From owner-freebsd-smp Mon Jun 28 17:55:51 1999 Delivered-To: freebsd-smp@freebsd.org Received: from smtp02.primenet.com (smtp02.primenet.com [206.165.6.132]) by hub.freebsd.org (Postfix) with ESMTP id 575A314D9C for ; Mon, 28 Jun 1999 17:55:48 -0700 (PDT) (envelope-from tlambert@usr05.primenet.com) Received: (from daemon@localhost) by smtp02.primenet.com (8.8.8/8.8.8) id RAA28478; Mon, 28 Jun 1999 17:55:47 -0700 (MST) Received: from usr05.primenet.com(206.165.6.205) via SMTP by smtp02.primenet.com, id smtpd028376; Mon Jun 28 17:55:38 1999 Received: (from tlambert@localhost) by usr05.primenet.com (8.8.5/8.8.5) id RAA07451; Mon, 28 Jun 1999 17:55:25 -0700 (MST) From: Terry Lambert Message-Id: <199906290055.RAA07451@usr05.primenet.com> Subject: Re: high-efficiency SMP locks - submission for review To: dillon@apollo.backplane.com (Matthew Dillon) Date: Tue, 29 Jun 1999 00:55:25 +0000 (GMT) Cc: jhay@mikom.csir.co.za, peter@netplex.com.au, alc@cs.rice.edu, tlambert@primenet.com, bakul@torrentnet.com, julian@whistle.com, freebsd-smp@FreeBSD.ORG In-Reply-To: <199906281947.MAA24287@apollo.backplane.com> from "Matthew Dillon" at Jun 28, 99 12:47:25 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > Since 386's are UP systems, I think it would be fairly easy to implement > the UP version of the compare-and-exchange primitive trivially with an > spl wrapper. We should be able to freely use use the cmpxchg instruction > on SMP systems. Unless this was done at runtime, ala the bcopy code, I think that it would be a terrible idea to balkanize the systems that a generic kernel was capable of running on without recompilation. I think the locking mechanics for SMP are just as applicable to kernel preemption (aka one process Real Time or multiprocess "mushy" Real Time), and that that avenue should not be cut off for older systems. This is doubly true for older systems, in fact, which have a much higher tendency to show up in embedded controllers and other applications that require some small RT capability, than, say, 450MHz Xeon processors. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message