Processor Idle Interrupt Coalescing for Longer Low-Power States
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Solution Overview
Problem
Maintaining a sufficient idle state in processors to realize power savings is difficult due to the sporadic and unpredictable nature of interrupts, which can prematurely wake the processor from low power states.
Innovation Solution
Implementing a control circuit that delays interrupts during processor idle states using delay timers, allowing the processor to remain in the idle state until a predetermined duration or priority-based delay tolerance is met, and resumes interrupts upon exiting the idle state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the processor enters idle state to reduce power consumption, then power savings are achieved, but the processor may be prematurely woken up by interrupts
Solution Approach 1:
The patent applies preliminary action by having the interrupt controller delay interrupt signals before they reach the processor. The controller pre-empts potential wake-up events by filtering out low-priority interrupts during the idle period, allowing the processor to remain in power-saving state longer without risk of premature interruption.
Solution Approach 2:
The interrupt controller serves as an intermediary between hardware interrupt sources and the processor. It mediates the interrupt traffic by selectively blocking or delaying interrupts during idle periods, acting as a buffer that protects the processor from immediate wake-up while still allowing necessary interrupt delivery when appropriate.
2Loss of energy
If interrupts are delayed during idle state to prolong idle duration, then power savings increase, but interrupt handling time is extended
Solution Approach 1:
The patent applies local quality by implementing different delay strategies for different interrupt priority levels. High-priority interrupts bypass the delay mechanism and are delivered immediately to the processor, while lower-priority interrupts are delayed during idle periods. This localized differentiation allows power savings without compromising critical real-time response requirements.
Solution Approach 2:
The interrupt delay mechanism is dynamic rather than static. The controller adjusts interrupt delivery timing based on the processor's operational state, transitioning between immediate delivery and delayed delivery modes. This dynamic behavior optimizes the balance between power consumption and interrupt response time in real-time.
3Duration of action of stationary object
If interrupt coalescing is implemented to reduce wake-ups, then idle state duration increases, but device complexity increases
Solution Approach 1:
The interrupt controller is designed with multi-functionality, serving both as a standard interrupt controller and as an idle-state protection mechanism. By integrating the coalescing functionality into the existing controller architecture, the patent avoids adding separate dedicated hardware blocks, thereby limiting the increase in device complexity while achieving extended idle state duration.
Data Source
AI summary
The disclosed device includes a processor that receives interrupts from one or more processor components, and a control circuit that can delay, in response to the processor entering an idle state, the processor component from sending interrupts to the processor. Various other methods, systems, and computer-readable media are also disclosed.