[mythtv-users] Where does commercial flagging happen???

[Brian Wood]

James Crow wrote:
> On Tue, 2008-11-04 at 10:02 -0700, Brian Wood wrote:
>> stuart wrote:
>>> Hi...
>>>
>>> I had noticed that when my single core MBE was commercial flagging that 
>>> the duel core SBE would not be able to play back programming streamming 
>>> from the MBE w/o some annoying jitter.  So I disabled the commercial 
>>> flagging on the MBE unless it was between midnight and 6am.  (Solving 
>>> this problem, if possible, deserves another thread.)
>>>
>>> Recently, I noticed the duel core SBE was again having jitter problems. 
>>>   This time playing as SD OTA ATSC recording.  Hummmm!  I checked and 
>>> noticed the SBE was doing a commercial flagging session.  I'm thinking 
>>> this shouldn't be a problem - it's a duel core machine!
>>>
>>> Then a friend suggested the SBE was doing a MBE commercial flagging. 
>>> That is, I was probably transmitting the equivalent of 3 shows over my 1 
>>> network between the MBE and SBE machines.
>>>
>>> Even if I didn't set the "flag commercials on the machine it was 
>>> recorded on" for either the MBE or SBE, I would have never thought a 
>>> mythtv network would go out of it's way to flag commercials on anything 
>>> but the MBE.
>>>
>>> So what to people think, will setting the MBE to only flag commercials 
>>> during off hours (something like midnight to 6am) cause the MBE to 
>>> executed a "remote commercial flagging session" on a recording recorded 
>>> and stored on the MBE?
>>>
>>> (Note, FYI, there are tuners on both the MBE and SBE machines.)
>> The problem may well not be CPU resources, but disk I/O. Many people
>> have pointed out that it's best to have your OS and/or DB on a different
>> spindle from the video storage.
>>
>> I had a similar problem on an older machine, which was solved by
>> adjusting the PCI latency values of the IDE controllers.
>>
>> I was then able to make 3 recordings, run a commflag job and playback a
>> recording, all at the same time (all SD) with a single-core AMD64 3700+
>> (running in 32-bit mode).
>>
>> I'd look at your disk I/O situation when flagging commercials while
>> playing back.
>>
>>
>> bew
> 
> Brian,
> 
>   Would you mind sharing any hints on how to monitor disk i/o or change
> PCI latency under Linux? I think I may be hitting this issue while
> recording three streams (PVR-500, OTA ATSC), comm flagging and watching
> a HD show.

Check out:

http://www.mythtv.org/wiki/index.php/PCI_Latency

iostat will show you infor about iowaits, which are usually disk I/O
related.

beww