From owner-freebsd-smp Fri Dec 8 12:56: 6 2000 From owner-freebsd-smp@FreeBSD.ORG Fri Dec 8 12:56:01 2000 Return-Path: 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 D0EB537B400; Fri, 8 Dec 2000 12:56:00 -0800 (PST) Received: (from daemon@localhost) by smtp02.primenet.com (8.9.3/8.9.3) id NAA10971; Fri, 8 Dec 2000 13:51:21 -0700 (MST) Received: from usr01.primenet.com(206.165.6.201) via SMTP by smtp02.primenet.com, id smtpdAAA3_aGsv; Fri Dec 8 13:51:10 2000 Received: (from tlambert@localhost) by usr01.primenet.com (8.8.5/8.8.5) id NAA22567; Fri, 8 Dec 2000 13:55:45 -0700 (MST) From: Terry Lambert Message-Id: <200012082055.NAA22567@usr01.primenet.com> Subject: Re: Netgraph and SMP To: msmith@FreeBSD.ORG (Mike Smith) Date: Fri, 8 Dec 2000 20:55:44 +0000 (GMT) Cc: smp@FreeBSD.ORG In-Reply-To: <200012080542.eB85gVN00523@mass.osd.bsdi.com> from "Mike Smith" at Dec 07, 2000 09:42:31 PM X-Mailer: ELM [version 2.5 PL2] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: tlambert@usr01.primenet.com Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > Er, what are you smoking Terry? You never 'update' the cache on another > > processor; the other processor snoops your cache/memory activity and > > invalidates its own cache based on your broadcasts. > > I should have added "if you're lucky" to this. Some platforms don't even > go that far. The BeBox is an example of a box without an L2 cachem and using the L2 cache control lines in order to implement MEI coherency for a maximum of two CPUs. You can actually get zero cycle bus arbitration to work with multiple MIPS processors (Phil Neiswanger initiated some work on this; I helped with the arbitration algorithm), also giving MEI coherency. I understand the limitations; please see my other posting. 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