From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx207.postini.com [74.125.245.207]) by kanga.kvack.org (Postfix) with SMTP id 3DD3D6B0069 for ; Thu, 5 Jan 2012 17:06:51 -0500 (EST) Date: Thu, 5 Jan 2012 14:06:45 -0800 From: Andrew Morton Subject: Re: [PATCH v5 7/8] mm: Only IPI CPUs to drain local pages if they exist Message-Id: <20120105140645.42498cdd.akpm@linux-foundation.org> In-Reply-To: <20120105161739.GD27881@csn.ul.ie> References: <1325499859-2262-1-git-send-email-gilad@benyossef.com> <1325499859-2262-8-git-send-email-gilad@benyossef.com> <4F033EC9.4050909@gmail.com> <20120105142017.GA27881@csn.ul.ie> <20120105144011.GU11810@n2100.arm.linux.org.uk> <20120105161739.GD27881@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Russell King - ARM Linux , KOSAKI Motohiro , Gilad Ben-Yossef , linux-kernel@vger.kernel.org, Chris Metcalf , Peter Zijlstra , Frederic Weisbecker , linux-mm@kvack.org, Pekka Enberg , Matt Mackall , Sasha Levin , Rik van Riel , Andi Kleen , Alexander Viro , linux-fsdevel@vger.kernel.org, Avi Kivity On Thu, 5 Jan 2012 16:17:39 +0000 Mel Gorman wrote: > mm: page allocator: Guard against CPUs going offline while draining per-cpu page lists > > While running a CPU hotplug stress test under memory pressure, I > saw cases where under enough stress the machine would halt although > it required a machine with 8 cores and plenty memory. I think the > problems may be related. When we first implemented them, the percpu pages in the page allocator were of really really marginal benefit. I didn't merge the patches at all for several cycles, and it was eventually a 49/51 decision. So I suggest that our approach to solving this particular problem should be to nuke the whole thing, then see if that caused any observeable problems. If it did, can we solve those problems by means other than bringing the dang things back? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org