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SubjectWhat should cpuinfo_cur_freq mean?
There are least three choices for what the "current frequency" is:

1. The frequency that the cpufreq driver thinks it has requested.
This shows up in scaling_cur_freq.

2. The frequency that is actually programmed into the CPU. This is
what acpi_cpufreq's cpuinfo_cur_freq reports.

3. A measurement of the number of cycles per unit time that are
currently or recently happening. This is what intel_pstate reports.

The fact that acpi-cpufreq and intel_pstate behave differently here is
unfortunate. I have servers [1] with broken BIOS that occasionally
screw up the requested P-state (i.e. MSR 0x199). With acpi_cpufreq
loaded, I can at least tell that there's a problem by reading
cpuinfo_cur_freq. With intel_pstate loaded, I get a rapidly
fluctuating value that depends on Turbo's current mood.

Can we separate out these concepts into separate sysfs files?

[1] These are fully up-to-date, recent generation Dell servers.


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