From: Valdis.Kletnieks@vt.edu Subject: Re: defrag deployment status (was Re: [PATCH] ext4: allow defrag (EXT4_IOC_MOVE_EXT) in 32bit compat mode) Date: Mon, 08 Mar 2010 14:38:50 -0500 Message-ID: <4987.1268077130@localhost> 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> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1268077130_3874P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Cc: David Newall , Christian Borntraeger , Jeff Garzik , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Akira Fujita To: jim owens Return-path: Received: from lennier.cc.vt.edu ([198.82.162.213]:38353 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754245Ab0CHTjK (ORCPT ); Mon, 8 Mar 2010 14:39:10 -0500 In-Reply-To: Your message of "Mon, 08 Mar 2010 11:22:15 EST." <4B952437.8020607@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: --==_Exmh_1268077130_3874P Content-Type: text/plain; charset=us-ascii On Mon, 08 Mar 2010 11:22:15 EST, jim owens said: > 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. > > It is not unusual to see 2x difference in transfer speed > so you always want the important stuff as low as possible. On the flip side, seek time is so much larger than the time spent actually reading that minimizing the seeks will improve total throughput more. Sure, maybe you spend 0.05ms reading instead of 0.1ms - but if the seek took 0.75ms rather than 0.5ms you're still in the hole. --==_Exmh_1268077130_3874P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFLlVJKcC3lWbTT17ARAl4BAKCLFW+pPKSXPIIXdAUnL1t8FuJrwgCeO5pw Gz3e+Oqotdz2eyohbglpyg4= =vn5J -----END PGP SIGNATURE----- --==_Exmh_1268077130_3874P--