[mythtv-users] Howto prevent MythTV flushing/Syncing disk writes (LiveTV/Recordings)

Albert Graham agraham at g-b.net
Tue Mar 18 18:24:41 UTC 2008


David Brodbeck wrote:
> On Mar 18, 2008, at 8:46 AM, Albert Graham wrote:
>   
>> My point with my question is that I think MythTV is "going out of it's
>> way to bypass the write cache" and secure the data to disk!
>>     
>
> IIRC this is because large, chunked writes were causing video skipping  
> on some systems.  Smaller writes tie up the bus for less time.  I  
> could be wrong about that, but I think I read it somewhere on the list.
>   
Hi Dave,

OK, maybe for specific limited old hardware, this could be true, that's 
all the more reason to have this "feature" configurable and give control 
to whoever administers the box.

Also, that argument does not hold much water, because MythTV can handle 
multiple feeds/cards at once, so if you have 5 cards (and I plan to have 
at least 10) you'd be dead in the water.

I imagine the frame buffer side of things is interrupt driven in most 
cases, so if there are no conflicts in the hardware setup it should not 
miss any frames, so write caching would actually improve this situation.

I think when people setup MythTV backend they'd rather use modern 
powerful hardware (as best they can afford).



Albert.



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