From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261282AbTDLW2b (for ); Sat, 12 Apr 2003 18:28:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261413AbTDLW2b (for ); Sat, 12 Apr 2003 18:28:31 -0400 Received: from ms-smtp-01.tampabay.rr.com ([65.32.1.43]:10461 "EHLO ms-smtp-01.tampabay.rr.com") by vger.kernel.org with ESMTP id S261282AbTDLW2a (for ); Sat, 12 Apr 2003 18:28:30 -0400 Message-ID: <001301c30145$5ff85fb0$6801a8c0@epimetheus> From: "Timothy Miller" To: Subject: Benefits from computing physical IDE disk geometry? Date: Sat, 12 Apr 2003 18:46:36 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2720.3000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I'm excited about the new I/O scheduler (proposed?) in the 2.5.x kernel, but I have to admit to a considerable amount of ignorance of its actual behavior. Thus, if it already does what I'm talking about, please feel free to ignore this post. :) Any good SCSI drive knows the physical geometry of the disk and can therefore optimally schedule reads and writes. Although necessary features, like read queueing, are also available in the current SATA spec, I'm not sure most drives will implement it, at least not very well. So, what if one were to write a program which would perform a bunch of seek-time tests to estimate an IDE disk's physical geometry? It could then make that information available to the kernel to use to reorder accesses more optimally. Additionally, discrepancies from expected seek times could be logged in the kernel and used to further improve efficiency over time. If it were good enough, many of the advantages of using SCSI disks would become less significant. Ideas?