From owner-freebsd-smp Mon Jun 28 18: 0:14 1999 Delivered-To: freebsd-smp@freebsd.org Received: from smtp04.primenet.com (smtp04.primenet.com [206.165.6.134]) by hub.freebsd.org (Postfix) with ESMTP id 8F43614D9C for ; Mon, 28 Jun 1999 18:00:12 -0700 (PDT) (envelope-from tlambert@usr05.primenet.com) Received: (from daemon@localhost) by smtp04.primenet.com (8.8.8/8.8.8) id RAA17445; Mon, 28 Jun 1999 17:58:05 -0700 (MST) Received: from usr05.primenet.com(206.165.6.205) via SMTP by smtp04.primenet.com, id smtpd017336; Mon Jun 28 17:57:52 1999 Received: (from tlambert@localhost) by usr05.primenet.com (8.8.5/8.8.5) id RAA07616; Mon, 28 Jun 1999 17:57:48 -0700 (MST) From: Terry Lambert Message-Id: <199906290057.RAA07616@usr05.primenet.com> Subject: Re: high-efficiency SMP locks - submission for review To: julian@whistle.com (Julian Elischer) Date: Tue, 29 Jun 1999 00:57:48 +0000 (GMT) Cc: dillon@apollo.backplane.com, peter@netplex.com.au, alc@cs.rice.edu, tlambert@primenet.com, bakul@torrentnet.com, freebsd-smp@freebsd.org In-Reply-To: from "Julian Elischer" at Jun 28, 99 09:16:44 am 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 > I'd say that we probably wouldn't support SMP on 386 and 486 processors.. > and in UP those locks that need atomicity would be optimised away. > > We WILL need locking in UP when we move to kernel threads, but that > doesn't require bus atomicity. No one is currently bothering with anything but the Intel MESI coherency model for SMP, anyway, so I don't understand the relevence of bus coherency to the argument. My only point is that the code needs to degrade gracefully (e.g. without rebuilding your kernel with a magic doohickey flipped on or off for no obvious reason). 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