From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261521AbVFAXu6 (ORCPT ); Wed, 1 Jun 2005 19:50:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261512AbVFAXse (ORCPT ); Wed, 1 Jun 2005 19:48:34 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:44180 "EHLO e5.ny.us.ibm.com") by vger.kernel.org with ESMTP id S261520AbVFAXrj (ORCPT ); Wed, 1 Jun 2005 19:47:39 -0400 Date: Wed, 1 Jun 2005 16:47:30 -0700 From: Mike Kravetz To: Nick Piggin Cc: jschopp@austin.ibm.com, Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@osdl.org Subject: Re: Avoiding external fragmentation with a placement policy Version 12 Message-ID: <20050601234730.GF3998@w-mikek2.ibm.com> References: <20050531112048.D2511E57A@skynet.csn.ul.ie> <429E20B6.2000907@austin.ibm.com> <429E4023.2010308@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <429E4023.2010308@yahoo.com.au> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 02, 2005 at 09:09:23AM +1000, Nick Piggin wrote: > > It adds a lot of complexity to the page allocator and while > it might be very good, the only improvement we've been shown > yet is allocating lots of MAX_ORDER allocations I think? (ie. > not very useful) > Allocating lots of MAX_ORDER blocks can be very useful for things like hot-pluggable memory. I know that this may not be of interest to most. However, I've been combining Mel's defragmenting patch with the memory hotplug patch set. As a result, I've been able to go from 5GB down to 544MB of memory on my ppc64 system via offline operations. Note that ppc64 only employs a single (DMA) zone. So, page 'grouping' based on use is coming mainly from Mel's patch. -- Mike