Re: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency invariance

On 6/25/2021 6:21 AM, Ionela Voinescu wrote:

quoted

scaling_driver: acpi_cppc

                  ^^^^^^^^^
I suppose you mean "cppc-cpufreq"?

"acpi_cppc" is not a scaling driver option.

Ionela, yes. Sorry about that.

So your CPUs run at frequencies between 200MHz and 280MHz?

2000 to 2800 MHz.

Based on your acpi_cppc information below I would have assumed 2GHz as
lowest nonlinear and 2.8GHz as nominal. The reason for this is that
according to the ACPI spec the frequency values in the _CPC objects are
supposed to be in MHz, so 2800 MHz for nominal frequency would be
2.8GHz.

When you try more governors, make sure to check out the difference
between scaling_cur_freq and cpuinfo_cur_freq at [2]. The first gives
you the frequency that the governor (schedutil) is asking for, while the
second is giving you the current frequency obtained from the counters.

So to check the actual frequency the cores are running at, please check
cpuinfo_cur_freq.

The problem is that all CPUs are never scaling down. "cpuinfo_cur_freq" and "scaling_cur_freq" are always the 2800 MHz on all CPUs on this idle system. This looks like a regression somewhere as in 5.4-based kernel, I can see "cpuinfo_cur_freq" can go down to 2000 MHz in the same scenario. I'll bisect a bit unless you have better ideas?