Multiprocessor Interrupt Allocation With Processor Affinity
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Solution Overview
Problem
In multiprocessor computing systems, efficiently allocating interrupts to processor cores is challenging due to the need to maintain processor-core affinity for interrupt service routines while balancing cache efficiency with the benefits of assigning execution to idle or lower-priority tasks, especially in scenarios with frequent interrupts or high-priority tasks.
Innovation Solution
The system determines a preferred processor core for executing an interrupt handler based on previous execution and communicates additional information to the interrupt controller to maintain processor-core affinity, allowing for efficient caching while considering idle or lower-priority processors for assignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the interrupt handler is assigned to the preferred processor core to maintain processor-core affinity, then cache efficiency is improved, but the system cannot utilize idle or lower-priority processors effectively
Solution Approach 1:
The interrupt allocation system dynamically adjusts processor assignment based on real-time processor states. The interrupt controller evaluates whether the preferred processor is idle, busy, or overloaded, and flexibly reassigns interrupts to alternative processors when beneficial, while maintaining affinity when advantageous. This dynamic approach resolves the contradiction by making the system adaptable to changing conditions rather than rigidly following a single allocation rule.
2Productivity
If the interrupt handler is assigned to an idle or lower-priority processor, then system resource utilization is improved, but cache efficiency deteriorates due to loss of processor-core affinity
Solution Approach 1:
The system changes the allocation parameter (processor assignment) based on the operational context. When the preferred processor is idle or overloaded, the system parameter changes to assign the interrupt to a different processor, maximizing resource utilization. When the preferred processor is available and affinity provides benefit, the parameter reverts to maintaining affinity. This conditional parameter adjustment resolves the contradiction between resource utilization and cache efficiency.
3Measurement precision
If additional information is communicated to the interrupt controller to maintain processor-core affinity, then interrupt handling precision is improved, but system complexity increases
Solution Approach 1:
The system performs preliminary action by pre-establishing processor-core affinity relationships and pre-identifying the preferred processor for each interrupt handler before interrupt occurrence. The interrupt controller maintains this affinity information in advance, allowing rapid, precise interrupt allocation decisions without complex real-time calculations. This preliminary preparation reduces the communication overhead and complexity during actual interrupt handling while maintaining high allocation precision.
Data Source
AI summary
Technologies are described herein for allocating interrupts within a multiprocessor computing system. Information communicated to an interrupt controller module can support allocating interrupt response resources so as to maintain processor affinity for interrupt service routines. This affinity can support caching efficiency by executing a specific interrupt handler on a processor that previously executed that interrupt handler. The caching efficiency may be balanced against the benefits of assigning execution of the interrupt hander to another processor that is currently idle or currently processing a lower priority task.