Task Urgency-Based Clock Speed Management

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Solution Overview

Problem

Current power management systems in computing devices face challenges in balancing power consumption and responsiveness, particularly for urgent tasks, as they often rely on timers and idle states that can lead to latency issues and unpredictability in handling interrupts.

Innovation Solution

The system incorporates task urgency information to adjust clock speeds and idle states dynamically, rescheduling timer interrupts and measuring exit latencies to ensure timely processing of critical tasks while minimizing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the system uses timers and idle states to reduce power consumption, then energy efficiency is improved, but timer interrupt latency and responsiveness to urgent tasks deteriorate

Engineering Contradiction:
Improvepower consumptionVSAvoidtimer interrupt latency
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The system dynamically adjusts CPU frequency and idle state selection based on task urgency characteristics. The frequency management algorithm transitions between different operating points (frequency/voltage pairs) depending on whether tasks are background, normal, or real-time urgency, allowing optimal balance between power savings and responsiveness for each task type.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes physical parameters (CPU frequency, voltage, idle state depth) based on task urgency classification. By adjusting these parameters dynamically according to task characteristics, the system achieves aggressive power management for low-priority tasks while maintaining high responsiveness for urgent tasks.

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If the system reduces clock speed to minimize power consumption, then energy efficiency is improved, but responsiveness and correctness for urgent tasks deteriorate

Engineering Contradiction:
Improvepower consumptionVSAvoidresponsiveness for urgent tasks
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The system applies different quality levels of CPU performance to different tasks based on their urgency. High-urgency tasks receive full CPU frequency and priority handling, while low-urgency background tasks run at reduced frequencies, ensuring each task gets the appropriate level of service for its importance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The frequency management system dynamically adapts CPU operating parameters based on the mix of task urgencies present in the system. When real-time tasks are detected, the system transitions to higher frequency states; when only background tasks are present, it maintains lower frequency states for power savings.

Inventive Principle:
Principle #15Dynamics

3Use of energy by moving object

If the system uses aggressive idle states to reduce power consumption, then energy efficiency is improved, but unpredictability and latency in handling interrupts worsen

Engineering Contradiction:
Improvepower consumptionVSAvoidpredictability of interrupt handling
Core Design Contradiction:
Use of energy by moving objectVSEase of operation

Solution Approach 1:

The system performs preliminary classification of tasks by urgency before executing frequency management decisions. By identifying real-time tasks in advance and assigning them appropriate priority levels, the system ensures predictable interrupt handling while still allowing aggressive power management for non-critical tasks.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2771765B1System and method for managing clock speed based on task urgency
Publication Date: 2023.06.14 APPLE INC
  • EP2771765B1 patent drawingFigure 1
  • EP2771765B1 patent drawingFigure 2
  • EP2771765B1 patent drawingFigure 3

AI summary

A system and method are described for utilizing task urgency information when making power management decisions. For example, one embodiment of a method for managing power states of a processor comprises: executing a first power management state machine based on a first urgency level associated with a first task; detecting the execution of a second task having a second urgency level associated therewith; if the second urgency level is greater than the first urgency level, then executing a second power management state machine associated with the second urgency level.