From owner-freebsd-current Mon Jul 12 10:40:56 1999 Delivered-To: freebsd-current@freebsd.org Received: from metriclient-2.uoregon.edu (metriclient-2.uoregon.edu [128.223.172.2]) by hub.freebsd.org (Postfix) with ESMTP id 71F6114DC3 for ; Mon, 12 Jul 1999 10:40:28 -0700 (PDT) (envelope-from gurney_j@efn.org) Received: (from jmg@localhost) by metriclient-2.uoregon.edu (8.9.1/8.8.7) id KAA00800; Mon, 12 Jul 1999 10:38:45 -0700 (PDT) Message-ID: <19990712103845.39296@hydrogen.fircrest.net> Date: Mon, 12 Jul 1999 10:38:45 -0700 From: John-Mark Gurney To: Matthew Dillon Cc: Luoqi Chen , dfr@nlsystems.com, jeremyp@gsmx07.alcatel.com.au, freebsd-current@FreeBSD.ORG, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") References: <199907121032.GAA14268@lor.watermarkgroup.com> <199907121647.JAA70249@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.69 In-Reply-To: <199907121647.JAA70249@apollo.backplane.com>; from Matthew Dillon on Mon, Jul 12, 1999 at 09:47:11AM -0700 Reply-To: John-Mark Gurney Organization: Cu Networking X-Operating-System: FreeBSD 3.0-RELEASE i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Matthew Dillon scribbled this message on Jul 12: > p.s. I'm pretty sure that the lock prefix costs nothing on a UP system, > and probably wouldn't be noticed on an SMP system either because the > write-allocation overhead is already pretty bad. But I haven't tested > it. actually, I'm not so sure, it guarantees that NO other bus operation will succeed while this is happening... what happens if a pci bus mastering card makes a modification to this value? sure, it normally won't happen, but it can... and w/o the lock prefix, this CAN happen from what I understand of the architecture... so, it does have to lock even the memory bus, simply the cache isn't enough for the lock to do what it needs... -- John-Mark Gurney Voice: +1 541 684 8449 Cu Networking P.O. Box 5693, 97405 "The soul contains in itself the event that shall presently befall it. The event is only the actualizing of its thought." -- Ralph Waldo Emerson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message