[mythtv-users] Random lockups on Mythbackend

Brian Wood beww at beww.org
Sun Dec 19 22:27:57 UTC 2010

On Sunday, December 19, 2010 02:40:21 pm dwoody1 wrote:
> Brian Wood wrote:
> > On Monday, December 13, 2010 12:51:23 pm dwoody1 wrote:
> >> On occasion the computer that has Mythbackend will lock up. This
> >> occurs once every couple of weeks and sometimes three or four
> >> times in a row. I have done a web search as well as looking
> >> through the archives of Mythtv and found nothing that comes close
> >> to the problem I am having. This leads me to believe that I have
> >> a setting that is completely inappropriate or I have a hardware
> >> problem, but this is the only failure that I have seen. I am
> >> running Fedora 13 with Mythtv .24 with all updates for both and 1
> >> Gig of memory. The following snippet from the Myth log file may
> >> point to a problem but I do not understand what it may be
> >> indicating. star9.home.com is the computer with Mythbackend.
> > 
> > You may have a hardware problem, as you say. Occasional hard locks
> > are often hardware related.
> > 
> > I'd run memtest for a couple of days to see if you have RAM
> > problems. PSU problems also can cause this type of symptom.
> Ran memtest86 for 65 hours. There were 137 passes with zero errors.
> > You might try running the machine without Myth to see is you have a
> > problem that's not related to Myth. Booting a Live CD of some
> > flavor is also a good way to test hardware. Many of them have
> > memtest built-in to them.
> > 
> > Re-seating all your cards and DIMMs can also help sometimes.
> I also did this.
> > I assume you also checked the system log for clues, as well as
> > Myth's log.
> This log had nothing to indicate any problems.
> Since the memtest ran for 64 hours and the computer normally runs for
> just a few, it would seem NOT to be a heat related problem.
> After the memtest I rebooted the computer and setup some shows to
> record (also set to run mythcommflag) while we watched some that had
> been recorded. I also started top from a remote login. After a short
> time the computer locked up. The lockup consist of a frozen video
> and about 1/4 second of audio played over and over again until I
> rebooted.
>  From the remote login, I noticed that top showed mythcommflag was
> using 169% CPU. The CPU is:
> AMD Athlon(tm) 64 X2 Dual Core Processor 4200+
> The motherboard is as Asus m2a-vm.
> Could it be that the computer is not powerful enough to handle a
> recording, mythcommflag job and a playback of a previous recorded
> show at the same time?

As always, it depends. Are we talking about SD or HD program material?

If it's SD, I'm sure you should be OK. I ran a machine with a single-
core AMD CPU that was slower than yours that handled 3 recordings, 2 
commflag jobs and a playback with software decoding  quite well.

(Recordings use very little CPU, unless you are doing software encoding, 
but commflag and software playback use a lot)

If you are talking about HD, that's another matter, especially if you 
are using software decoding.

Also, remember that memtest does not stress the CPU much at all, so you 
could have a thermal problem once you start to run something that uses a 
lot of CPU.

Are you monitoring your CPU temperature? How hot is it getting?

You might try turning off commercial flagging and see what happens.

Are you using the on-board Radeon video? If so, I'd seriously consider 
dropping a VDPAU-capable video card into the machine, software decoding 
of HD is very CPU intensive.

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