From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262597AbVFJQUP (ORCPT ); Fri, 10 Jun 2005 12:20:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262598AbVFJQUO (ORCPT ); Fri, 10 Jun 2005 12:20:14 -0400 Received: from graphe.net ([209.204.138.32]:48050 "EHLO graphe.net") by vger.kernel.org with ESMTP id S262597AbVFJQUK (ORCPT ); Fri, 10 Jun 2005 12:20:10 -0400 Date: Fri, 10 Jun 2005 09:20:00 -0700 (PDT) From: Christoph Lameter X-X-Sender: christoph@graphe.net To: "Martin J. Bligh" cc: Mel Gorman , Nick Piggin , jschopp@austin.ibm.com, linux-mm@kvack.org, lkml , Andrew Morton Subject: Re: Avoiding external fragmentation with a placement policy Version 12 In-Reply-To: <537960000.1118251081@[10.10.2.4]> Message-ID: References: <20050531112048.D2511E57A@skynet.csn.ul.ie> <429E20B6.2000907@austin.ibm.com><429E4023.2010308@yahoo.com.au> <423970000.1117668514@flay><429E483D.8010106@yahoo.com.au> <434510000.1117670555@flay><429E50B8.1060405@yahoo.com.au> <429F2B26.9070509@austin.ibm.com><1117770488.5084.25.camel@npiggin-nld.site> <370550000.1117807258@[10.10.2.4]> <537960000.1118251081@[10.10.2.4]> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Score: -5.9 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 8 Jun 2005, Martin J. Bligh wrote: > Right. I agree that large allocs should be reliable. Whether we care so > much about if they're performant or not, I don't know ... is an interesting > question. I think the answer is maybe not, within reason. The cost of > fishing in the allocator might well be irrelevant compared to the cost > of freeing the necessary memory area? Large consecutive page allocation is important for I/O. Lots of drivers are able to issue transfer requests spanning multiple pages which is only possible if the pages are in sequence. If memory is fragmented then this is no longer possible.