Re: 5.2-rc2: low framerate in flightgear, cpu not running at full speed, thermal related?

From: Pavel Machek
Date: Sun Jun 09 2019 - 07:28:02 EST


Hi!

> When I start flightgear, I get framerates around 20 fps and cpu at
> 3GHz:
>
> pavel@duo:~/bt$ cat /proc/cpuinfo | grep MHz
> cpu MHz : 3027.471
> cpu MHz : 2981.863
> cpu MHz : 2958.352
> cpu MHz : 2864.001
> pavel@duo:~/bt$
>
> (Ok, fgfs is really only running at single core, so why do both cores
> run at 3GHz?)
>
> But temperatures get quite high:
>
> pavel@duo:~/bt$ sensors
> thinkpad-isa-0000
> Adapter: ISA adapter
> fan1: 4485 RPM
>
> coretemp-isa-0000
> Adapter: ISA adapter
> Package id 0: +98.0°C (high = +86.0°C, crit = +100.0°C)
> Core 0: +98.0°C (high = +86.0°C, crit = +100.0°C)
> Core 1: +91.0°C (high = +86.0°C, crit = +100.0°C)
>
> And soon cpu goes to 1.5GHz range, with framerates going down to
> 12fps. That's a bit low.
>
> Room temperature is 26Celsius.
>
> The CPU is Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz . I guess it means
> it should be able to sustain both cores running at 2.5GHz?
>
> Any ideas? Were there any recent changes in that area?

I tried kernel compile. It keeps both cores at 3GHz, temperature goes
up over 95C, and then cpus start going down to 2.3GHz... and then down
to 2GHz... and down to 1.9GHz.

watch bash -c 'sensors; cat /proc/cpuinfo | grep MHz'
Pavel
--
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