From owner-freebsd-hackers Tue Jan 26 12:07:15 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id MAA23002 for freebsd-hackers-outgoing; Tue, 26 Jan 1999 12:07:15 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from fledge.watson.org (FLEDGE.RES.CMU.EDU [128.2.93.229]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id MAA22994 for ; Tue, 26 Jan 1999 12:07:13 -0800 (PST) (envelope-from robert@cyrus.watson.org) Received: from fledge.watson.org (robert@fledge.pr.watson.org [192.0.2.3]) by fledge.watson.org (8.8.8/8.8.8) with SMTP id PAA28106; Tue, 26 Jan 1999 15:06:54 -0500 (EST) Date: Tue, 26 Jan 1999 15:06:54 -0500 (EST) From: Robert Watson X-Sender: robert@fledge.watson.org Reply-To: Robert Watson To: "Russell L. Carter" cc: hackers@FreeBSD.ORG Subject: Re: Error in vm_fault change In-Reply-To: <199901230616.XAA21124@psf.Pinyon.ORG> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 22 Jan 1999, Russell L. Carter wrote: > A single parameter like "priority" won't do it. Application > domains need scheduling partitions too. And there is no "GOD" algorithm > that fits all. I would suggest that if the scheduler needs to be reworked, > to fit at a minimum the kinds of work John lists, that people > think about how to provide a framework to plug in various scheduling > (process|memory) implementations. uhhhh, ye olde "strategy pattern". In Fall, 1997 someone here at CMU stuck a lottery algorithm scheduler into FreeBSD, and wrote a paper describing where they had to make changes to FreeBSD to allow for more pluggable schedulers. They didn't attempt to handle either real-time issues (and hence preemption for in-kernel processes) or SMP, but it might be a useful read. I'll see if I can dig up a reference. Allowing a pluggable scheduler via a kernel module would be pretty cool. I.e., today it's a realtime machine, tomorrow it's a single-user workstation, the next day a heavily loaded timesharing machine with CPU time partitioning. Robert N Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: 03 01 DD 8E 15 67 48 73 25 6D 10 FC EC 68 C1 1C Carnegie Mellon University http://www.cmu.edu/ TIS Labs at Network Associates, Inc. http://www.tis.com/ SafePort Network Services http://www.safeport.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message