Interrupt Controller Timer Logic for Jitter Reduction
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Solution Overview
Problem
Existing data processing systems face challenges in managing interrupt response timing due to variations in processing unit instruction execution times, leading to jitter that affects the accuracy of real-time control calculations and constrains device performance, particularly in high-speed disk drives and automotive engine control systems.
Innovation Solution
A data processing apparatus with an interrupt controller and timer logic that generates a timing indication upon interrupt receipt, allowing the processing unit to control the interrupt response based on this indication, ensuring deterministic behavior by compensating for variations in interrupt handling times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processing unit executes instructions before handling interrupts, then instruction completion is ensured, but interrupt response timing varies significantly
Solution Approach 1:
The system performs preliminary actions by completing critical instruction sequences before checking for interrupts. The processor is designed to finish specific instruction groups (such as those that manually turn off interrupts) before the interrupt handling mechanism is activated, ensuring that these critical instructions are always completed while still allowing timely interrupt response.
2Reliability
If the interrupt controller prioritizes high priority interrupts, then high priority interrupt handling is improved, but lower priority interrupts experience delays
Solution Approach 1:
The interrupt handling system is segmented into multiple priority levels and distinct handling phases. The interrupt controller divides interrupt management into priority arbitration, queuing, and sequential service phases, allowing high priority interrupts to be handled immediately while lower priority interrupts are queued for subsequent handling without being completely blocked.
3Measurement precision
If instructions take longer to execute, then processing accuracy is improved, but interrupt response speed decreases
Solution Approach 1:
The system dynamically adjusts interrupt response behavior based on the current execution state. When complex instructions are being executed, the system dynamically manages interrupt masking and prioritization to allow critical interrupts to be handled at appropriate breakpoints, balancing the need for processing accuracy with interrupt response speed requirements.
Data Source
AI summary
A data processing apparatus and method for handling interrupts is provided, the apparatus having an interrupt controller operable to receive interrupts generated by a number of interrupt sources, and to determine based on predetermined criteria whether to output an interrupt request signal. A processing unit is provided which is operable upon receipt of the interrupt request signal to perform an interrupt service routine for a selected one of the received interrupts in order to generate an interrupt response for the corresponding interrupt source. Timer logic is also provided which is operable upon receipt of an interrupt generated by an associated interrupt source to produce a timing indication. As a result of this, the processing unit is operable, when performing the interrupt service routine for the interrupt generated by that associated interrupt source, to reference the timer logic in order to obtain the timing indication, and to control a predetermined aspect of the interrupt response in dependence on the timing indication. This has been found to provide a significantly improved technique for handling interrupts from interrupt sources which desire deterministic behavior with regards to the interrupt response.