Multi-core CPU Power Management via Staggered Idle Transitions
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Solution Overview
Problem
Existing CPU management methods fail to effectively address power supply noise, which affects CPU performance, particularly during transitions to and from idle states, due to complexities in implementing analog circuitry and software controls, especially for multi-core CPUs.
Innovation Solution
A power consumption management system that includes a power consumption estimation block and an activity control block to regulate CPU power consumption by adjusting clock frequency in small steps and managing transitions between CPU states, using digital logic to monitor CPU status and limit power supply transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If software control is used to manage CPU frequency during idle state transitions, then implementation complexity is reduced compared to analog circuitry, but the system cannot effectively handle all possible transition scenarios in multi-core CPUs
Solution Approach 1:
The patent segments the CPU idle state transition management into distinct states (first idle state with both cores inactive, second idle state with at least one core active) and uses separate timer mechanisms for each state. This segmentation allows the software to handle different transition scenarios systematically without requiring complex analog circuitry, resolving the contradiction between implementation simplicity and adaptability.
Solution Approach 2:
The patent implements preliminary actions by setting up timer interrupts before idle state transitions occur. The first timer interrupt is configured to detect when both cores are in the first idle state, and the second timer interrupt is configured for the second idle state. These pre-configured timers proactively manage frequency adjustments before power consumption spikes, enabling effective handling of multiple transition scenarios while maintaining software implementation simplicity.
2Speed
If CPU frequency is adjusted rapidly during idle state transitions, then response time is reduced, but power supply noise increases due to sharp current changes
Solution Approach 1:
The patent uses periodic timer interrupts to manage CPU frequency adjustments during idle state transitions. Instead of immediate rapid adjustment, the system uses periodic timing (first timer interrupt and second timer interrupt) to gradually transition between frequency states. This periodic action smooths out the current changes over time, reducing power supply noise while maintaining acceptable response time for state transitions.
3Use of energy by stationary object
If both CPU cores enter idle state simultaneously, then power consumption is reduced, but power supply transients increase due to coordinated shutdown requirements
Solution Approach 1:
The patent segments idle state management into two distinct states: first idle state where both cores are inactive but frequency is not yet reduced, and second idle state where frequency is reduced. The timer interrupts manage transitions between these states separately for each core, preventing simultaneous shutdown transients while still achieving coordinated power savings. This segmentation allows progressive power management that avoids transient spikes.
Solution Approach 2:
The patent implements preliminary frequency adjustment before actual core shutdown. The first timer interrupt detects when both cores are in the first idle state and triggers frequency reduction in advance. This preliminary action spreads out the power consumption reduction over time rather than occurring simultaneously with core shutdown, thereby reducing power supply transients while maintaining effective power savings.
Data Source
AI summary
A power consumption management system for a central processing unit may include a power consumption estimation block and an activity control block. The power consumption estimation block may be configured to estimate power consumption of the central processing unit based on information related to a status of the central processing unit. The activity control block may be configured to use the estimated power consumption to determine a control to be applied to the central processing unit for regulating a rate of change in power consumption of the central processing unit.