[Bug 211305] schedutil selects low P-States on AMD EPYC with frequency invariance

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=211305

--- Comment #12 from Rafael J. Wysocki (rjw@rjwysocki.net) ---
(In reply to Matt McDonald from comment #10)
> Okay so that's *way* worse. 
> 
> Everything's limited and locked to 2.2GHz. And yes, it's actually running at
> 2.2GHz, it's not misreporting. My Geekbench score was less than a third of
> what it should be
> 
> cat /proc/cpuinfo | grep MHz
> cpu MHz               : 2200.000
> cpu MHz               : 2200.088
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2199.982
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000
> cpu MHz               : 2200.000

This actually doesn't mean that the CPUs are running at the given frequency.

> 
>  cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
> 2199680
> 2199981
> 2195932
> 2199979
> 2195634
> 2198726
> 2199437
> 2195587
> 2197662
> 2198924
> 2198856
> 2195535
> 2196402
> 2199234
> 2199880
> 2195064

And so this.

> analyzing CPU 0:
>   driver: acpi-cpufreq
>   CPUs which run at the same hardware frequency: 0
>   CPUs which need to have their frequency coordinated by software: 0
>   maximum transition latency:  Cannot determine or is not supported.
>   hardware limits: 2.20 GHz - 6.00 GHz
>   available frequency steps:  3.80 GHz, 2.80 GHz, 2.20 GHz
>   available cpufreq governors: performance schedutil
>   current policy: frequency should be within 2.20 GHz and 2.20 GHz.
>                   The governor "schedutil" may decide which speed to use
>                   within this range.
>   current CPU frequency: 2.20 GHz (asserted by call to hardware)
>   boost state support:
>     Supported: yes
>     Active: no
>     Boost States: 0
>     Total States: 3
>     Pstate-P0:  1000MHz
>     Pstate-P1:  700MHz
>     Pstate-P2:  500MHz
> 
> 
> Both schedutil and performance governors had no effect. 
> 
> But I do see in that cpupower output that it says the hardware limits happen
> to be 2.20GHz to 6.0GHz.

That's as expected.

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