From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755313Ab0CIQTt (ORCPT ); Tue, 9 Mar 2010 11:19:49 -0500 Received: from hawking.rebel.net.au ([203.20.69.83]:55099 "EHLO hawking.rebel.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755122Ab0CIQTq (ORCPT ); Tue, 9 Mar 2010 11:19:46 -0500 Message-ID: <4B96751D.10804@davidnewall.com> Date: Wed, 10 Mar 2010 02:49:41 +1030 From: David Newall User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: jim owens CC: Christian Borntraeger , Jeff Garzik , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Akira Fujita Subject: Re: defrag deployment status (was Re: [PATCH] ext4: allow defrag (EXT4_IOC_MOVE_EXT) in 32bit compat mode) References: <201003072132.10579.borntraeger@de.ibm.com> <4B94367E.9080506@garzik.org> <201003080853.42978.borntraeger@de.ibm.com> <4B9518DA.8010201@davidnewall.com> <4B952437.8020607@gmail.com> In-Reply-To: <4B952437.8020607@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org jim owens wrote: > No. Your logic would be correct if rotating disks had > similar speed at all locations. Current disks are much > faster at the 0 end than at the middle or highest address. > I think my logic is still correct, although I wished I had said "closer to the middle." In fact, simplistic ideas for placement of files are unlikely to produce fabulous results (and that includes placing commonly used files towards the middle of the disk, say at the inside edge of the outermost zone.) The effort that BSD went to in FFS, placing directories with files and meta-data in cylinder groups, illustrates that disk performance is a sophisticated problem. Why don't we use BSD FFS/FFS2?