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

[Qian Cai]

On 6/24/2021 6:48 AM, Ionela Voinescu wrote: 
> Not if the counters are implemented properly. The kernel considers that
> both reference and delivered performance counters should stop or reset
> during idle. The kernel would not account for idle itself.
> 
> If the reference performance counter does not stop during idle, while
> the core performance counter (delivered) does stop, the behavior above
> should be seen very often.
> 
> Qian, do you see these small delivered performance values often or
> seldom?

FYI, the latest data point it that on the new kernel, the delivered performance does match the cpufreq_cur_freq. IOW, feedback_ctrs works fine. Also, "powersave" governor could bring down the scaling_cur_freq to scaling_min_freq. Right now, looks like the puzzles on this particular system as mentioned in the previous post are,

1) lowest_freq/lowest_perf != scaling_min_freq
2) CPPC + schedutil is not able to scale down CPUs.