From owner-freebsd-stable@FreeBSD.ORG  Fri Feb  8 18:35:18 2008
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
Delivered-To: freebsd-stable@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id BB97216A469
	for <freebsd-stable@freebsd.org>; Fri,  8 Feb 2008 18:35:18 +0000 (UTC)
	(envelope-from kamikaze@bsdforen.de)
Received: from mail.bsdforen.de (bsdforen.de [212.204.60.79])
	by mx1.freebsd.org (Postfix) with ESMTP id 6D2B413C4D9
	for <freebsd-stable@freebsd.org>; Fri,  8 Feb 2008 18:35:18 +0000 (UTC)
	(envelope-from kamikaze@bsdforen.de)
Received: from mobileKamikaze.norad (nat-wh-1.rz.uni-karlsruhe.de
	[129.13.72.169])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(No client certificate requested)
	by mail.bsdforen.de (Postfix) with ESMTP id 02871405478;
	Fri,  8 Feb 2008 19:35:55 +0100 (CET)
Message-ID: <47ACA0E4.2030905@bsdforen.de>
Date: Fri, 08 Feb 2008 19:35:16 +0100
From: Dominic Fandrey <kamikaze@bsdforen.de>
User-Agent: Thunderbird 2.0.0.9 (X11/20080205)
MIME-Version: 1.0
To: Tom Evans <tevans.uk@googlemail.com>
References: <47A9F835.1060200@bsdforen.de>
	<47AA0696.5020109@bsdforen.de>	<7872AB6E-21DA-4E2D-93C0-D07CFA3A7E47@mac.com>	<47AA0E3E.4020304@bsdforen.de>	<e71790db0802071822l661bdcb8s6dfe5b94be11f0dc@mail.gmail.com>	<47ABF66E.4040807@bsdforen.de>	<e71790db0802080543g54d27bb8nfdc33e342f982b4@mail.gmail.com>	<1202485501.2126.34.camel@localhost>
	<47AC7FF6.1020801@bsdforen.de> <1202491071.2126.42.camel@localhost>
In-Reply-To: <1202491071.2126.42.camel@localhost>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: "Carlos A. M. dos Santos" <unixmania@gmail.com>, freebsd-stable@freebsd.org
Subject: Re: RELENG_7: interrupt eating whole cpu core
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>, 
	<mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
	<mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 08 Feb 2008 18:35:18 -0000

Tom Evans wrote:
> On Fri, 2008-02-08 at 17:14 +0100, Dominic Fandrey wrote:
>> Tom Evans wrote:
>>> If I try to turn on DMA, I just get WDMA2, which just doesn't cut it:
>> I think any DMA mode is fast enough to handle a DVD drive. There's just no 
>> necessity for more.
>>
> 
> WDMA is not UDMA. Any UDMA variant would be enough. WDMA2 provides a
> maximum of 16MiB/s, which will frequently lead to buffer underruns
> viewing a DVD. UDMA2 provides a maximum of 33MiB/s, which IS plenty.

16MB/s is exactly what is needed for 12x DVD access. I think this is the usual 
speed for a Notebook drive nowadays and it suffices for me.

>>>> # atacontrol mode acd0 udma5
>>> current mode = WDMA2
>> Same as for me. I'm satisfied with the speed of the drive.
> 
> I'm rarely satisfied - I'm quite often not bothered enough to pursue :)

Well, if 12x speed is not enough for you, you have to use an external drive. 
This is not a driver issue. It's just what your drive supports.