Date: Thu, 12 Nov 1998 12:07:54 +1030 From: Greg Lehey <grog@lemis.com> To: Terry Lambert <tlambert@primenet.com>, "Justin T. Gibbs" <gibbs@narnia.plutotech.com> Cc: dillon@apollo.backplane.com, hackers@FreeBSD.ORG Subject: Re: SCSI tagged queueing and softupdates Message-ID: <19981112120754.E463@freebie.lemis.com> In-Reply-To: <199811110854.BAA07678@usr02.primenet.com>; from Terry Lambert on Wed, Nov 11, 1998 at 08:54:07AM %2B0000 References: <199811110257.TAA28938@narnia.plutotech.com> <199811110854.BAA07678@usr02.primenet.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?19981112120754.E463>