From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id ACDC96B003D for ; Tue, 1 Dec 2009 17:27:12 -0500 (EST) Received: from wpaz13.hot.corp.google.com (wpaz13.hot.corp.google.com [172.24.198.77]) by smtp-out.google.com with ESMTP id nB1MKHi6003901 for ; Tue, 1 Dec 2009 22:20:18 GMT Received: from pzk16 (pzk16.prod.google.com [10.243.19.144]) by wpaz13.hot.corp.google.com with ESMTP id nB1MJeSa012290 for ; Tue, 1 Dec 2009 14:20:14 -0800 Received: by pzk16 with SMTP id 16so3863163pzk.1 for ; Tue, 01 Dec 2009 14:20:12 -0800 (PST) Date: Tue, 1 Dec 2009 14:20:08 -0800 (PST) From: David Rientjes Subject: Re: [PATCH] oom_kill: use rss value instead of vm size for badness In-Reply-To: <20091201131509.5C19.A69D9226@jp.fujitsu.com> Message-ID: References: <20091127182607.GA30235@random.random> <20091201131509.5C19.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Andrea Arcangeli , KAMEZAWA Hiroyuki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , vedran.furac@gmail.com List-ID: On Tue, 1 Dec 2009, KOSAKI Motohiro wrote: > > The purpose of /proc/pid/oom_adj is not always to polarize the heuristic > > for the task it represents, it allows userspace to define when a task is > > rogue. Working with total_vm as a baseline, it is simple to use the > > interface to tune the heuristic to prefer a certain task over another when > > its memory consumption goes beyond what is expected. With this interface, > > I can easily define when an application should be oom killed because it is > > using far more memory than expected. I can also disable oom killing > > completely for it, if necessary. Unless you have a consistent baseline > > for all tasks, the adjustment wouldn't contextually make any sense. Using > > rss does not allow users to statically define when a task is rogue and is > > dependent on the current state of memory at the time of oom. > > > > I would support removing most of the other heuristics other than the > > baseline and the nodes intersection with mems_allowed to prefer tasks in > > the same cpuset, though, to make it easier to understand and tune. > > I feel you talked about oom_adj doesn't fit your use case. probably you need > /proc/{pid}/oom_priority new knob. oom adjustment doesn't fit you. > you need job severity based oom killing order. severity doesn't depend on any > hueristic. > server administrator should know job severity on his system. > That's the complete opposite of what I wrote above, we use oom_adj to define when a user application is considered "rogue," meaning that it is using far more memory than expected and so we want it killed. As you mentioned weeks ago, the kernel cannot identify a memory leaker; this is the user interface to allow the oom killer to identify a memory-hogging rogue task that will (probably) consume all system memory eventually. The way oom_adj is implemented, with a bit shift on a baseline of total_vm, it can also polarize the badness heuristic to kill an application based on priority by examining /proc/pid/oom_score, but that wasn't my concern in this case. Using rss as a baseline reduces my ability to tune oom_adj appropriately to identify those rogue tasks because it is highly dynamic depending on the state of the VM at the time of oom. -- 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