Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756702Ab0BPItW (ORCPT ); Tue, 16 Feb 2010 03:49:22 -0500 Received: from smtp-out.google.com ([216.239.33.17]:5782 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755909Ab0BPItU (ORCPT ); Tue, 16 Feb 2010 03:49:20 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=dVyHa8eY70lK1ogEAQHVqI5J1VlJM7HznCsKMKVZ9JyefBhNr0fmN4C2W7URCPiIC c6iqWaFEqDj1We+yqYeQA== Date: Tue, 16 Feb 2010 00:49:14 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Nick Piggin cc: KOSAKI Motohiro , Andrew Morton , Rik van Riel , KAMEZAWA Hiroyuki , Andrea Arcangeli , Balbir Singh , Lubos Lunak , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch 1/7 -mm] oom: filter tasks not sharing the same cpuset In-Reply-To: <20100216070344.GF5723@laptop> Message-ID: References: <20100215115154.727B.A69D9226@jp.fujitsu.com> <20100216110859.72C6.A69D9226@jp.fujitsu.com> <20100216070344.GF5723@laptop> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1480 Lines: 33 On Tue, 16 Feb 2010, Nick Piggin wrote: > 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 :) > Unless you can present a heuristic that will determine how much memory usage a given task has allocated on nodes in current's zonelist, we must exclude tasks from cpusets with a disjoint set of nodes, otherwise we cannot determine the optimal task to kill. There's a strong possibility that killing a task on a disjoint set of mems will never free memory for current, making it a needless kill. That's a much more serious consequence than not having the patch, in my opinion, than rather simply killing current. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/