Processor Power State Transitions Using Residency Timers
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Solution Overview
Problem
Modern computer systems face inefficiencies in power management, particularly in transitioning between power states, leading to unnecessary power consumption and latency penalties when entering deeper power management states without adequate conditions being met.
Innovation Solution
A computer processing device and method that transition among multiple power management states and sub-states, using entry conditions and residency timers to determine optimal power state transitions, allowing for efficient power management by entering deeper states only when latency tolerance is met, thereby conserving power while minimizing latency penalties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the system enters deeper power management states to save power, then power consumption is reduced, but latency penalty increases
Solution Approach 1:
The power management states are segmented into multiple levels (first power management state, second power management state with sub-states, third power management state), allowing the system to choose appropriate depth based on conditions. This segmentation enables fine-grained control over the trade-off between power savings and latency penalties.
Solution Approach 2:
The system dynamically transitions between different power management states and sub-states based on real-time conditions such as residency timer expiry and entry condition satisfaction. The dynamic state machine adjusts the power state depth adaptively, optimizing the balance between power consumption and latency requirements.
2Loss of energy
If the system enters deeper power management states frequently, then power savings increase, but system complexity increases
Solution Approach 1:
The system performs preliminary checks of entry conditions before transitioning to deeper power management states. By evaluating conditions in advance and using residency timers to predict idle periods, the system avoids unnecessary state transitions and simplifies the decision-making process, reducing overall management complexity while maintaining effective power savings.
3Productivity
If the system uses residency timers to determine state transitions, then power management efficiency improves, but device complexity increases
Solution Approach 1:
The residency timer mechanism enables the system to automatically determine when to transition between power states based on elapsed time without requiring complex external control logic. The timer self-manages the transition timing, and the system simply checks whether entry conditions are satisfied when the timer expires, thereby improving efficiency while keeping the control logic relatively simple.
Data Source
AI summary
A computer processing device transitions among a plurality of power management states and at least one power management sub-state. From a first state, it is determined whether an entry condition for a third state is satisfied. If the entry condition for the third state is satisfied, the third state is entered. If the entry condition for the third state is not satisfied, it is determined whether an entry condition for the first sub-state is satisfied. If the entry condition for the first sub-state is determined to be satisfied, the first sub-state is entered, a first sub-state residency timer is started, and after expiry of the first sub-state residency timer, the first sub-state is exited, the first state is re-entered, and it is re-determined whether the entry condition for the third state is satisfied.