55 lines
2.2 KiB
C++
55 lines
2.2 KiB
C++
/*
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* CpuPower.hpp
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* Intel CPU power management: HWP frequency scaling, C1E promotion,
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* and the package thermal governor.
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* Copyright (c) 2026 Daniel Hammer
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*/
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#pragma once
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#include <cstdint>
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namespace Hal {
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namespace CpuPower {
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// Snapshot of the power/thermal state for SYS_POWERINFO and logging.
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struct Snapshot {
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bool HwpActive;
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bool Throttling;
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uint8_t TempC; // package temperature (0 = unknown)
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uint8_t TjMaxC; // hardware throttle temperature
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uint8_t HighestPerf; // HWP performance range (ratio units)
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uint8_t LowestPerf;
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uint8_t CurMaxPerf; // governor's current performance ceiling
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uint8_t Epp; // energy/performance preference in effect
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uint32_t BaseMHz; // CPUID base frequency (0 = unknown)
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uint32_t MaxMHz; // CPUID max turbo frequency
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uint32_t EffMHz; // measured average active frequency (BSP)
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};
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// BSP: detect features, enable HWP with a balanced energy preference,
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// enable C1E promotion, and prime the thermal governor. Must run
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// before the APs boot so they can pick up the shared policy.
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void InitializeBsp();
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// AP: per-CPU MSR setup (C1E promotion + initial HWP request).
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void InitializeAp();
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// Re-apply the HWP request on the calling CPU if the governor changed
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// the performance ceiling since this CPU last applied it. Cheap (one
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// relaxed atomic compare when nothing changed) - safe in tick paths.
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void ApplyPolicyIfChanged();
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// Thermal governor step. BSP-only; rate-limited internally, so it can
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// be called from every maintenance pass.
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void ThermalTick(uint64_t nowMs);
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// Redo the BSP MSR setup after S3 wake (HWP enable and POWER_CTL do
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// not survive suspend).
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void ReapplyAfterWake();
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// Fill a snapshot for SYS_POWERINFO. Returns false when the CPU
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// exposes none of the relevant features (e.g. under QEMU).
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bool GetSnapshot(Snapshot& out);
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};
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};
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