From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: [Bug 15884] cd-burning reduces other simultaneous IO performance Date: Fri, 30 Apr 2010 23:29:19 -0500 Message-ID: <4BDBAE1F.8090904@hardwarefreak.com> References: <201005010129.o411Tgn7022000@demeter.kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mo-65-41-216-221.sta.embarqhsd.net ([65.41.216.221]:33965 "EHLO greer.hardwarefreak.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750754Ab0EAE3V (ORCPT ); Sat, 1 May 2010 00:29:21 -0400 Received: from [192.168.100.53] (gffx.hardwarefreak.com [192.168.100.53]) by greer.hardwarefreak.com (Postfix) with ESMTP id 4B3816C306 for ; Fri, 30 Apr 2010 23:29:20 -0500 (CDT) In-Reply-To: <201005010129.o411Tgn7022000@demeter.kernel.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: linux-ide@vger.kernel.org bugzilla-daemon@bugzilla.kernel.org put forth on 4/30/2010 8:29 PM: > Now, there may be a difference in what commands the burning software is using > or the ordering that results in some of them taking longer than it does in > Windows or something. (I don't know the MMC commands that well but I think some > of them do have a mode where you can issue the command and poll periodically to > see if it's done rather than blocking on the operation until it finishes.) That > isn't anything the kernel can do anything about, though - if something issues a > command to one drive on the channel that takes a long time, anything wanting to > access the other drive just has to wait. This has been known for over a decade. When I was building white box Windows systems in the mid-late 90s our SOP was to put burners on a dedicated IDE port specifically due to what the OP reports over a decade later as a bug. As Robert points out above, this isn't a software bug, but a hardware limitation of IDE. Parallel SCSI, SAS, and SATA do not suffer this limitation. Apparently Windows engineers have developed a method over the years to mitigate the ill effects of this. I can tell you from experience that Windows 9x/ME/NT4/W2K all suffered performance degradation with HD+burner on the same channel problem. -- Stan