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linux-signed-lowlatency-hwe-6.5 package

  1. Bug #2051733
  2. Comment #6

Comment 6 for bug 2051733

Revision history for this message
Doug Smythies (dsmythies) wrote : Re: Specifying nohz_full disables CPU frequency scaling

Yes, this happens also with the mainline kernel.

It also happens with the intel_cpufreq CPU frequency scaling driver (i.e. the intel_pstate driver in passive mode), and all governors. It also happens with the acpi-cpufreq CPU frequency scaling driver, and all governors. However the manifestations of the incorrectly reported scaling_cur_freq can be anywhere from wrong to correct.

Example 1: 100% load on all 12 CPUs; acpi-cpufreq; schedutil:

doug@s19:~$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:4800005
/sys/devices/system/cpu/cpu10/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu11/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu1/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu2/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu3/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu4/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu5/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu6/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu7/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu8/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu9/cpufreq/scaling_cur_freq:4101000

except for CPU 0, which seems to be reporting as is it is using a different driver, the results are correct.

Example 2: 100% load on CPU 4 only; acpi-cpufreq; ondemand:

doug@s19:~$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq:4799876
/sys/devices/system/cpu/cpu10/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu11/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu1/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu2/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu3/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu4/cpufreq/scaling_cur_freq:4101000
/sys/devices/system/cpu/cpu5/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu6/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu7/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu8/cpufreq/scaling_cur_freq:800000
/sys/devices/system/cpu/cpu9/cpufreq/scaling_cur_freq:800000

Again, except for CPU 0, the results are correct.