From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932307AbVJaF5i (ORCPT ); Mon, 31 Oct 2005 00:57:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932319AbVJaF5i (ORCPT ); Mon, 31 Oct 2005 00:57:38 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:55430 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S932317AbVJaF5h (ORCPT ); Mon, 31 Oct 2005 00:57:37 -0500 Date: Sun, 30 Oct 2005 21:57:25 -0800 From: Mike Kravetz To: Mel Gorman Cc: akpm@osdl.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, lhms-devel@lists.sourceforge.net Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <20051031055725.GA3820@w-mikek2.ibm.com> References: <20051030183354.22266.42795.sendpatchset@skynet.csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051030183354.22266.42795.sendpatchset@skynet.csn.ul.ie> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 30, 2005 at 06:33:55PM +0000, Mel Gorman wrote: > Here are a few brief reasons why this set of patches is useful; > > o Reduced fragmentation improves the chance a large order allocation succeeds > o General-purpose memory hotplug needs the page/memory groupings provided > o Reduces the number of badly-placed pages that page migration mechanism must > deal with. This also applies to any active page defragmentation mechanism. I can say that this patch set makes hotplug memory remove be of value on ppc64. My system has 6GB of memory and I would 'load it up' to the point where it would just start to swap and let it run for an hour. Without these patches, it was almost impossible to find a section that could be offlined. With the patches, I can consistently reduce memory to somewhere between 512MB and 1GB. Of course, results will vary based on workload. Also, this is most advantageous for memory hotlug on ppc64 due to relatively small section size (16MB) as compared to the page grouping size (8MB). A more general purpose solution is needed for memory hotplug support on architectures with larger section sizes. Just another data point, -- Mike