Feedback on new feature: energy performance settings

[Harald Sitter]

On Wed, Aug 12, 2020 at 7:52 PM John Salatas <jsalatas at ictpro.gr> wrote:
> It would be good to have a confirmation from more users, before deciding
> whether we will expose the governor settings in the GUI or not.

# AMD Ryzen 7 4800H (acpi-cpufreq):

schedutil/ondemand/conservative: idle at minimum configured frequency,
scales up to maximum freq when running `stress -c 16`
performance: strangely seems to behave more or less exactly like the
scaling governors, might well be a bug in my kernel version as the
documentation says it should run at cap.
powersave: always at minimum frequency

since lower frequency also means lower wattage powersave saves power
by keeping the frequency at the lowest configured value (which on this
system is 1.4ghz; maximum is 2.9 with boost at 3.0-3.2 or so).

2.2W with screen on standby but wifi on.

using schedutil and running stress on all cores for about 5 minutes
the discharge rate is at 33W with frequency being at cap + boosted and
the fan running like crazy.

using powersave and the same stress scenario the discharge rate is at
10W with frequency being locked at configured minimum.

# ARM Cortex-A72 on rpi4 (cpufreq-dt):
same as ryzen except performance behaves as expected and keeps the
cores at the maximum frequency (i.e. as would be expected from kernel
docs)

# ARM Cortex-A9 MPCore (cpufreq-dt):
only seeing performance and schedutil as available governors. behave
same as the A72

HTH
HS