't cause lumpy reclaim to change behaviour. > This reduces the scope of impact and hence testing and validation > the needs to be done. Tend to agree. but I would proposed slightly different algorithm for avoind incorrect oom. for high order allocation allow to use lumpy reclaim and pageout() for both kswapd and direct reclaim for low order allocation - kswapd: always delegate io to flusher thread - direct reclaim: delegate io to flusher thread only if vm pressure is low This seems more safely. I mean Who want see incorrect oom regression? I've made some pathes for this. I'll post it as another mail. > Then we can work towards allowing lumpy reclaim to use background > threads as Chris suggested for doing specific writeback operations > to solve the remaining problems being seen. Does this seem like a > reasonable compromise and approach to dealing with the problem? Tend to agree. probably now we are discussing right approach. but this is definitely needed deep thinking. then, I can't take exactly answer yet. -- 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