[mythtv-users] Could realtime commercial flagging cause hard lockup/freeze/hang?

Greg Grotsky spikeygg at gmail.com
Wed Jun 4 13:49:16 UTC 2008

On Tue, Jun 3, 2008 at 10:10 PM, Brian Foddy <bfoddy at visi.com> wrote:

>  I'd guess its some kernel deadlock with a device driver.  What tuner card
> is (are) running during the process.  If the machine is really busy, and
> you have some of the kernel preempt settings on, and there is a bug
> in the driver, it could cause a hard crash.

I am using a pchdtv HD-3000 tuner using DVB.  If that was the case should it
spit something out in the syslog?  Maybe there's a setting somewhere I can
flip to increase verbosity when logging...?

> What type of computer?  Multi-core, dual CPU?  Using SMP kernel?
> These can cause driver bugs more readily.  If its an SMP instance,
> try your test with SMP disabled (there is a kernel param that will do
> this).

It's an AMD X2 4200+ cpu, with SMP enabled in the kernel.  I'm using a
custom built kernel so I'd have to recompile it without SMP enabled but
that's something to try, it has been working fine for at least a year with
this processor.  I previously had a AMD 3200+ single core and it worked for
like three years with this processor.

> The commercial scan itself is probably (haven't looked at code, but
> I can't imagine) doing anything other than standard file I/O using
> normal calls, so root or not, I don't see it the problem.  But if it
> keeps the system busy, it could cause other faults to show up.
> In general, hard lock ups / crashes are due to faulty / buggy device
> drivers
> or hardware failures.

Yeah, your arguement seems sound.  So far the machine has been running for
2.5 days without a crash after removing the "start commercial detection as
soon as recording starts" option.  Maybe it is just that I'm spreading out
the file I/O calls so they aren't on top of one another.
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