[mythtv] mythmusic/cdparanoia question (a little OT).

Matt Zimmerman mythtv-dev@snowman.net
Thu, 28 Nov 2002 11:07:05 -0500

On Thu, Nov 28, 2002 at 07:47:53AM -0800, Jim Radford wrote:

> On Wed, Nov 27, 2002 at 07:10:20PM -0500, Matt Zimmerman wrote:
> > On Thu, Nov 28, 2002 at 06:41:58PM +0000, Christian Morant wrote:
> > > I'm working on the ripping/encoding at the same time (and also adding cddb 
> > > info in the tables as well as other music refinments) but I would like to 
> > > know if you too have a cpu usage of 60 to 90 % while ripping an audio cd.
> > Welcome to the craptastic world of IDE.  I have a 40x IDE CD-ROM and a 32X
> > SCSI CD-RW in this machine.  While the IDE drive does CDDA slightly faster,
> > it uses about 1000% more CPU than the SCSI drive.
> Nope, that's just linux that's crappy (inspired by the initially
> crappy IDE cdroms) as it uses PIO instead of DMA when talking to the
> cdrom.  The newer 2.5 kernels don't have this problem thanks to Jens
> Axboe.
> Jens Axboe <axboe@suse.de> on Fri, 18 Oct 2002 writes:
> > This patch should make 2.5 ide-cd writing even faster than using
> > ide-scsi. Data is read/written directly to/from user space pages, and it
> > is done using dma whenever possible.

Here's a link to the actual message and patch for anyone who's interested:


This sounds great...but why do I see a similar (though less drastic)
difference between IDE and SCSI CPU utilization for hard disks, even when
DMA is enabled?

 - mdz