[mythtv-users] Mythfrontend idle cpu consumption help

Brad Templeton brad+myth at templetons.com
Wed Nov 4 08:28:41 UTC 2009

On Tue, Nov 03, 2009 at 01:34:10PM -0800, Jim Stichnoth wrote:
> On Tue, Nov 3, 2009 at 7:09 AM, Daniel Kristjansson
> <danielk at cuymedia.net> wrote:
> > On Mon, 2009-11-02 at 14:07 -0800, Brad Templeton wrote:
> >> On Fri, Oct 30, 2009 at 12:22:22PM -0400, jansenj wrote:
> >> I have found much greater use of CPU by the more recent mythfrontends
> >> over the last year in general.   For example, while my system would
> >> get decent idle times playing HD content and run quietly, now the
> >> computer is routinely heating up (and running the fan loud) with
> >> nothing else on the machine sucking CPU except xorg and mythfrontend.
> >> (ie. no mythcommflag, which was the only reason the fan would get
> >> loud before, or perhaps a runaway firefox page.)
> >
> > I can't speak for your particular machine. However I had
> > noticed this too on one frontend but after some investigation
> > found out that the 0.21 MythTV never allowed the CPU to enter
> > a low power state, so it only appeared to be using less CPU.
> > When I forced the CPU out of powersaving mode the CPU usage
> > looked the similar when using the same theme.
> >
> > Some themes do consume more resources because they use alpha
> > blends, animations and clocks. This is especially true if you
> > use the Qt renderer, which does these things using the CPU
> > instead of the GPU.
> >
> > During my investigation I also noticed the plasma rendering
> > engine in KDE 4.x consumes more resources than any other
> > application on the machine. For a dedicated MythTV machine
> > it is a good idea to use something lightweight instead.
> I have been noticing the same kind of behavior since moving to 0.22,
> which I am running on 3 IONITX frontends (one of which is also a slave
> backend).  After booting up, the frontend consumes about 2% CPU
> displaying the main menu, which is fine.  Over the next few days, this
> CPU usage gradually increases, until it's at around 10%.  When it gets
> to 10%, the response time gets much worse.  For example, from the main
> menu, selecting Watch Recordings may pause for 4-5 seconds while still
> displaying the main menu, then it displays a blank Recordings page for
> another 5+ seconds, and finally displays the recordings.  The same
> sluggish performance happens for MythVideo as well.
> When it reaches this funk, restarting the frontend doesn't help.  It
> comes back up consuming 10% CPU like before.  I haven't found anything
> other than rebooting to get the zippy performance back.  (Makes me
> feel like it's a Windows machine!)
> Any ideas for explaining this behavior?
> Jim
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I have also seen this a lot on earlier versions of 0.22 though it is not as bad
now, always on kubuntu.   However, the long pauses would be after sitting idle
for a long time, and seemed likely to be caused by swapping though there was
not the obvious disk noise of that.   The delays were indeed quite annoying, but
I don't get them nearly as much as before but still some.

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