From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id AE2316B0044 for ; Tue, 3 Nov 2009 19:24:51 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id nA40OnBb001918 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Wed, 4 Nov 2009 09:24:49 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 28F0345DE5D for ; Wed, 4 Nov 2009 09:24:49 +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 0893645DE57 for ; Wed, 4 Nov 2009 09:24:49 +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 E49A11DB803C for ; Wed, 4 Nov 2009 09:24:48 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 97E3E1DB8038 for ; Wed, 4 Nov 2009 09:24:48 +0900 (JST) Date: Wed, 4 Nov 2009 09:22:13 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC][-mm][PATCH 3/6] oom-killer: count lowmem rss Message-Id: <20091104092213.02f27075.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20091102162244.9425e49b.kamezawa.hiroyu@jp.fujitsu.com> <20091102162617.9d07e05f.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, KOSAKI Motohiro , Andrea Arcangeli , Andrew Morton , minchan.kim@gmail.com, vedran.furac@gmail.com, Hugh Dickins List-ID: On Tue, 3 Nov 2009 12:24:01 -0800 (PST) David Rientjes wrote: > On Mon, 2 Nov 2009, KAMEZAWA Hiroyuki wrote: > > > From: KAMEZAWA Hiroyuki > > > > Count lowmem rss per mm_struct. Lowmem here means... > > > > for NUMA, pages in a zone < policy_zone. > > for HIGHMEM x86, pages in NORMAL zone. > > for others, all pages are lowmem. > > > > Now, lower_zone_protection[] works very well for protecting lowmem but > > possiblity of lowmem-oom is not 0 even if under good protection in the kernel. > > (As fact, it's can be configured by sysctl. When we keep it high, there > > will be tons of not-for-use memory but system will be protected against > > rare event of lowmem-oom.) > > Right, lowmem isn't addressed currently by the oom killer. Adding this > constraint will probably make the heuristics much harder to write and > understand. It's not always clear that we want to kill a task using > lowmem just because another task needs some, for instance. The same can be said against all oom-kill ;) > Do you think we'll need a way to defer killing any task is no task is > heuristically found to be hogging lowmem? Yes, I think so. But my position is a bit different. In typical x86-32 server case, which has 4-8G memory, most of memory usage is highmem. So, if we have no knowledge of lowmem, multiple innocent processes will be killed in every 30 secs of oom-kill. My final goal is migrating lowmem pages to highmem as kswapd-migraion or oom-migration. Total rewrite for this will be required in future. Thanks, -Kame Thanks, -Kame 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