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 ESMTP id F30A8600309 for ; Mon, 30 Nov 2009 18:09:50 -0500 (EST) Received: from zps38.corp.google.com (zps38.corp.google.com [172.25.146.38]) by smtp-out.google.com with ESMTP id nAUN9pgU008378 for ; Mon, 30 Nov 2009 15:09:51 -0800 Received: from pxi42 (pxi42.prod.google.com [10.243.27.42]) by zps38.corp.google.com with ESMTP id nAUN7fwg015847 for ; Mon, 30 Nov 2009 15:09:48 -0800 Received: by pxi42 with SMTP id 42so3201749pxi.5 for ; Mon, 30 Nov 2009 15:09:47 -0800 (PST) Date: Mon, 30 Nov 2009 15:09:44 -0800 (PST) From: David Rientjes Subject: Re: [PATCH] oom_kill: use rss value instead of vm size for badness In-Reply-To: <20091127182607.GA30235@random.random> Message-ID: References: <20091028175846.49a1d29c.kamezawa.hiroyu@jp.fujitsu.com> <20091029100042.973328d3.kamezawa.hiroyu@jp.fujitsu.com> <20091125124433.GB27615@random.random> <20091127182607.GA30235@random.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: KAMEZAWA Hiroyuki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , vedran.furac@gmail.com, KOSAKI Motohiro List-ID: On Fri, 27 Nov 2009, Andrea Arcangeli wrote: > Ok I can see the fact by being dynamic and less predictable worries > you. The "second to last" tasks especially are going to be less > predictable, but the memory hog would normally end up accounting for > most of the memory and this should increase the badness delta between > the offending tasks (or tasks) and the innocent stuff, so making it > more reliable. The innocent stuff should be more and more paged out > from ram. So I tend to think it'll be much less likely to kill an > innocent task this way (as demonstrated in practice by your > measurement too), but it's true there's no guarantee it'll always do > the right thing, because it's a heuristic anyway, but even total_vm > doesn't provide guarantee unless your workload is stationary and your > badness scores are fixed and no virtual memory is ever allocated by > any task in the system and no new task are spawned. > 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. -- 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