Fine grain frequency control with kernel governors
summary
Upstream MDP state CPUfreq driver exposes fine‑grained cppc performance levels instead of ACPI’s three P‑states and maps as many as 155–255 performance steps for some platforms. MSR‑based platforms using the 4 MSR vs shared‑memory cppc implementations show better perf per watt and are enabled by default, while shared‑memory targets lag and remain off by default. EPP hints and max/min curves are implemented in hardware but current kernel governors don’t honor them and need new interfaces and governor changes.
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chapters (6)
- 0:00Introduction and background
- 1:47ACPI P-states and traditional control
- 2:32CPPC and MD State driver
- 5:12MDP State driver details
- 8:32Energy performance hints and EPP
- 10:46Summary and next steps
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