From: David Newall Subject: Re: defrag deployment status (was Re: [PATCH] ext4: allow defrag (EXT4_IOC_MOVE_EXT) in 32bit compat mode) Date: Tue, 09 Mar 2010 02:03:46 +1030 Message-ID: <4B9518DA.8010201@davidnewall.com> References: <201003072132.10579.borntraeger@de.ibm.com> <4B94367E.9080506@garzik.org> <201003080853.42978.borntraeger@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jeff Garzik , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Akira Fujita To: Christian Borntraeger Return-path: In-Reply-To: <201003080853.42978.borntraeger@de.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Christian Borntraeger wrote: > Some bigger things are missing in the e4defrag tool: > ... > - overall layout considerations (e.g. putting files close to its directory or > use the atime to move often used files to the beginning of a disk etc.) Shouldn't oft-used files be placed closer to the middle? If you place them at the beginning of the file, it's only possible for the head-stack to be close to the file from the inner direction. Place them in the middle and it's possible for the head-stack to be close from the outer direction, too, which sounds like a doubling of probability. It seems that it's the least frequently used files that should be placed at one end of the disk or the other.