From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965159AbVKPBvJ (ORCPT ); Tue, 15 Nov 2005 20:51:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965160AbVKPBvJ (ORCPT ); Tue, 15 Nov 2005 20:51:09 -0500 Received: from mx2.suse.de ([195.135.220.15]:60640 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S965159AbVKPBvH (ORCPT ); Tue, 15 Nov 2005 20:51:07 -0500 From: Andi Kleen To: Mel Gorman Subject: Re: [PATCH 2/5] Light Fragmentation Avoidance V20: 002_usemap Date: Wed, 16 Nov 2005 02:52:04 +0100 User-Agent: KMail/1.8.2 Cc: linux-mm@kvack.org, mingo@elte.hu, lhms-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, nickpiggin@yahoo.com.au References: <20051115164946.21980.2026.sendpatchset@skynet.csn.ul.ie> <200511160036.54461.ak@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200511160252.05494.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 16 November 2005 02:43, Mel Gorman wrote: > 1. I was using a page flag, valuable commodity, thought I would get kicked > for it. Usemap uses 1 bit per 2^(MAX_ORDER-1) pages. Page flags uses > 2^(MAX_ORDER-1) bits at worse case. Why does it need multiple bits? A page can only be in one order at a time, can't it? > 2. Fragmentation avoidance tended to break down, very fast. Why? The algorithm should the same, no? > 3. When changing a block of pages from one type to another, there was no > fast way to make sure all pages currently allocation would end up on > the correct free list If you can change the bitmap you can change as well mem_map -Andi