[mythtv-users] Problems with multiple pvr cards

[Brian L. Walter]

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
>
>   
Thanks for the tips. 

The cat's where to disk...so it's as close (I hipe) to mimicking what 
myth does without using myth.

I was beginning to think disk - and latency.  However, it appears you 
can't change the latency on this motherboard (or least, not without 
calling Asus support - guess I'll have to sit in the queue for a bit :) ).

Do people have 'recomended' settings for the  PVR's in terms of 
recording profiles?  Again, I saw something on the IVTV site that 
implied that resolution needs to be 720x480...and was wondering if the 
bit rates figure into this too...

TIA
Brian