From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755549AbXD0KIt (ORCPT ); Fri, 27 Apr 2007 06:08:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755528AbXD0KIt (ORCPT ); Fri, 27 Apr 2007 06:08:49 -0400 Received: from smtp110.mail.mud.yahoo.com ([209.191.85.220]:32597 "HELO smtp110.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755549AbXD0KIs (ORCPT ); Fri, 27 Apr 2007 06:08:48 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=th8M2P0H0Unq0V+gL0OBBWH014zd/XXwiOwLkXnN8Oto3S2PkEEXfpcLapSN56XBYLsi3PwPURrbdtJuapb/aQuTKB2u6DZF21a5h5P+urdOTVdtFyGWBvVsINXkB1exoztXsVlkVEyP2Eio2ZY1jmkK/XiI5I9BNrDJuVWjEFg= ; Message-ID: <4631CBA6.3090902@yahoo.com.au> Date: Fri, 27 Apr 2007 20:08:38 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Christoph Lameter CC: David Chinner , "Eric W. Biederman" , linux-kernel@vger.kernel.org, Mel Gorman , William Lee Irwin III , Jens Axboe , Badari Pulavarty , Maxim Levitsky Subject: Re: [00/17] Large Blocksize Support V3 References: <20070424222105.883597089@sgi.com> <46303A98.9000605@yahoo.com.au> <46304C74.9040304@yahoo.com.au> <20070426070454.GF32602149@melbourne.sgi.com> <46304FAF.7020700@yahoo.com.au> <46305222.60502@yahoo.com.au> <46305894.3050403@yahoo.com.au> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > On Thu, 26 Apr 2007, Nick Piggin wrote: > > >>Christoph Lameter wrote: >> >>>On Thu, 26 Apr 2007, Nick Piggin wrote: >>> >>> >>> >>>>But I maintain that the end result is better than the fragmentation >>>>based approach. A lot of people don't actually want a bigger page >>>>cache size, because they want efficient internal fragmentation as >>>>well, so your radix-tree based approach isn't really comparable. >>> >>> >>>Me? Radix tree based approach? That approach is in the kernel. Do not create >>>a solution where there is no problem. If we do not want to support large >>>blocksizes then lets be honest and say so instead of redefining what a block >>>is. The current approach is fine if one is satisfied with scatter gather and >>>the VM overhead coming with handling these pages. I fail to see what any of >>>what you are proposing would add to that. >> >>I'm not just making this up. Fragmentation. OK? > > > Yes you are. If you want to avoid fragmentation by restricting the OS to > 4k alone then the radix tree is sufficient to establish the order of pages > in a mapping. The only problem is to get an array of pointers to a > sequence of pages together by reading through the radix tree. I do not > know what else would be needed. No. We have avoided fragmentation up until now. We avoid fragmentation like the plague because it is crap. What _I_ do not want to do is add some patches that make it work a bit better and everyone think's that's a signal that it is a good idea to start using higher order allocations wherever possible. -- SUSE Labs, Novell Inc.