[MPlayer-users] Re: mplayer and preemptible kernel

[Anssi Saari]

On Tue, Oct 29, 2002 at 11:49:36PM +0100, Tobias Diedrich wrote:
> Nyk Tarr wrote:
> 
> > >From what I read on the linux kernel mailing list, ide-scsi does not
> > support dma. I suspect it never will as the only things that use it
> > (programs that need direct access to cd-rom/cd-rw etc. hardware) will
> > have a new interface to use in the next stable release. Oh, and the new
> > IDE code (>2.5.somethingorother) can have both ide-cd and ide-scsi
> > loaded for the same device.
> 
> Ok, I just did some short tests:
> 
> I have an IDE-DVDROM on /dev/hdd, I use ide-scsi and access this as
> /dev/scd0. I use kernel 2.4.19-ac4. By default DMA is enabled on all my
> IDE channels.
> If I put in a _data_ cdrom and do dd if=/dev/scd0 of=foo top shows ~9%
> system load. 
> After doing hdparm -d0 /dev/hdd this jumps to ~80% system load.
> 
> So I'd say it's very clear that DMA _does_ work with ide-scsi.
> 
> _However_ I know that it _does not_ work when _ripping audio_.

There's been a patch to enable DMA for audio ripping for a long time.

> But that is not different wether you use ide-scsi or not to access your
> CDROM.
> 
> -- 
> Tobias								PGP: 0x9AC7E0BC
> This mail is made of 100% recycled bits