unkillable process in physrd-sttae

[Kevin Oberman]

> From: Mikhail Teterin <mi+mx at aldan.algebra.com>
> Date: Tue, 6 Jul 2004 13:46:55 -0400
> Sender: owner-freebsd-current at freebsd.org
> 
> => As I was playing a DVD, the picture stopped and everything seemingly
> => froze. I was able to login from another machine and look, what's
> => happening.
> =
> =I see this regularly, both DVD-Video playback and reading of files off
> =data DVD. Workaround is to list directories and read files from the DVD,
> =it will unstuck blocked process too. Or, issue 
> 
> I'm not so much concerned about the DVD-playback (`cdcontrol reset' is
> my workaround), but for the possibility of a process getting into a
> state, where it can not be killed. NFS-related issues used to be like
> this, but, it seems, `umount -f' works now.
> 
> =# atacontrol mode 1 udma33 xxx
> =
> =(in case your DVD unit is alone on secondary IDE channel)...
> 
> Thanks, I'll try that too. Currently I just run
> 
> 	while (1)
> 	cdcontrol reset
> 	sleep 1
> 	end
> 
> while the movie is playing :-(

I have seen similar problems on my ThinkPad T30. It used to work very
cleanly, but now I am getting intermittent freezes, too. My CD is also
running DMA33 with ATAPICAM and CURRENT updated at least once a week and
often much more frequently, but my windows (other than the on running
the application) don't freeze. I can't kill the process though and it
stays in the phyrd state.

I can simply run another application (in another window) that accesses
the DVD. As soon as I do that, the frozen window takes off again and
runs without any error.

This looks to me like I am losing an interrupt. The driver locks things
up until the new application kicks the drive, delivering an interrupt
and things are off and running.

I first noticed this about 2 weeks ago, but I had not used the drive for
a couple of months for large transfers, so I don;t know exactly when the
problem showed up. mplayer is the application I was using.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634