Linux PVR addon for MythTV taking lots of resources
#1
Hi all,

We have been using the PVR addon for MythTV for about two months now. It is a very nice piece of work indeed! We use it on an Openelec-client (version 3.0.6), connecting to a Fedora Linux 17 server running MythTV-backend 0.25.3.
There is one niggle we have with the current version (1.6.10) and that is that it feels really slow for the first 15 minutes or so. At start-up, it scans for recordings. We have about 1500-2000 recordings on the server (sorry about that.. Confused) and scanning these takes about 3 minutes. Then, the Television menu is enabled and we can get to the Recordings-section. Still, in the background it appears to be scanning all recordings and while it is doing that, the system feels really slow. It appears to completely freeze every now and then, only to return after a minute or so. After some time, it seems to have completed whatever it was doing in the background and then it feels reasonably fast. I have monitored my server during the activity and I can actually see it using lots of server resources (CPU-usage high, disk IO high, many entries being added to the MythTV-logfile). It goes through this routine every time we start up the client.

My questions: is that normal behavior? Is there something I can do to change this behavior? For instance, can I set it to cache the information about recordings and only retrieve information about new recordings at startup? Or is there perhaps a new version in the works that addresses this issue? I'd be happy to participate in testing.

Other than this, we are very happy with it. We used to use a self-compiled Mythfrontend (both under XBMC and Openelec), but it was hard keeping up with new versions and getting the compilation to complete without errors every time. We have also used Mythbox for quite a while, but we prefer the PVR addon. For setting new recording rules, we use the Mythweb-client.

Please share your thoughts.

Thanks, Frans
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#2
Yeah I know what you mean, it sometimes makes me want to throw something.

Why it has to scan for recordings on startup I do not know. mythtv runs it's own well developed database, why the xbmc frontend thinks it also has to be some kind of backend and cache a whole lot of stuff I simply do not know. Similarly it seems to want to know the whole epg when it simply needs to look in the database for the data it needs to display, rather than caching the whole lot.
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#3
Hi all, here's an update: I think I may have found the cause. Previously, I booted Openelec from a USB-stick. That has now been replaced by a harddisk and that has dramatically improved the situation. Loading all recordings now takes way less than a minute.
The server is still kept quite busy during loading, but now obviously for a much shorter time. This is a big improvement in user experience! I'm happy. :-)
After this observation, I have upgraded the backend to the latest 0.26 release of MythTV. That works fine and did not seem to have had a noticeable impact on the PVR-addon.
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#4
@nickr , @fransgl

Yes PVR addon maintains a cache of recordings and their previews. 2000 recordings is not so big and use small amount of memory. Sure it take few time at startup but then the navigation is much faster than mythfrontend. The bottleneck is not when caching recording themselves but when caching previews: You need a good network speed and you must ban usb disk for backend storage and xbmc client.
About EPG: XBMC maintain cache for number of days you have configured in live tv settings screen, no more. So try to limit number of days and the startup speed will be better. Also i hint to enable "Do not store the EPG in the database" because for MythTv addon (not others pvr addon) it is not necessary because myth-backend db store data already from EIT stream or xmltv. That's not the case for all pvr addon.

Goto System->Settings->TV:
- In EPG fix the number of days (3->7 is a good choice ? but avoid to setup 10 or more).
- In EPG enable "Do not store the EPG in the database"

Also it is possible to add setting to disable previews for very big catalog. Let me know if it is required.
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