Has anybody had any trouble with frames getting frozen every 1-2 seconds for a fraction of a second while playing DVDs? I have a 2.0G processor, 512M of RAM and 16x DVD drive. Since both players have the same problem, I was checking to see it was the CPU not being capable of decoding the frames, but the load never exceeded 50% at any point of time.

When I look at the dvd drive LED, it lights up exactly at the instant the frame freezes ( audio does not break at this point ) and it keeps on doing it every couple of seconds. What looks like the reason is a disk-read-wait here. Can I increase the 'read-buffer-size' or 'read-block-size' or something of the sort, so the software doesnt have to wait to get some more data from the drive before it can decode & render it?

Yeah i had the same problem. I turned on DMA for my DVD drive and it solved the problem.
man hdparm
hdparm -d 1 /dev/hdc
As root..
HTH
-NSKL

Thanks NSKL. DMA did it!!

Could you run hdparm -tT on your dvd drive and post it? My buffered disk reads seem to be on the slow side, so I want to compare it with someone else's to see if there's some tuning left to be done. Are you using UltraDMA?

/dev/dvd:
Timing buffer-cache reads: 128 MB in 0.54 seconds =237.04 MB/sec
Timing buffered disk reads: 64 MB in 17.72 seconds = 3.61 MB/sec

I also had the same problem. My problem now is that I can not get DMA to stay on after rebooting. How does one do that?

Adding the -k1 option to hdparm preserves state over 'soft' boots.

For Redhat, add
hdparm -d1 -k1 /dev/cdrom
line in /etc/rc.d/rc.local to preserve state over 'hard' boots.

--(Wed Oct 9, 21:48:21)--(root@SlackBox:/home/nskl)# hdparm -Tt /dev/dvd

/dev/dvd:
Timing buffer-cache reads: 128 MB in 0.52 seconds =246.15 MB/sec
Timing buffered disk reads: 64 MB in 22.48 seconds = 2.85 MB/sec

Slower than yours, still works fine tho...
-NSKL

well setting k in rc.local seems a bit bizarre seeing as the whole point of the k flag means you don't need to load them in rc.local.... the k flag stores it's settings in /etc/sysconfig/harddisks which is read by rc.sysinit on each boot, hard or soft.

unless i'm wrong that is...

I would like to see them stored somewhere, but dont know where. BTW, the following in an except from the hdparm man page

---------------------------------------------------------------------------

-k Get/set the keep_settings_over_reset flag for the drive. When this flag is set, the driver will preserve the -dmu options over a soft reset, (as done during the error recovery sequence). This flag defaults to off, to prevent drive reset loops which could be caused by combinations of -dmu settings. The -k flag should therefore only be set after one has achieved confidence in correct system operation with a chosen set of configuration settings. In practice, all that is typically necessary to test a configuration (prior to using -k) is to verify that the drive can be read/written, and that no error logs (kernel messages) are generated in the process (look in /var/adm/messages on most systems).

-K Set the drive's keep_features_over_reset flag. Setting this enables the drive to retain the settings for -APSWXZ over a soft reset (as done during the error recovery sequence). Not all drives support this feature.

------------------------------------------------------------------------

And my /etc/sysconfig/hardisks ( Redhat Stock ) is practically empty - all lines commented out. No trace of the changes I made to the DVD drive. Which makes me wonder if hdparm identifies my DVD drive as a non-fixed disk and treats in differently. Do you think?

Thanks again, NSKL.

whenever I run hdparm I get command not found. I have the man pages for it so I assume that I have it. What is the command in RH 8.0?
thanks for the help

look for /sbin/hdparm you're presuambly screwing up your path when you su to root. that's assuming you are root of course.

yeah, try
su -
That should execute /etc/profile inside the su shell and change the path to root's.

When I try to set the DMA of my dvd-rom by using hdpram -d 1 /dev/hdc I get the following message:

/dev/hdc:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)

Does anyone know how to fix this? Thanks in advance.

Have you tried this?

hdparm -d1 -k1 /dev/cdrom

What do you get?

Nevermind. I talked to some guy at Red Hat. He gave me a line to enter into etc/modules.conf. It's what you have to do to assign DMA in RH 8.0. The line for anyone curious is: options ide-cdrom dma=1