Re: DMA is not set automatically on my DVD-ROM drive in Debian?

I rarely used my Toshiba DVD-ROM Drive (hdc; IDE; SD-M1912/TMAG 16X/48X)
on my Debian/Linux box. This morning, I decided to copy about 600 MB of
files from a CD-R to a an IDE HDD (hda) that took almost ten minutes
long (based on my human clock). I believe that is too slow. Also, I
noticed my CPU was at the maximum which doesn't seem right.

I looked around and noticed something doesn't look right:
# /sbin/hdparm -v /dev/hdc

/dev/hdc:
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

My DVD-RW (Benq DW1650) has

hdparm /dev/hdc

/dev/hdc:
IO_support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 256 (on)
HDIO_GETGEO failed: Inappropriate ioctl for device

Hmm, 32-bit, enabled unmaskirq, etc. I wonder if those are the problems?


I don't know what HDIO_GETGEO failed: Inappropriate ioctl for device is
and don't know if that is a problem. The one I am concerned is the lack
of DMA. If I remember correctly (IIRC), DMA helps to speed up drives.
Maybe that is why my 600 MB copy files took forever.
[snip]

hdparm -tT /dev/xxx shows 850 + MB /s for buffer transfer for
both the hard drive and the DVD drive. Head transfer speed
is > 50MB/s for the HD, 6.19 MB/s for a DVD and 3.31 MB/s for
a CD.

It should take my system about 200 seconds to read a full CD.

Here's mine:

$ /sbin/hdparm -tT /dev/hdc

/dev/hdc:
Timing cached reads: 808 MB in 2.00 seconds = 403.62 MB/sec
BLKFLSBUF failed: Permission denied
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Permission denied
Timing buffered disk reads: 8 MB in 3.03 seconds = 2.64 MB/sec
BLKFLSBUF failed: Permission denied
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Permission denied

# /sbin/hdparm -tT /dev/hdc

/dev/hdc:
Timing cached reads: 868 MB in 2.00 seconds = 434.11 MB/sec
BLKFLSBUF failed: Function not implemented
Timing buffered disk reads: 10 MB in 4.03 seconds = 2.48 MB/sec
BLKFLSBUF failed: Function not implemented

# /sbin/hdparm -tT /dev/hda

/dev/hda:
Timing cached reads: 856 MB in 2.00 seconds = 428.03 MB/sec
Timing buffered disk reads: 164 MB in 3.03 seconds = 54.12 MB/sec


Just for kicks, I made a new CD-R copy of the same image because I
noticed the CD-R I used had some scratches. Maybe the scratches were
causing the slow downs. CPU were still high (1.xx -- load average:
1.31, 0.81, 0.40) and time was:

$ time cp -R /media/cdrom0/* .

real 4m9.138s
user 0m0.224s
sys 0m14.501s


I guess it was because of the scratches. OK, the questions is why no DMA
by default and why the high CPU usage? Or are those normal?

I forgot to mention that I have had this DVD-ROM drive since January
2005 and the motherboard since 9/2004. :)
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