[mythtv] Memory requirements of current f/e

Daniel Kristjansson danielk at cuymedia.net
Thu Apr 13 15:15:00 UTC 2006

On Thu, 2006-04-13 at 08:26 +0100, Ed W wrote:
> >I'm not sure either of these are actually leaks. The EIT parsing
> >just took a lot of memory. But there is now rate limiting which
> >stops new EIT events from being added to our parsing list when
> >the number of EIT events cached for parsing exceeds 2000.
> >
> >And the OSD cache probably just consumes a lot of memory because
> >is keeps decoded copies of your OSD at all resolutions you've
> >used so far. This also needs some cache size limits...
> >  
> I haven't had any time to do any tracking on these "leaks" so far, but I 
> was seeing:
> With EIT disabled:
> - a very steady rise by 30Mb each time I left or entered watching a 
> recording (I guess this sounds like the OSD cache leaking?)
I think Isaac may have just fixed some of this.

> - A rise by about 10Mb each time I slide up or down the list of 
> recordings available (it goes up by about 20mb, then drops down 10Mb a 
> bit later)
This is probably the preview generation, this should be freed as soon
as the preview has been generated, which can take a while on an Epia.

> - Backend is consistently at around 23Mb reserved, but around 200Mb in 
> swap (at least it's mostly in swap). CPU usage is 0.7% while recording a 
> show
I don't know what is consuming all the memory here, what kinds of
recorders are you using?

> With EIT
> - Backend was at 1.2Gb of swap when I checked the tv each morning (only 
> left it two nights)
My guess is that the EIT data was getting backed up, depending on the
fixup routine you use it can take some time to process the EIT data.
As of yesterday the number of cached EIT's for processing has been
capped at a little over 2000, before there was no cap. I've also
tried to make the EIT event class a bit smaller than it used to be..

> - Watching live tv was showing the backend steadily clicking up 300Kb to 
> 1-2Mb every few mins (seemed ok when watching recordings as you would 
> expect)
Sounds like EIT; this should be considerably better with today's SVN.

> - Frontend was clicking up 300Kb to 1-2Mb while watching anything, even 
> old recordings made well before my recent switch
Might be a leak, Issac just checked something in which should address
some of this. But also it could be MHEG. If you don't want the
interactive TV stuff you can now disable MHEG data collection it in
your recording profile by changing the type from 'default' to 'tv only'.
Dave Mathews is also working on a patch to address some MHEG issues.

> - Quiting the frontend while watching a recorded show would give back 
> 100Mb or so and then I can get another 10 mins or so of viewing before 
> it runs out of memory.  ie *some* of the ram is returned, but not the 
> bulk of it.
Issac just checked in something from Jim that would prevent the MHEG
parser from quitting. See how it is now.

> Please don't see any of the above as complaints!  The new EIT scanner is 
> *excellent* work! Just trying to get some info really on where to look 
> to try and debug a few of these issues - I only have a single box which 
> is also the main house TV, so in general I need to make small 
> development steps and try to avoid having it broken for too long
I'm not upset by any of your comments :) I've been actively working
on addressing some of the EIT issues this week, and Dave is working
on an MHEG patch. MHEG seems like something that might be causing some
of your issues; try disabling it in your recording profiles for now.

-- Daniel

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