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

On 6/25/2021 10:29 PM, 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. 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). 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

Another date point is that set ACPI_CPPC_CPUFREQ_FIE=n fixed the issue that any CPU could run below the lowest freq.

schedutil:
# cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
     80 1000000
     78 1400000
      1 2010000
      1 2800000

userspace:
# cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq  -c
    158 1000000
      2 2000000