From owner-cvs-src@FreeBSD.ORG  Sat Aug 30 03:04:12 2003
Return-Path: <owner-cvs-src@FreeBSD.ORG>
Delivered-To: cvs-src@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 6D04416A4BF; Sat, 30 Aug 2003 03:04:12 -0700 (PDT)
Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 3DC3043F85; Sat, 30 Aug 2003 03:04:10 -0700 (PDT)
	(envelope-from bde@zeta.org.au)
Received: from gamplex.bde.org (katana.zip.com.au [61.8.7.246])
	by mailman.zeta.org.au (8.9.3p2/8.8.7) with ESMTP id UAA28995;
	Sat, 30 Aug 2003 20:04:01 +1000
Date: Sat, 30 Aug 2003 20:04:00 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-X-Sender: bde@gamplex.bde.org
To: Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?= <des@des.no>
In-Reply-To: <xzpd6eocecg.fsf@dwp.des.no>
Message-ID: <20030830195022.D3440@gamplex.bde.org>
References: <200308220159.h7M1xTKi048687@repoman.freebsd.org>
 <xzpd6eocecg.fsf@dwp.des.no>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=X-UNKNOWN
Content-Transfer-Encoding: QUOTED-PRINTABLE
cc: cvs-src@FreeBSD.org
cc: src-committers@FreeBSD.org
cc: Warner Losh <imp@FreeBSD.org>
cc: cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/boot/i386/boot2 boot1.s
X-BeenThere: cvs-src@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: CVS commit messages for the src tree <cvs-src.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-src>
List-Post: <mailto:cvs-src@freebsd.org>
List-Help: <mailto:cvs-src-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-src>,
	<mailto:cvs-src-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 30 Aug 2003 10:04:12 -0000

On Sat, 30 Aug 2003, Dag-Erling [iso-8859-1] Sm=F8rgrav wrote:

> Warner Losh <imp@FreeBSD.org> writes:
> >   Log:
> >   Many newer CF do not handle having the entire track read from them at
> >   boot time.  Instead, read it a sector at a time.  While this sounds
> >   like a significant slowdown, I've not been able to measure any
> >   signficant difference.
>
> It should make a big difference on floppies.

Probably not even there for suitably modern hardware.  Try
"dd if=3D/dev/fd0 of=3D/dev/null".  It reads mostly as fast as possible, 1
sector at a time, although there is no track buffer in the driver.  It
only misses reading the next sector and has to wait for 1 revolution
after seeking, and naively implemented track reads would have the
same inefficiency.  I think all hardware newer than 8-10 years old
can keep up doing single-sector reads, at least with the FreeBSD
driver, but my BIOSes couldn't keep up in 1993 when I implemented
the track buffer in biosboot.

Bruce