From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 21 Apr 2007 01:28:43 -0700 From: Andrew Morton Subject: Re: [PATCH 3/3] introduce HIGH_ORDER delineating easily reclaimable orders Message-Id: <20070421012843.f5a814eb.akpm@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andy Whitcroft Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman List-ID: 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. -- 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