
Originally Posted by
Gianfranco
brunomcl ha scritto:
--
> Typically, your CD/DVD drive should use DMA to speed data transfer,
> bypassing the CPU. If DMA is disabled, the drive defaults to PIO mode,
> that, besides being slower, consumes a lot of CPU cycles. This makes the
> video jerky and increases CPU usage.
>
> The problem is that if a CD/DVD drive detects any throttling in the
> transfer process, it starts do downgrade the transfer method; from UDMA
> to DMA to PIO, and IT DOES NOT GO BACK TO UDMA by itself. The OS may try
> to set it back to UDMA at the next reboot, or not.
>
> Now, opensuse 10.3 and previous had a IDE DMA Mode settings in Yast's
> hardware module where you could check/set the DMA mode of your IDE
> drives, but for some reason this was removed from 11.0. So you have to
> resort to the command line utility hdparm. Type "man hdparm" without
> quotes at a terminal prompt to learn how it works. It's not difficult.
>
> Keep in mind, however, that a drive that constantly drops out of DMA
> mode has a problem. It may be itself, or the other drive it's
> transferring data to, or a defective data cable, etc. Modern computers
> should have absolutely no difficulty in reading a standard DVD - in mine
> (Athlon X2) the CPU usage is less than 15% for DVD playback with
> postprocessing turned on.
>
> Good luck.
>
>
Thank for the answer.
I used hdparm with "hdparm -d 1 /dev/sr0" but this don't was good for
a error
HDIO_SET_DMA failed: Inappropriate ioctl for device
HDIO_GET_DMA failed: Inappropriate ioctl for device
and I don't know what to do to set.
I don't understand why "pata_ali.atapi_dma=1" in the boot options work.
DVD playback on openSUSE 10.3 and Xp is fine.
Thank again and Bye.
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