CPU Idle Governor Switching for Runtime Power Management
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Solution Overview
Problem
Conventional CPU idle governor selection techniques select a single governor for each CPU at boot time based on static ratings, failing to adapt to various use cases and neglecting important factors like hardware input, CPU frequency, and battery state, leading to reduced performance and inefficiency.
Innovation Solution
Adaptive selection of CPU idle governors that register multiple governors at boot time and dynamically update them during runtime based on inputs such as CPU type, frequency, utilization, cache size, application context, and battery state to optimize power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single idle governor is selected for each CPU at boot time based on static ratings, then the selection process is simple and fast, but the system cannot adapt to various use cases and hardware conditions leading to reduced performance
Solution Approach 1:
The patent implements dynamic governor selection by transitioning from static boot-time selection to runtime adaptive selection. The system continuously monitors CPU inputs (frequency, utilization, cache size, battery state) and dynamically switches governors based on current conditions, allowing the governor selection process to adapt to changing system states rather than being fixed at boot time.
Solution Approach 2:
The patent introduces feedback mechanisms where the system monitors actual CPU performance metrics (frequency, utilization, cache hit/miss ratios) and uses this information to evaluate governor effectiveness. This feedback loop enables the system to learn from actual performance data and adjust governor selections accordingly, improving adaptability based on real-world behavior rather than static ratings.
2Reliability
If static ratings are used for governor selection, then the selection process is straightforward, but important factors like hardware input, CPU frequency, and battery state are neglected
Solution Approach 1:
The patent changes the selection parameters from static ratings to dynamic CPU-specific parameters including frequency, utilization, cache size, and battery state. By continuously updating these parameters based on actual hardware conditions and using them as selection criteria, the system achieves more accurate governor selection that reflects real-time system state rather than relying on fixed pre-determined ratings.
3Use of energy by moving object
If multiple governors are registered and dynamically selected during runtime, then power efficiency is optimized for specific CPU conditions, but the selection and management process becomes more complex
Solution Approach 1:
The patent segments the governor selection process into distinct phases: registration phase (where multiple governors are registered with different priorities), initial selection phase (boot time selection based on static ratings), and runtime adaptation phase (dynamic selection based on CPU inputs). This segmentation allows the system to manage multiple governors systematically through structured phases rather than treating them as a single complex problem.
Solution Approach 2:
The patent applies partial action by selectively evaluating and switching governors based on specific CPU conditions rather than continuously optimizing all parameters. The system monitors key inputs (frequency, utilization, cache state) and only switches governors when specific thresholds are crossed, avoiding the excessive complexity of continuously reoptimizing all governor parameters while still achieving meaningful power efficiency improvements.
Data Source
AI summary
A method includes registering a set of central processing unit (CPU) idle governors. The method also includes selecting at boot time, for each CPU of a set of CPUs, an initial CPU idle governor from the set of CPU idle governors based on an initial rating associated with each idle governor. The method further includes selecting during run time, for each CPU of the set of CPUs, an updated CPU idle governor from the set of CPU idle governors based on at least one CPU input of a set of CPU inputs associated with each CPU.