[mythtv-users] Problems with multiple pvr cards

Brian L. Walter blwalter at gmail.com
Wed May 9 10:24:16 UTC 2007


Karl E. Jorgensen wrote:
> On Tue, May 08, 2007 at 08:31:28PM -0400, Brian L. Walter wrote:
>   
>> Greetings,
>>
>> I've got 1 pvr-500 and one pvr-150, running ivtv 0.10.1 with myth 
>> 0.20-fixes as of 5/6.
>>
>> I have run a couple 30 minute cat /dev/videoN against all 3 devices 
>> simultaneously, with no problem.
>>     
>
> Was this a simple "cat /dev/videoN > /dev/null" or did the output go to
> disk?
>
>   
>> However, when Myth goes to record on all 3, I start getting ENC DMA 
>> Errors, anywhere from  immediately to 20-30 minutes.
>>     
>
> Obviously, myth writes to disk :-)
>
>   
>> I've read that there is an interrupt issue with the 0.10.1, and was
>> wondering if this is a result of that issue.
>>     
>
> Could be. But you need to take the total load of the box into account -
> so myth's disk activity may become significant.
>
>   
>> This problem does not occur when only 2 of the three inputs are in
>> use, only with all three.  The only way to clear it up is to reboot,
>> because this situation will eventually lead to dma timeouts, and
>> driver not responding....then...system crash.
>>     
>
> Yuck.
>
> If your tests before did not write to disk, try some that do. If the
> to-disk tests produce DMA errors whereas the not-to-disk ones do not,
> then the disk activity is significant (but not necessarily the cause).
> Then it would be time to try things bonnie++ (without touching the PVRs)
> to elimiate disk DMA problems...
>
> Hope this helps
>
>   
For what it's worth - one additional tidbit.  If I run the cat test on a 
newly rebooted machine, it works.  If myth has touched the tunners, 
then, I get the failure.  I'm really thinking it's something in the 
recording profile....?


Brian


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