From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id DA5676B007D for ; Tue, 16 Feb 2010 02:03:49 -0500 (EST) Date: Tue, 16 Feb 2010 18:03:44 +1100 From: Nick Piggin Subject: Re: [patch 1/7 -mm] oom: filter tasks not sharing the same cpuset Message-ID: <20100216070344.GF5723@laptop> References: <20100215115154.727B.A69D9226@jp.fujitsu.com> <20100216110859.72C6.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100216110859.72C6.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: David Rientjes , Andrew Morton , Rik van Riel , KAMEZAWA Hiroyuki , Andrea Arcangeli , Balbir Singh , Lubos Lunak , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, Feb 16, 2010 at 01:52:02PM +0900, KOSAKI Motohiro wrote: > But this explanation is irrelevant and meaningless. CPUSET can change > restricted node dynamically. So, the tsk->mempolicy at oom time doesn't > represent the place of task's usage memory. plus, OOM_DISABLE can > always makes undesirable result. it's not special in this case. > > The fact is, both current and your heuristics have a corner case. it's > obvious. (I haven't seen corner caseless heuristics). then talking your > patch's merit doesn't help to merge the patch. The most important thing > is, we keep no regression. personally, I incline your one. but It doesn't > mean we can ignore its demerit. Yes we do need to explain the downside of the patch. It is a heuristic and we can't call either approach perfect. The fact is that even if 2 tasks are on completely disjoint memory policies and never _allocate_ from one another's nodes, you can still have one task pinning memory of the other task's node. Most shared and userspace-pinnable resources (pagecache, vfs caches and fds files sockes etc) are allocated by first-touch basically. I don't see much usage of cpusets and oom killer first hand in my experience, so I am happy to defer to others when it comes to heuristics. Just so long as we are all aware of the full story :) -- 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