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

[Viresh Kumar]

On 25-06-21, 22:29, Qian Cai wrote:
> Ionela, I found that set ACPI_PROCESSOR=y instead of
> ACPI_PROCESSOR=m will fix the previous mentioned issues here (any
> explanations of that?) even though the scaling down is not perfect.

Not sure how this affects it.

> Now, we have the following on this idle system:
> 
> # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
>  	79 1000000
>   	1 1160000
>  	73 1400000
>   	1 2000000
>   	4 2010000
>   	1 2800000
>   	1 860000
> 
> Even if I rerun a few times, there could still have a few CPUs
> running lower than lowest_perf (1GHz).

(Please wrap your lines at 80 columns, it makes it harder to read
otherwise).

I think only the counters stopping on idle can get us that.

> Also, even though I set all CPUs to use "userspace" governor and set
> freq to the lowest. A few CPUs keep changing at will.
> 
> # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
> 	156 1000000
>   	3 2000000
>   	1 760000

I think this is expected since the hardware is in control of frequency
here. The software can only request it to run at X frequency, the
hardware may choose to do something else nevertheless.

-- 
viresh