CDROM/DVDROM drives on SATA IDE = no DMA
Brian Millett
bmillett at gmail.com
Thu May 25 14:43:39 UTC 2006
On Thu, 2006-05-25 at 09:14 -0300, Marcelo Magno T. Sales wrote:
> Hi,
>
> I have several desktop machines and notebooks which have CDROM / DVDROM
> connected to IDE SATA interfaces and they all have DMA disabled. Every time
> the CDROM/DVDROM drives are accessed, the computers slow down a lot and
> become almost unusable till it's finished. hdparm shows:
> [marcelo.sales at sf002698 ~]$ /sbin/hdparm /dev/dvd
>
> /dev/dvd:
> IO_support = 0 (default 16-bit)
> unmaskirq = 0 (off)
> using_dma = 0 (off)
> keepsettings = 0 (off)
> readonly = 0 (off)
> readahead = 256 (on)
> HDIO_GETGEO failed: Inappropriate ioctl for device
>
>
> When I try to enable DMA using hdparm, I get:
> [root at sf002698 ~]# hdparm -d1 /dev/dvd
>
> /dev/dvd:
> setting using_dma to 1 (on)
> HDIO_SET_DMA failed: Operation not permitted
> using_dma = 0 (off)
>
>
> Checking the config file for the stock kernel installed in these machines, I
> see:
> [marcelo.sales at sf002698 ~]$ grep _BLK_ /boot/config-$(uname -r) | grep SATA
> # CONFIG_BLK_DEV_IDE_SATA is not set
>
> I assume this is the reason why I can't turn on DMA, am I right? I believe
> many, many people shall suffer from this problem too. Should I open an RFE
> asking to enable this in the next kernel or is there a specific reason for
> not enabling this in the stock kernels? I hope I'll not need to recompile the
> kernel and install it in all these machines just because of this :)
Please do.
To get good performance I have to add the following to the boot kernel
parameters:
combined_mode=libata atapi_enabled=1
But the DMA is still not activated, however I can watch DVDs & burn
cd/dvds ok.
--
Brian Millett - [ G'Kar, "The War Prayer"]
"So much for Babylon 5's highly vaunted justice."
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