From owner-cvs-sys  Wed Dec 11 06:24:03 1996
Return-Path: <owner-cvs-sys>
Received: (from root@localhost)
          by freefall.freebsd.org (8.8.4/8.8.4) id GAA12186
          for cvs-sys-outgoing; Wed, 11 Dec 1996 06:24:03 -0800 (PST)
Received: from dyson.iquest.net (dyson.iquest.net [198.70.144.127])
          by freefall.freebsd.org (8.8.4/8.8.4) with ESMTP id GAA12143;
          Wed, 11 Dec 1996 06:23:55 -0800 (PST)
Received: (from root@localhost) by dyson.iquest.net (8.8.2/8.6.9) id JAA03249; Wed, 11 Dec 1996 09:23:42 -0500 (EST)
From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199612111423.JAA03249@dyson.iquest.net>
Subject: Re: cvs commit: src/sys/ufs/ufs ufs_readwrite.c
To: bde@zeta.org.au (Bruce Evans)
Date: Wed, 11 Dec 1996 09:23:42 -0500 (EST)
Cc: jkh@time.cdrom.com, cvs-all@freefall.freebsd.org,
        CVS-committers@freefall.freebsd.org, cvs-sys@freefall.freebsd.org,
        dyson@freefall.freebsd.org
In-Reply-To: <199612110216.NAA27773@godzilla.zeta.org.au> from "Bruce Evans" at Dec 11, 96 01:16:28 pm
Reply-To: dyson@freebsd.org
X-Mailer: ELM [version 2.4 PL24 ME8]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-cvs-sys@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

> 
> There are a number of clones of the cmp and cp code in the tree.  E.g.,
> xinstall.c has a version of cmp with an arbitrary 8MB limit like cp.
> It's not clear that the mmap() version is faster than the read() version.
>
The mmap version has almost always recently been faster than read() when
the file is already cached.  Also, cp isn't nearly as bad as cmp when
actually reading from disk (due to the disk head contention that cmp
causes.)

John