Bifurcated Thread Scheduler for Automatic Low Power Mode

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Solution Overview

Problem

Multithreaded processors face challenges in power management due to increased performance leading to higher power consumption, with existing techniques requiring sophisticated control schemes and significant information about processor state, and there is a need for a simple, automatic power conservation method with minimal performance penalty.

Innovation Solution

A bifurcated thread scheduler that automatically enters a default low power sleep mode when all threads are blocked, without issuing a wait instruction, and performs housekeeping functions before entering this mode, allowing for power conservation without degrading processor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multithreaded processors execute multiple threads concurrently to improve performance, then instructions per clock cycle increase, but power consumption increases

Engineering Contradiction:
Improveinstructions per clock cycleVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The processor periodically transitions between active multithreaded execution and low-power sleep mode based on thread blocking status. When all threads are blocked, the processor enters sleep mode periodically to conserve power, then resumes execution when threads become unblocked, creating a periodic on-off execution pattern that reduces average power consumption while maintaining productivity when needed

Inventive Principle:
Principle #19Periodic action

2Loss of energy

If sophisticated control schemes are used to manage power states, then power conservation improves, but device complexity increases

Engineering Contradiction:
Improvepower conservationVSAvoidcontrol scheme complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The thread scheduler automatically monitors thread blocking status and autonomously transitions the processor to low-power sleep mode without requiring external control signals or complex management logic. The scheduler serves itself by using its existing thread state information to make power management decisions, eliminating the need for separate sophisticated control schemes while achieving effective power conservation

Inventive Principle:
Principle #25Self-service

3Use of energy by moving object

If the processor enters low power mode when threads are blocked, then power consumption decreases, but execution time increases

Engineering Contradiction:
Improvepower consumptionVSAvoidexecution time
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The processor performs preliminary actions by maintaining thread state information and blocking status in the thread scheduler before entering low-power mode. This preliminary preparation allows the processor to quickly resume execution from the exact blocking point without losing thread context or requiring lengthy recovery sequences, thereby minimizing execution time loss while still achieving power savings during blocked states

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP1869536B1Multi-threaded processor comprising customisable bifurcated thread scheduler for automatic low power mode invocation
Publication Date: 2012.03.21 MIPS TECH INC
  • EP1869536B1 patent drawingFigure 1
  • EP1869536B1 patent drawingFigure 2
  • EP1869536B1 patent drawingFigure 3

AI summary

A processor comprises a processor core executing multiple threads. A bifurcated thread scheduler includes an internal processor core component and an external processor core component. The bifurcated thread scheduler identifies when all of the multiple threads are blocked and thereafter automatically enters a default low power sleep mode.