Hierarchical Interrupt Controller for Low Latency Task Switching
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Solution Overview
Problem
Conventional data processing systems, including operating systems and Real-Time Operating Systems, often exhibit unpredictable and high interrupt latencies, which limit their effectiveness, especially in embedded systems, due to arbitration and context switching overhead, and require significant memory and power consumption.
Innovation Solution
A multiplexed hierarchical array of interrupt controllers is used to enable low latency task switching by providing interrupt controller selection and task identification, offloading arbitration and context switching overhead from the processor, allowing for hardware scheduling without the need for an operating system or Real-Time Operating System.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional operating system or Real-Time Operating System is used to process interrupts and schedule tasks, then task switching can be managed through software control, but interrupt latency becomes unpredictable and high due to arbitration and context switching overhead
Solution Approach 1:
The patent replaces the software-based operating system with a hardware-based interrupt controller that performs task switching autonomously. The interrupt controller includes a task identifier and context switch logic that operates independently of the processor, eliminating software intervention and reducing latency. This substitution of mechanical/software control with hardware automation directly addresses the contradiction by making task switching both faster and more predictable.
Solution Approach 2:
The interrupt controller is designed to self-manage the task switching process without requiring processor involvement. It automatically identifies the next task, prepares context switches, and manages arbitration based on predefined priorities and identifiers. This self-service capability eliminates the overhead of software-based scheduling and reduces interrupt latency while maintaining reliable, predictable task switching behavior.
2Adaptability or versatility
If an operating system is used to manage task switching, then software control and scheduling flexibility are provided, but memory consumption and system complexity increase
Solution Approach 1:
The patent extracts the essential task switching functionality from the operating system and implements it as a dedicated hardware interrupt controller. By removing the software-based OS layer and retaining only the critical task management functions in hardware, the system reduces complexity while maintaining scheduling flexibility through hardware-defined task identifiers and priorities. This extraction principle directly resolves the contradiction by eliminating unnecessary software complexity while preserving adaptability.
3Productivity
If an operating system processes interrupts and schedules tasks, then comprehensive task management is achieved, but power consumption increases
Solution Approach 1:
The patent substitutes the power-intensive software operating system with a low-power hardware interrupt controller that performs task switching autonomously. The hardware controller consumes significantly less power than a full OS while maintaining comprehensive task management capability through dedicated task identifiers and priority-based arbitration logic. This substitution directly addresses the contradiction by reducing power consumption while preserving productivity.
Data Source
AI summary
A multiplexed hierarchical array of interrupt controllers is configured to enable low latency task switching of a processor. The hierarchical array comprises a plurality of interrupt controllers coupled to a root interrupt controller. For each task that the processor is configured to execute, a corresponding interrupt controller is provided. To switch the processor to a task, the corresponding interrupt controller signals the root interrupt controller which, in turn, sends an interrupt and a Task Identifier to the processor. The root interrupt controller also cooperates with an access multiplexer/demultiplexer to select the corresponding interrupt controller for communication with the processor. By providing interrupt controller selection as well as task identification, the hierarchical array offloads arbitration and context switching overhead from the processor. That is, in response to the interrupt, the processor switches to the identified task and may access a memory address space dedicated to the task.