From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 6 Dec 2001 08:51:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 6 Dec 2001 08:51:38 -0500 Received: from mplspop5.mpls.uswest.net ([204.147.80.2]:14347 "HELO mplspop5.mpls.uswest.net") by vger.kernel.org with SMTP id ; Thu, 6 Dec 2001 08:51:30 -0500 Date: Thu, 6 Dec 2001 07:51:26 -0600 Message-ID: <20011206075125.A23432@beaver.iucha.org> From: "Florin Iucha" To: "Alan Cox" Cc: "Florin Iucha" , linux-kernel@vger.kernel.org, faith@acm.org Subject: Re: Adaptec-2920 eats too much cpu time when reading from the CD-ROM In-Reply-To: <20011206030154.GA5979@iucha.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from alan@lxorguk.ukuu.org.uk on Thu, Dec 06, 2001 at 09:28:08AM +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 06, 2001 at 09:28:08AM +0000, Alan Cox wrote: > > I have recently purchased a Plextor 12x CD-RW and I have attached it to > > and Adaptec-2920 SCSI card. The card uses the "Future Domain Corp. TMC-18C30 > > [36C70]" chip. > > > > The problem I see: when reading from the CD-RW my system becomes very > > unresponsive and top reveals 90-95% of the time is spent on "system". > > My CPU is AMD K6-III/500MHz with 256 Mb RAM. > > I'd expect that. The 2920 is pretty old. It has no DMA channel and several > processes it must perform are polled not interrupt driven. There is one interesting thing about it: when I write a CD, I write at 12x - that means 1800Kb/s, which is comparable with the reading speed of 2400Kb/s. But when writing, the system CPU usage is about 30%. What could make the controller eat so much time when reading but not when writing? Thanks, florin PS. The patch fixes the "bad boy" message. -- "If it's not broken, let's fix it till it is." 41A9 2BDE 8E11 F1C5 87A6 03EE 34B3 E075 3B90 DFE4