[mythtv-users] can we all get together and figure out cpu usage - Please respond

[Bruce Markey]

Wally Wallace wrote:
...
> One thing I am very curious about. Are people who are saying mythtv is
> using only %30-40 reading top correctly? When I watch livetv I tend to
> have 5-10 mythbackend threads and 4 or 5 mythfrontend threads. Now this
> is what I think - those that report low cpu usage aren't reporting total
> cpu usage they are just reporting usage in the first thread in the list.

This is why I suggest checking the idle time in section 19.4.
It doesn't matter what is pegging the CPU, if there isn't
time to encode all the frames, frames will be dropped.

Only the video encoding thread should be using significant
CPU. If the audio thread is using more than 10-20% that
may be a clue for a problem with audio recording. If I
record something that takes ~48% for video, ~7% audio and
41% idle, no other backend threads or processes take more
than 2% CPU. Adding up the threads also doesn't account for
sys cpu which shouldn't be more than a few % anyway. So,
you're right that reporting the video thread only is a bit
optimistic. It should be the bulk of the CPU time but idle
time is the important indicator.

> The problem here is that X on my frontend uses 30-50% cpu and I don't
> know why.

Did you ever think "What the hell" I might as well try a
simple window manager like 'twm" to see if that makes a
difference? 30-50% cpu for the X server is not normal and
is likely related to your other problems.

Another variable that is often overlooked is signal quality.
Snow is hard to compress. A poor signal can drive your CPU
usage way up (and gathering stats from others won't account
for this). Try connecting a DVD player directly into your
tuner card and see if it does significantly better. If so,
call your cable company. Another indicator of this is if
your idle time varies significantly depending on which
channel you record.

--  bjm