Mailing List Archive: MythTV: Users

Mythfrontend idle cpu consumption help

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mtdean at thirdcontact

Nov 18, 2009, 2:17 PM

Post #101 of 107 (95 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

On 11/18/2009 04:35 PM, jansenj wrote:
>> Also, when using OpenGL painter, the nvidia-settings OpenGL (not video)
>> Sync to Vblank setting may have an effect.
>>
> 1. I'm using the Qt painter, but I've seen the same issue with the GL
> painter.
> 2. I've tried that setting in poth positions for the Qt painter, still have
> the issue.

The OpenGL sync to vblank won't have an effect when using the Qt painter.

Since you seem to be using CPU frequency scaling, if you're using an AMD
processor, frequency scaling may decrease the memory speed/bandwidth,
which could artificially increase the CPU usage. Can you test it with
the governor set to Performance?

Mike
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jansenj+myth at gmail

Nov 18, 2009, 2:37 PM

Post #102 of 107 (90 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

> Since you seem to be using CPU frequency scaling, if you're using an AMD
> processor, frequency scaling may decrease the memory speed/bandwidth, which
> could artificially increase the CPU usage. Can you test it with the
> governor set to Performance?
>
>
As I think I said before, I think this almost seems like a "busy wait"
somewhere. Because when I told my cpu to go to 2Ghz, it STILL utilized
14%. Something is consuming ~130ms of time every second almost regardless
of CPU speed.

jarpublic at gmail

Nov 18, 2009, 2:45 PM

Post #103 of 107 (91 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

> As I think I said before, I think this almost seems like a "busy wait"
> somewhere. Because when I told my cpu to go to 2Ghz, it STILL utilized
> 14%. Something is consuming ~130ms of time every second almost regardless
> of CPU speed.

I saw the same thing. I scaled my CPU a while back from Ondemand at
1.4 GHz to Performance 2.7 GHz and the CPU utilization stayed ~14%.
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mtdean at thirdcontact

Nov 18, 2009, 2:46 PM

Post #104 of 107 (91 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

On 11/18/2009 05:37 PM, jansenj wrote:
>> Since you seem to be using CPU frequency scaling, if you're using an AMD
>> processor, frequency scaling may decrease the memory speed/bandwidth, which
>> could artificially increase the CPU usage. Can you test it with the
>> governor set to Performance?
> As I think I said before, I think this almost seems like a "busy wait"
> somewhere. Because when I told my cpu to go to 2Ghz, it STILL utilized
> 14%. Something is consuming ~130ms of time every second almost regardless
> of CPU speed.

Yes, there's a very tight select/poll loop in Qt's event dispatcher for
*nix systems that can be hit in some circumstances. But it's all just a
"wait for something" loop, so it doesn't really affect anything else
running on the system (as it's fine waiting while something else runs or
while the loop runs).

Mike
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jarod at wilsonet

Nov 18, 2009, 3:09 PM

Post #105 of 107 (90 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

On Nov 18, 2009, at 5:46 PM, Michael T. Dean wrote:

> On 11/18/2009 05:37 PM, jansenj wrote:
>>> Since you seem to be using CPU frequency scaling, if you're using an AMD
>>> processor, frequency scaling may decrease the memory speed/bandwidth, which
>>> could artificially increase the CPU usage. Can you test it with the
>>> governor set to Performance?
>> As I think I said before, I think this almost seems like a "busy wait"
>> somewhere. Because when I told my cpu to go to 2Ghz, it STILL utilized
>> 14%. Something is consuming ~130ms of time every second almost regardless
>> of CPU speed.
>
> Yes, there's a very tight select/poll loop in Qt's event dispatcher for *nix systems that can be hit in some circumstances. But it's all just a "wait for something" loop, so it doesn't really affect anything else running on the system (as it's fine waiting while something else runs or while the loop runs).

I've paid zero attention to this thread, but is this possibly relevant?:

http://www.nvnews.net/vbulletin/showthread.php?t=140708&highlight=100%25+cpu

--
Jarod Wilson
jarod[at]wilsonet.com

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stichnot at gmail

Nov 18, 2009, 3:14 PM

Post #106 of 107 (91 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

On Wed, Nov 18, 2009 at 3:09 PM, Jarod Wilson <jarod[at]wilsonet.com> wrote:
> I've paid zero attention to this thread, but is this possibly relevant?:
>
> http://www.nvnews.net/vbulletin/showthread.php?t=140708&highlight=100%25+cpu

Seems unlikely since people here are talking about 100% CPU
utilization in the mythfrontend process, not the Xorg process. But
it's certainly worth a try.

Jim
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jansenj+myth at gmail

Nov 18, 2009, 6:50 PM

Post #107 of 107 (80 views)
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Re: Mythfrontend idle cpu consumption help [In reply to]

>
> Yes, there's a very tight select/poll loop in Qt's event dispatcher for
> *nix systems that can be hit in some circumstances. But it's all just a
> "wait for something" loop, so it doesn't really affect anything else running
> on the system (as it's fine waiting while something else runs or while the
> loop runs).
>
>
> Which, again, I would be fine with if everyone was experiencing the same
behavior.

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