From owner-freebsd-current Tue Sep 15 03:51:04 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id DAA08653 for freebsd-current-outgoing; Tue, 15 Sep 1998 03:51:04 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from isbalham.ist.co.uk (isbalham.ist.co.uk [192.31.26.1]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id DAA08644; Tue, 15 Sep 1998 03:50:55 -0700 (PDT) (envelope-from rb@gid.co.uk) Received: from gid.co.uk (uucp@localhost) by isbalham.ist.co.uk (8.8.7/8.8.7) with UUCP id LAA10118; Tue, 15 Sep 1998 11:50:35 +0100 (BST) (envelope-from rb@gid.co.uk) Received: from localhost by seagoon.gid.co.uk; Tue, 15 Sep 1998 11:44:57 +0100 (BST) Date: Tue, 15 Sep 1998 11:44:56 +0100 (BST) From: Bob Bishop X-Sender: rb@seagoon To: Terry Lambert cc: dg@root.com, joelh@gnu.org, tom@uniserve.com, gpalmer@FreeBSD.ORG, irc@cooltime.simplenet.com, freebsd-current@FreeBSD.ORG Subject: Re: Download of FreeBSD 3.0-SNAP In-Reply-To: <199809150156.SAA12652@usr05.primenet.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 15 Sep 1998, Terry Lambert wrote: > > FreeBSD's disksort function sorts by block number, not by cylinder number. > > Hence it being non-optimal; see Mike's post... optimial is "always does > exactly the right thing". It's not pessimal, either (as Mike pointed > out, too). What's "exactly the right thing" though? If you have two I/O limited processes trying to access opposite ends of the disk, you probably max out the throughput by preferring the transfer closest to where the heads currently are. This will almost certainly result in the 'unlucky' process getting I/O starved, which may not be acceptable. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message