Interrupt Controller Logic for Reducing Processor Latency
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Solution Overview
Problem
Conventional interrupt control systems in computer systems experience high interrupt latency due to the time required for processors to switch from normal instruction routines to Interrupt Service Routines (ISRs), which can hinder efficient handling of asynchronous events from peripheral devices.
Innovation Solution
An interrupt control system with control logic that detects event signals and provides direct branch instructions to the processor, allowing it to bypass the normal instruction fetch process and directly execute the appropriate ISR, thereby reducing latency by prioritizing and processing interrupts more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the processor follows the conventional interrupt handling process (branching to predefined IRQ address, executing global interrupt handling routine, table-look-up to find ISR address), then the processor can handle interrupts with a complete and systematic approach, but the interrupt latency becomes high due to multiple instruction fetches and processing steps
Solution Approach 1:
The patent applies preliminary action by pre-storing interrupt service routine addresses in a lookup table within the interrupt controller. When an interrupt occurs, the controller directly provides the pre-prepared ISR address to the processor, eliminating the need for the processor to perform table-look-up and branch instruction execution. This advance preparation of interrupt handling paths significantly reduces interrupt latency.
Solution Approach 2:
The patent extracts the interrupt vector table and address translation functionality from the processor and places it in the interrupt controller. By moving this function to a dedicated controller component, the processor is relieved of the overhead associated with interrupt address resolution, allowing it to respond to interrupts more quickly while the controller handles the complex address mapping operations.
2Measurement precision
If the processor executes the global interrupt handling routine which includes accessing registers to interrogate the interrupt source and performing table-look-up to find the ISR address, then the processor can accurately identify and respond to the specific interrupt source, but the time required to start executing the ISR increases
Solution Approach 1:
The patent introduces an intermediary mechanism - the interrupt controller with its integrated lookup table - that sits between the interrupt sources and the processor. This intermediary performs the function of identifying the interrupt source and translating it to the corresponding ISR address, thereby maintaining accurate interrupt source identification while eliminating the time-consuming operations from the processor's critical path.
Solution Approach 2:
The interrupt controller performs preliminary action by pre-establishing the mapping between interrupt sources and ISR addresses in its lookup table. This pre-computed mapping allows the controller to directly provide the correct ISR address to the processor without requiring the processor to execute the global interrupt handling routine, thus maintaining identification accuracy while reducing response time.
Data Source
AI summary
An interrupt control system is disclosed. The interrupt control system can include control logic that provides at least one interrupt request signal to a processor in response to at least one event signal. The control logic provides at least one computer executable instruction to a processor in response to detecting an instruction request from the processor corresponding to an interrupt response.