[mythtv-users] CPU load when watching TV

lee lee at yun.yagibdah.de
Sun Dec 13 14:19:07 UTC 2009

On Sat, Dec 12, 2009 at 07:56:25PM -0500, Rod Smith wrote:

> Given this comparison, if you're watching HD content, your CPU load is 
> probably reasonable -- I'm assuming the load is jumping around between your 
> four cores, so you're not really running all four cores at 40% 
> simultaneously.

Yes, it's over all the cores. Two or three of them were pretty low,
one higher.

> > That way, it's hard to tell what load mythtvfrontend actually
> > causes. But kaffeine, for example, doesn't cause a load like
> > mythtvfrontend does.
> It's possible that MythTV is doing more than Kaffeine.

Yeah, it was using CPU to decode. After switching to VDPAU, the load
is lower, and the picture is a lot better.

> Note that using VDPAU just 
> shifts much of the decoding burden from the CPU to the GPU. Since you say 
> your concern is with power consumption, I'm not sure this would really be an 
> improvement. You could always measure it with an appropriate meter, of 
> course.

I'll have to find out more about options to save power first and then
get a meter to see what's actually going on. I'd like to use suspend
to disk, but it seems too dangerous. Maybe suspend to RAM is better,
but what if the power fails? I could have the disks spin down, but
they are being accessed too much to reasonable do that.

It's ok while I'm using the computer, but still I don't want to use
more power than needed. Saving power is another issue by itself ...

> > > > Another observation: In my experience, misconfiguring X can result in a
> > > >  heavy CPU load from X, vs. from the MythTV frontend.
> >
> > Well, I haven't had this problem yet.
> Earlier you said you couldn't identify where your CPU load was
> coming from.

Yes, xosview doesn't tell where it comes from, and top doesn't tell me
much, either.

> > But mythtvfrontend as well as 
> > mythtv-setup make the mouse pointer invisible once it enters the
> > window. Is there a way to change that?
> I seem to recall there's a setup option that controls this -- or at least that 
> should. (One of my minor problems with 0.22 is that the mouse pointer tends 
> to reappear if I switch to a text-mode console and then switch back to X.) I 
> don't recall exactly where this option is, though.

It's somewhere in the blayback settings where I switched to VDPAU :)
> In my experience, database 
> updates are the biggest problem, because they tend to run without being 
> niced.

That shouldn't matter? Or is the database really under a lot of load

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