From owner-freebsd-hackers Wed Nov 11 20:04:52 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id UAA19100 for freebsd-hackers-outgoing; Wed, 11 Nov 1998 20:04:52 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from narnia.plutotech.com (narnia.plutotech.com [206.168.67.130]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id UAA19093 for ; Wed, 11 Nov 1998 20:04:51 -0800 (PST) (envelope-from gibbs@narnia.plutotech.com) Received: (from gibbs@localhost) by narnia.plutotech.com (8.9.1/8.7.3) id UAA06570; Wed, 11 Nov 1998 20:57:37 -0700 (MST) Date: Wed, 11 Nov 1998 20:57:37 -0700 (MST) From: "Justin T. Gibbs" Message-Id: <199811120357.UAA06570@narnia.plutotech.com> To: Greg Lehey cc: hackers@FreeBSD.ORG Subject: Re: SCSI tagged queueing and softupdates X-Newsgroups: pluto.freebsd.hackers In-Reply-To: <199811110257.TAA28938@narnia.plutotech.com> <199811110854.BAA07678@usr02.primenet.com> <19981112120754.E463@freebie.lemis.com> User-Agent: tin/pre-1.4-980818 ("Laura") (UNIX) (FreeBSD/3.0-BETA (i386)) Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > 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. bowrite never does a synchronous write. Both the kernel elevator sort and the SCSI tagged queuing code honor the B_ORDERED flag, so even devices that cannot perform concurrent I/O can safely handled an ordered write in a non-blocking fashion. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message