From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 26 Jan 2007 03:07:53 -0800 From: Andrew Morton 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter List-ID: 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, 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/ . Don't email: email@kvack.org