[mythtv] High CPU usage during playback.

Carl mythtv at carldunham.com
Wed Mar 10 22:10:01 EST 2004


Sorry to post speculation without doing further testing, but at one point I 
noticed quite a bit of sql activity from the front end. All my high cpu 
problems went away when I disabled previews, do I didn't pursue it, but at 
the same time I had a couple of bad recordings (in the recorded table but 
no .nuv file, or an empty one). Things definitely seemed to go haywire if I 
nav'd over the entry in question in the Watch Recorded screen.

PVR-350, Epia 800 (C3). Gentoo.

Hope this helps. If I have time later, I can turn previews back on and try to 
reproduce this...


On Wednesday March 10 2004 17:55, Neil Whelchel wrote:
> Hello again,
> I tried it with the preview on and off and in both cases it didn't make
> any difference at all. In both cases there was 100% CPU usage and many
> interruptions in playback. I already had a look at the other messages
> about CPU usage and none of them really applied to what I am dealing with
> here. In my case I am NOT having a problem while watching live TV, it is
> only a problem while watching something that is pre-recorded. As far as I
> can tell, the problem is that the mythfrontend main thread is using a huge
> amount of CPU with calls to processEvents().
>
> Clarification:
> The mythfrontend player thread in both cases uses the same amount of CPU
> and I think it is within reason as to about what it should be.
> This has nothing whatsoever to do with mythbackend as it is on a different
> machine.
>
> In myhtfrontend/main.cpp startTV() the code fragment looks something
> like...
>         {
>             qApp->unlock();
>             qApp->processEvents();
>             usleep(100000);
>             qApp->lock();
>         }
>
> And in mythfrontend/playbackbox.cpp PlaybackBox::play() it looks like...
>         {
>             qApp->unlock();
>             qApp->processEvents();
>             usleep(50);
>             qApp->lock();
>         }
>
> Changing the latter from 50 to 100000 fixes the problem for me.
> (The CPU usage is about what it should be both during playback of
> recordings and live TV.)
> It doesn't appear to have any side effects that I am able to find, that is
> why I posted my original question here:
> Is there a reason that in one case (live TV) the usleep is for 100000 and
> in the other (playback of a recording) it is for 50?
>
>
> -Neil Whelchel-
> First Light Internet Services
> 760 366-0145
> - We don't do Window$, that's what the janitor is for -
>
> On Wed, 10 Mar 2004 steve at nexusuk.org wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On Wed, 10 Mar 2004, Neil Whelchel wrote:
> > > I have been having some issues with my 1Ghz VIA CPU keeping up while
> > > playing back pre-recorded videos (100% CPU usage with video pausing a
> > > few tenths of a second every second or two), however it does fine (40%)
> > > playing live TV.
> >
> > See the previous thread discussed over the past week about high CPU usage
> > in the CVS version - it seems that (for some people?) the CVS version is
> > leaving the preview video playing in the background while watching a
> > recording.  Try turning off the preview video in the config and see if it
> > fixes your problem.
> >
> > - --
> >
> >  - Steve                                            
> > http://www.nexusuk.org/
> >
> >      Servatis a periculum, servatis a maleficum - Whisper, Evanescence
> >
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.2.3 (GNU/Linux)
> > Comment: Public key available at http://www.nexusuk.org/pubkey.txt
> >
> > iD8DBQFATv/F5zUOsIV3bqERAjYPAJ0RkNnlcdA7xr/g5GCuRLVSnC90vgCglZB4
> > 1O3lRM8OIhuPuQs2UvatMZ8=
> > =LRtz
> > -----END PGP SIGNATURE-----

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