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

[Qian Cai]

On 6/21/2021 5:19 AM, Viresh Kumar wrote:
> CPPC cpufreq driver is used for ARM servers and this patch series tries to
> provide counter-based frequency invariance support for them in the absence for
> architecture specific counters (like AMUs).

Viresh, this series works fine on my quick tests so far. BTW, I noticed some strange things even with the series applied mentioned below when reading acpi_cppc vs cpufreq sysfs. Do you happen to know are those just hardware/firmware issues because Linux just faithfully exported the register values?

== Arm64 server Foo ==
CPU max MHz:                     3000.0000
CPU min MHz:                     1000.0000

/sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf
300
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq
1000
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf
200
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf
100
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq <--- should be 3000?
2800
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf <--- should be 300?
280
/sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf
100

== Arm64 server Bar ==
CPU max MHz:                     3000.0000
CPU min MHz:                     375.0000

/sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf <--- should be 3000? There is no cpufreq boost.
3300
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq <--- don't understand why 0.
0
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf
375
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf
375
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq <--- ditto
0
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf
3000
/sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf
100