Processor Power Gating via Architectural State Storage
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Solution Overview
Problem
Current power management techniques in integrated circuits (ICs) are inefficient during idle states, as they require operating system awareness and complex software implementations to power down processors, which increases development costs and reduces control for IC designers, especially in processor architectures lacking microcode support.
Innovation Solution
Implementing power gating instructions that allow processors to save their architectural state and gate power during idle periods without operating system involvement, using secure modes and firmware to manage power states, enabling net power savings without requiring OS awareness, and utilizing microcode modifications in supported architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the processor maintains power to all circuitry during idle states, then the processor can quickly resume execution, but power consumption increases significantly
Solution Approach 1:
The processor is divided into multiple independent segments or blocks, each capable of being powered down individually during idle states. The power gating mechanism selectively gates power to specific processor segments based on their activity status, allowing non-active segments to consume minimal power while active segments maintain full functionality.
Solution Approach 2:
The system performs preliminary actions by saving the architectural state to non-volatile storage before gating power, and pre-configures power gating control logic to enable rapid restoration. This preliminary preparation allows the processor to quickly resume execution without maintaining continuous power to all circuitry.
2Use of energy by moving object
If the processor powers down during idle states, then power consumption decreases, but the complexity of power management increases
Solution Approach 1:
The processor implements self-service power management through automated state saving and restoration mechanisms. The power management logic is integrated into the processor architecture itself, allowing it to autonomously manage its own power states without requiring external control, thereby reducing overall system complexity.
Solution Approach 2:
The power gating mechanism is designed with universal applicability across different processor architectures and idle state scenarios. The same basic power gating infrastructure can handle various idle conditions (halts, waits, sleep modes) and different processor configurations, reducing the need for architecture-specific power management implementations.
3Ease of operation
If operating system awareness is required for power management, then power states can be controlled, but development costs and implementation complexity increase
Solution Approach 1:
An intermediary power management interface is introduced between the operating system and the processor power gating mechanism. This interface translates high-level OS power management requests into low-level processor control signals, shielding the OS from the complexity of direct power management while maintaining effective control.
Solution Approach 2:
The complex power management logic is extracted from the operating system and embedded directly into the processor hardware. This extraction eliminates the need for OS-aware power management software, reducing development costs and simplifying implementation while maintaining precise control over processor power states.
4Device complexity
If the processor lacks microcode support, then hardware simplicity is maintained, but power management control is reduced
Solution Approach 1:
The power management system implements dynamic control through hardware-based state detection and response mechanisms. The processor dynamically transitions between powered and powered-down states based on real-time idle detection, with the control logic adapting to different idle scenarios without requiring microcode interpretation.
Solution Approach 2:
The processor maintains hardware simplicity while achieving effective power management control through self-service mechanisms. The processor autonomously detects idle states, saves its architectural state, and gates power without external microcode intervention, preserving hardware simplicity while maintaining full power management control.
Data Source
AI summary
Processor power may be managed by executing state storage and power gating instructions after receiving an idle indication. The idle indication may be received while the processor is executing instructions in a first mode, and the processor may execute the state storage and power gating instructions in a second mode. The state storage and power gating instructions may be inaccessible to the processor when operating in the first mode.