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SubjectRe: intel_pstate: Lowest frequency not reached with Intel i7-6700
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Dear Doug,


Thank you for your reply.

On 12/13/18 00:06, Doug Smythies wrote:
> On 2018.12.12 13:40 Paul Menzel wrote:
>
>> Using *powersave* as P-state selection algorithm, on an idle system
>
> Define "idle system".
> If your computer is running a GUI, or is even a server without a GUI
> but with many services running, then "idle" really isn't.
> Below is from my test server, with many services disabled, so
> "idle" really is quite "idle"
>
> doug@s15:~/temp$ sudo turbostat --Summary --quiet --show Busy%,Bzy_MHz,PkgTmp,PkgWatt --interval 15
> Busy% Bzy_MHz PkgTmp PkgWatt
> 0.01 1608 27 3.71
> 0.01 1619 27 3.71
> 0.01 1600 28 3.71
> 0.01 1600 28 3.70
>
> Note that p state 16 (1600 MHz) is the minimum for my older i7-2600k
> processor.

The thing is, on an Intel Kaby Lake laptop with Ubuntu 18.10 and GNOME
running, it goes down to the lowest listed frequency.

>> Shouldn’t it go down until 800 MHz?
>
> We would need some actual busy information, turbostat is the
> recommended tool, to know for sure.

Here you go.

```
tools/power/x86/turbostat> sudo ./turbostat --Summary --quiet --show Busy%,Bzy_MHz,PkgTmp,PkgWatt --interval 15
Busy% Bzy_MHz PkgTmp PkgWatt
3.59 1167 31 1.68
3.21 903 31 1.34
3.21 906 31 1.34
3.27 901 31 1.35
8.23 2715 30 2.32 ← stopping GDM (systemctl stop gdm)
2.95 915 30 1.18
2.91 906 30 1.18
2.92 903 30 1.17
2.90 900 29 1.17
2.89 903 29 1.18
2.91 903 30 1.18
2.89 903 29 1.18
2.89 900 29 1.18
2.90 903 30 1.18
2.90 903 29 1.17
2.90 903 29 1.17
2.90 900 29 1.16
2.90 903 29 1.14
2.90 903 28 1.11
2.90 903 29 1.10
2.91 900 29 1.16
2.91 903 29 1.14
2.90 903 29 1.12
2.90 903 29 1.16
2.90 900 28 1.17
2.92 903 29 1.16
2.90 903 29 1.16
2.90 903 29 1.16
```

800 MHz should be enough to keep GDM running, shouldn’t it?
Otherwise only SSH was running.


Kind regards,

Paul

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