Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932838AbXAZLIO (ORCPT ); Fri, 26 Jan 2007 06:08:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932886AbXAZLIO (ORCPT ); Fri, 26 Jan 2007 06:08:14 -0500 Received: from smtp.osdl.org ([65.172.181.24]:56040 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932838AbXAZLIN (ORCPT ); Fri, 26 Jan 2007 06:08:13 -0500 Date: Fri, 26 Jan 2007 03:07:53 -0800 From: Andrew Morton To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter Subject: Re: [PATCH 0/8] Create ZONE_MOVABLE to partition memory between movable and non-movable pages Message-Id: <20070126030753.03529e7a.akpm@osdl.org> In-Reply-To: <20070125234458.28809.5412.sendpatchset@skynet.skynet.ie> References: <20070125234458.28809.5412.sendpatchset@skynet.skynet.ie> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 43 On Thu, 25 Jan 2007 23:44:58 +0000 (GMT) Mel Gorman wrote: > The following 8 patches against 2.6.20-rc4-mm1 create a zone called > ZONE_MOVABLE Argh. These surely get all tangled up with the make-zones-optional-by-adding-zillions-of-ifdef patches: deal-with-cases-of-zone_dma-meaning-the-first-zone.patch introduce-config_zone_dma.patch optional-zone_dma-in-the-vm.patch optional-zone_dma-in-the-vm-no-gfp_dma-check-in-the-slab-if-no-config_zone_dma-is-set.patch optional-zone_dma-in-the-vm-no-gfp_dma-check-in-the-slab-if-no-config_zone_dma-is-set-reduce-config_zone_dma-ifdefs.patch optional-zone_dma-for-ia64.patch remove-zone_dma-remains-from-parisc.patch remove-zone_dma-remains-from-sh-sh64.patch set-config_zone_dma-for-arches-with-generic_isa_dma.patch zoneid-fix-up-calculations-for-zoneid_pgshift.patch My objections to those patches: - They add zillions of ifdefs - They make the VM's behaviour diverge between different platforms and between differen configs on the same platforms, and hence degrade maintainability and increase complexity. - We kicked around some quite different ways of implementing the same things, but nothing came of it. iirc, one was to remove the hard-coded zones altogether and rework all the MM to operate in terms of for (idx = 0; idx < NUMBER_OF_ZONES; idx++) ... - I haven't seen any hard numbers to justify the change. So I want to drop them all. - 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/