From owner-freebsd-hackers Wed Nov 11 19:56:00 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA18258 for freebsd-hackers-outgoing; Wed, 11 Nov 1998 19:53:57 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from papillon.lemis.com (freebie.lemis.com [139.130.136.133] (may be forged)) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id TAA18251 for ; Wed, 11 Nov 1998 19:53:52 -0800 (PST) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by papillon.lemis.com (8.9.1/8.6.12) with ESMTP id MAA00731; Thu, 12 Nov 1998 12:07:28 +1030 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.1/8.9.0) id MAA04011; Thu, 12 Nov 1998 12:07:54 +1030 (CST) Message-ID: <19981112120754.E463@freebie.lemis.com> Date: Thu, 12 Nov 1998 12:07:54 +1030 From: Greg Lehey To: Terry Lambert , "Justin T. Gibbs" Cc: dillon@apollo.backplane.com, hackers@FreeBSD.ORG Subject: Re: SCSI tagged queueing and softupdates References: <199811110257.TAA28938@narnia.plutotech.com> <199811110854.BAA07678@usr02.primenet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.91.1i In-Reply-To: <199811110854.BAA07678@usr02.primenet.com>; from Terry Lambert on Wed, Nov 11, 1998 at 08:54:07AM +0000 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wednesday, 11 November 1998 at 8:54:07 +0000, Terry Lambert wrote: >>> The SCSI command set allows you to flag >>> tags for ordered sequencing. >> >> Yes, but softupdates does not make use of this mechanism even though, >> via 'bowrite' it could. > > I agree on the value of this. But this seems to infringe on the > USL patent for "Delayed Ordered Writes". Details? It's been a while since the B_ORDERED flag (and bowrite) made the system: revision 1.33 date: 1996/09/06 05:35:00; author: gibbs; state: Exp; lines: +6 -4 Add B_ORDERED buffer flag and prototype for the bowrite function. Bowrite guarantees that buffers queued after a call to bowrite will be written after the specified buffer (to a particular device). Bowrite does this either by taking advantage of hardware ordering support (e.g. tagged queueing on SCSI devices) or by resorting to a synchronous write. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message