From owner-freebsd-hackers Thu Feb 27 11:31:23 2003 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B430137B401 for ; Thu, 27 Feb 2003 11:31:21 -0800 (PST) Received: from HAL9000.homeunix.com (12-233-57-224.client.attbi.com [12.233.57.224]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0F33D43FBF for ; Thu, 27 Feb 2003 11:31:21 -0800 (PST) (envelope-from das@FreeBSD.ORG) Received: from HAL9000.homeunix.com (localhost [127.0.0.1]) by HAL9000.homeunix.com (8.12.6/8.12.5) with ESMTP id h1RJVJ8Y038125; Thu, 27 Feb 2003 11:31:19 -0800 (PST) (envelope-from das@FreeBSD.ORG) Received: (from das@localhost) by HAL9000.homeunix.com (8.12.6/8.12.5/Submit) id h1RJVJFH038124; Thu, 27 Feb 2003 11:31:19 -0800 (PST) (envelope-from das@FreeBSD.ORG) Date: Thu, 27 Feb 2003 11:31:19 -0800 From: David Schultz To: Paul Robinson Cc: hiten@unixdaemons.com, hackers@FreeBSD.ORG Subject: Re: Disk scheduling in FreeBSD Message-ID: <20030227193119.GA37891@HAL9000.homeunix.com> Mail-Followup-To: Paul Robinson , hiten@unixdaemons.com, hackers@FreeBSD.ORG References: <1046361700.3e5e3664bcf24@webmail.unixdaemons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Thus spake Paul Robinson : > Hiten Pandya wrote: > > > Hello gang. > > > > Does anyone know what kind of `Disk Scheduling' algorithm, > > if any, is used in FreeBSD? > > I'm assuming you've read this recently then: > > http://www.kerneltrap.org/node-592.html ... > Anybody else got plans on this? I need to have a proper look around the > source tree, but I think this would be both self-contained (i.e. easy to > back out if it breaks) and useful. Quite a small-ish project really as well. The original anticipatory scheduler implementation was done for FreeBSD 4.3. See http://www.cs.rice.edu/~ssiyer/r/antsched/ I haven't looked carefully at it myself; I've only heard about it through someone who knows Margo Seltzer. It looks very interesting, although I worry that it would interfere with the prefetching and sequential heuristics that the VM system already does (which are already VERY good[1]). Maybe the authors already thought of that issue and addressed it. So in short, I don't know much about it, but I think it's worth looking into. [1] The fact that the improvement Linux got out of the new approach was so much greater than the improvement FreeBSD 4.3 got out of it is a testament to that fact, I think. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message