From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 52E786B00A3 for ; Sun, 24 Oct 2010 23:53:52 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o9P3rmv5028702 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Mon, 25 Oct 2010 12:53:49 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 16D5945DE7B for ; Mon, 25 Oct 2010 12:53:46 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 31BE545DE70 for ; Mon, 25 Oct 2010 12:53:45 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id D36A51DB8037 for ; Mon, 25 Oct 2010 12:53:44 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9A5A81DB803A for ; Mon, 25 Oct 2010 12:53:43 +0900 (JST) Date: Mon, 25 Oct 2010 12:48:16 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] do_migrate_range: avoid failure as much as possible Message-Id: <20101025124816.330846a5.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20101025034833.GB15933@localhost> References: <1287974851-4064-1-git-send-email-lliubbo@gmail.com> <20101025114017.86ee5e54.kamezawa.hiroyu@jp.fujitsu.com> <20101025025703.GA13858@localhost> <20101025120550.45745c3d.kamezawa.hiroyu@jp.fujitsu.com> <20101025120901.88fdbd17.kamezawa.hiroyu@jp.fujitsu.com> <20101025034833.GB15933@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: Bob Liu , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "mel@csn.ul.ie" , "kosaki.motohiro@jp.fujitsu.com" List-ID: On Mon, 25 Oct 2010 11:48:33 +0800 Wu Fengguang wrote: > On Mon, Oct 25, 2010 at 11:09:01AM +0800, KAMEZAWA Hiroyuki wrote: > > On Mon, 25 Oct 2010 12:05:50 +0900 > > KAMEZAWA Hiroyuki wrote: > > > > > This changes behavior. > > > > > > This "ret" can be > 0 because migrate_page()'s return code is > > > "Return: Number of pages not migrated or error code." > > > > > > Then, > > > ret < 0 ===> maybe ebusy > > > ret > 0 ===> some pages are not migrated. maybe PG_writeback or some > > > ret == 0 ===> ok, all condition green. try next chunk soon. > > > > > > Then, I added "yield()" and --retrym_max for !ret cases. > > ^^^^^^^^ > > wrong. > > > > The code here does > > > > ret == 0 ==> ok, all condition green, try next chunk. > > It seems reasonable to remove the drain operations for "ret == 0" > case. That would help large NUMA boxes noticeably I guess. > Maybe. > > ret > 0 ==> all pages are isolated but some pages cannot be migrated. maybe under I/O > > do yield. > > Don't know how to deal with the possible "migration fail" pages -- > sorry I have no idea about that situation at all. > In typical case, page_count() > 0 by get_user_pages() or PG_writeback is set. All we can do is just waiting. > Perhaps, OOM while offlining pages? > I never see that..because memory offline is scheduled to be done only when there are free memory. Thanks, -Kame -- 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