MythMusic using all my available CPU

Help with using MiniMyth (except Booting)

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dagnygren
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Posts: 20
Joined: Sun Feb 20, 2011 12:28 pm

MythMusic using all my available CPU

Post by dagnygren » Sun Dec 23, 2012 9:23 pm

Hi!

Have a Zotac ION setup here and am seeing real problems running MythMusic with SPDIF sync dropping out and in quite often.
Always when this happens I can see the CPU load on one core being 100% or very close. After some time the load levels
out over all cores and all is fine again. Have turned off the visualizations.
Also seeing similar problems with LIveTV and recordings.

Allover the CPU load is insanely high for just playing some music - The smallest MP3 player can do it with 1/100 of the power in
my system....

Any hints on something I could tune to get this lower?
Running MiniMyth 0.25.3-82 at the moment.
Would it help to run the 64-bit version?

Best
Dag

JoeHenley
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Posts: 185
Joined: Sun Aug 06, 2006 4:12 pm

Re: MythMusic using all my available CPU

Post by JoeHenley » Sun Dec 23, 2012 11:20 pm

Dag,

Sounds like what was going on in my 0.25.0 system when I used NFS for the server/client sharing. Are you using NFS?

Joe Henley

dagnygren
Member
Posts: 20
Joined: Sun Feb 20, 2011 12:28 pm

Re: MythMusic using all my available CPU

Post by dagnygren » Tue Dec 25, 2012 7:32 pm

Yes, I am using NFS but I found the problem:

It was the powernowd that had problems stepping up the CPU speed fast enough not to cause a cut in the SPDIF stream.
My theory is that when the daemon is running on the same core that the only (?) active process(es) it takes quite some time
to cope with an increased CPU demand. 2-5 seconds it seems.
The reported 100% CPU usage was an artefact of having only some 200MHZ CPU speed :o

As the ION has a very crude and according to Google not so efficient Speedstepping (from P4) I disabled the
use of this alltogether by commenting out MM_CPU_FREQUENCY_GOVERNOR in my minimyth.conf. And sure enough
cannot see any increase in temperature or power consumption.

I am happy to report that I am now playing music fine with 20-25% CPU usage max. Additionally this cured that cutoffs and stuttering I
have seen in playback of Videos, Blurays and recordings !! I have been lookiing for the reason for two years now and am a very happy puppy right now. :D

JoeHenley
Contributor
Posts: 185
Joined: Sun Aug 06, 2006 4:12 pm

Re: MythMusic using all my available CPU

Post by JoeHenley » Tue Dec 25, 2012 9:45 pm

Dag,

Good to hear you got the problem solved!

When I read your solution it occurred to me that, I too, have an Atom powered FE. Perhaps there is some improvement available thru limiting Speedstep on mine too. So I did some looking around.

What I found is that neither your Atom 330 nor my Atom 525, support Speedstep. So it would seem that there should be no effect to either from ANY Speedstep setting. But it does seem to affect yours. Is there something funky with MiniMyth?

My minimyth.conf file leaves the Speedstep setting blank, thus at the default (which is "performance", which I assume means no CPU freq throttling). So it would seem there is no effect to my FE. But now I'm not so sure.

Joe

dagnygren
Member
Posts: 20
Joined: Sun Feb 20, 2011 12:28 pm

Re: MythMusic using all my available CPU

Post by dagnygren » Tue Dec 25, 2012 10:14 pm

Yes, there is no internal speedstepping, but the operating frquency of the Atom can be adjusted
and that is what the daemon does.

An easy check for the current operating frequency is:

Code: Select all

while true
do
  grep MHz /proc/cpuinfo
  sleep 1
done
If the values vary, something is changing your running frquencies.

And I have an Atom D525 in the problematic frontend if that makes a difference.

JoeHenley
Contributor
Posts: 185
Joined: Sun Aug 06, 2006 4:12 pm

Re: MythMusic using all my available CPU

Post by JoeHenley » Wed Dec 26, 2012 5:04 pm

Dag,

I ran your code snippet via telnet while "exercising" the FE and the CPU freq remained constant. So it seems the default setting in minimyth.conf leaves the frequency settings alone. So my concerns were unfounded.

As to where I came up with the idea you were running a 330 Atom.... Seems old age causes you to forget some things AND remember some things that never were. ;-)

Joe Henley

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