[mythtv-users] Help debugging XvMC freezes

Misty P mistyp at thekorn.net
Wed Apr 23 20:15:13 UTC 2008


faginbagin wrote:
> I would rule out a software issue since you say killing and restarting
> mythfrontend fixes the problem.
>
> Make sure you can generate a core file, e.g. ulimit -c unlimited
>
> Start mythfrontend in a directory with lots of disk space and where
> you have write permission.
>
> When it locks up, kill the process with kill -segv
>
> Examine the core file using gdb. Do a stack trace of each thread.
> Commands of interest:
> info threads will list all the threads
> thread N will change the current thread to thread #N
> bt will produce stack trace of the thread
>
> If you see two or more threads in a pthread.*wait system call, then
> the problem is a thread deadlock, not a hardware problem. If so, a
> ticket might be in order, if you can document a reproducible scenario.

Thanks!  Upon a suggestion from the list, I was messing around with 
dramatically underclocking the card from its defaults, and *so far* it seems 
to have eliminated the freezes when using XvMC.

I'll keep this message around in case that turns out not to be the case long 
term, but *right now* it looks as though it's a case of an overly aggressive 
manufacturer clock rate on the card that is the culprit, rather than a 
software issue.  If nothing else, hopefully this will save future folks from 
scratching their head raw wondering why it doesn't work.




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