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pyamsoft / pstate-frequency

Easily control Intel p-state driver on Linux
https://pyamsoft.blogspot.com/
GNU General Public License v2.0
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pstate driver doesn't respect settings #14

Closed pyamsoft closed 6 years ago

pyamsoft commented 9 years ago

The pstate-driver does not respect the settings for minimum, and maximum performance percentages. As a result, even when setting the maximum to be low, the driver will sometimes still run at a max frequency. It also will not respect settings for no_turbo.

This is due in part to the fact that the max cpu_frequency is defined in

/sys/devices/system/cpu/cpu#/cpufreq/scaling_max_frequency

as the turbo boosted frequency max. The acpi-cpufreq driver reports the proper frequency and the rules that are set are observed by the driver and cpu frequencies.

pyamsoft commented 9 years ago

Taken from the intel_pstate kernel documentation:

For contemporary Intel processors, the frequency is controlled by the processor itself and the P-states exposed to software are related to performance levels. The idea that frequency can be set to a single frequency is fiction for Intel Core processors. Even if the scaling driver selects a single P state the actual frequency the processor will run at is selected by the processor itself.

pyamsoft commented 9 years ago

The pstate driver also seems to ignore the values set in the cpufreq and intel_pstate sys directories after a resume from system suspend.