[mythtv-users] Random lockups on Mythbackend

dwoody1 dwoody1 at charter.net
Mon Dec 20 03:46:45 UTC 2010

Brian Wood wrote:
> 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?

I record OTA and Mythtv shows 720, 1080, HD and sometimes blank. But, we 
live in Texas, so I assume it is all digital if that makes a difference.
> 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)

I have a pcHDTV 5500.

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

When I stopped play back of a 1080 show the cpu % dropped to the 70% 
range (still doing the other two jobs).

> 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?

When doing a recording, mythcommflag job and a playback of a previous 
recorded show at the same time the CPU % was normally 88% - 95% but it 
did spike to 98% - 99%. The temperature did go as high as 131 F. When 
the system crashed the cpu 0 was at 89%, CPU 1 was at 88% and the temp 
was at 129.2 F. The MB was at 98.6 F.

> 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.

I have been using the HDMI output. I thought that used less cpu than 
using VGA output. But perhaps still too much.

Could cpu usage between 88% - 95% be causing my problem?

If so, from your comments above, a VDPAU-capable video card would be 
called for. From your experience, are there cards that you would 
recommend or avoid?

Thanks again for your help,

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