From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030358AbXDUI31 (ORCPT ); Sat, 21 Apr 2007 04:29:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030339AbXDUI31 (ORCPT ); Sat, 21 Apr 2007 04:29:27 -0400 Received: from smtp1.linux-foundation.org ([65.172.181.25]:58280 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030358AbXDUI30 (ORCPT ); Sat, 21 Apr 2007 04:29:26 -0400 Date: Sat, 21 Apr 2007 01:28:43 -0700 From: Andrew Morton To: Andy Whitcroft Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman Subject: Re: [PATCH 3/3] introduce HIGH_ORDER delineating easily reclaimable orders Message-Id: <20070421012843.f5a814eb.akpm@linux-foundation.org> In-Reply-To: References: 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 On Fri, 20 Apr 2007 16:04:36 +0100 Andy Whitcroft wrote: > The memory allocator treats lower order (order <= 3) and higher order > (order >= 4) allocations in slightly different ways. As lower orders > are much more likely to be available and also more likely to be > simply reclaimed it is deemed reasonable to wait longer for those. > Lumpy reclaim also changes behaviour at this same boundary, more > agressivly targetting pages in reclaim at higher order. > > This patch removes all these magical numbers and replaces with > with a constant HIGH_ORDER. oh, there we go. It would have been better to have patched page_alloc.c independently, then to have used HIGH_ORDER in "lumpy: increase pressure at the end of the inactive list". The name HIGH_ORDER is a bit squidgy. I'm not sure what would be better though. PAGE_ALLOC_CLUSTER_MAX? It'd be interesting to turn this into a runtime tunable, perhaps.