From owner-freebsd-hackers Mon Nov 8 0:23:49 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from funkthat.com (adsl-63-195-54-213.dsl.snfc21.pacbell.net [63.195.54.213]) by hub.freebsd.org (Postfix) with ESMTP id 797821518E for ; Mon, 8 Nov 1999 00:23:46 -0800 (PST) (envelope-from gurney_j@efn.org) Received: (from jmg@localhost) by funkthat.com (8.9.1/8.8.7) id AAA13574; Mon, 8 Nov 1999 00:23:29 -0800 (PST) Message-ID: <19991108002329.24851@hydrogen.fircrest.net> Date: Mon, 8 Nov 1999 00:23:29 -0800 From: John-Mark Gurney To: Matthew Dillon Cc: FreeBSD Hackers Subject: Re: writing much slower than reading... References: <19991106013045.13836@hydrogen.fircrest.net> <199911080631.WAA89627@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.69 In-Reply-To: <199911080631.WAA89627@apollo.backplane.com>; from Matthew Dillon on Sun, Nov 07, 1999 at 10:31:57PM -0800 Reply-To: John-Mark Gurney Organization: Cu Networking X-Operating-System: FreeBSD 3.0-RELEASE i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Matthew Dillon scribbled this message on Nov 7: > When you write to a raw disk with your dd, it is reading a block from > /dev/zero into its local buffer which involves a zeroing operation > that the read code never had to do, then dd writes the buffer to disk. thank you! this is exactly what I was looking for... :) I wrote a simple test program that uses a static buffer of 1meg to read and write from... I ran the test to transfer 512megs and their system time is almost equal... I knew it was something really stupid like that... now to find out why the bt848 card can't sustain more than 15fps when I'm writing to the disk... and only can do 7-8fps in 640x480... probably something to do w/ the pci bus getting overloaded or the chipset... -- John-Mark Gurney Voice: +1 408 975 9651 Cu Networking "The soul contains in itself the event that shall presently befall it. The event is only the actualizing of its thought." -- Ralph Waldo Emerson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message