Dynamic Interrupt Controller for Multiprocessor Cache Locality
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Solution Overview
Problem
In multiprocessor systems, efficiently allocating interrupts to processor cores is challenging due to the need to balance between preempting high-priority tasks and utilizing idle or low-priority cores, while also considering cache locality to minimize latency and maximize efficiency.
Innovation Solution
An interrupt controller dynamically assigns interrupts based on a combination of processor core availability, priority levels, and cache locality scores, ensuring that interrupts are allocated to cores with cached resources and low priority tasks, thereby reducing the negative impact on current tasks and improving system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interrupts are allocated to processor cores based on availability and low priority tasks, then system productivity is improved, but task priority integrity may be compromised
Solution Approach 1:
The interrupt allocation strategy dynamically adjusts between priority-based and availability-based routing based on real-time system conditions. The controller monitors processor state and cache locality to make adaptive decisions, allowing the system to optimize productivity when conditions permit while maintaining priority integrity when needed.
Solution Approach 2:
The system changes the allocation parameters based on cache state information and processor availability. When a processor has cached resources for an interrupt handler, the system uses cache locality as a weighting factor to redirect interrupts, effectively changing the allocation criteria from strict priority to a hybrid model that balances priority with operational efficiency.
2Loss of time
If interrupts are allocated to processors with cached resources, then interrupt response latency is reduced, but processor core availability may be reduced
Solution Approach 1:
The system performs preliminary actions by maintaining cache state information about interrupt handlers and processor cores before interrupts occur. This allows the interrupt controller to pre-identify which processors have cached resources ready for potential interrupt handling, enabling faster allocation decisions when interrupts arrive without needing to check cache status at the moment of interruption.
Solution Approach 2:
The interrupt controller uses feedback from cache state monitoring to adjust interrupt allocation decisions. By continuously tracking which processors have cached resources for specific interrupt handlers, the system receives real-time feedback about optimal allocation targets and adjusts its routing decisions accordingly to minimize latency while managing processor workload.
3Adaptability or versatility
If dynamic interrupt scheduling is implemented, then system adaptability is improved, but device complexity increases
Solution Approach 1:
The interrupt controller segments the complex decision-making process into distinct functional components: it separately tracks processor availability state, monitors cache state information for interrupt handlers, and applies weighting factors based on priority and cache locality. This segmentation allows the complex adaptability to be managed through modular logic rather than a monolithic complex system.
Solution Approach 2:
The interrupt controller acts as an intermediary between the interrupt sources and processor cores, introducing a layer of intelligent mediation that translates diverse interrupt requests into optimized processor allocation decisions. This intermediary function handles the complexity by centralizing the decision logic and using cache state information as a key mediating factor in the allocation process.
Data Source
AI summary
Technologies are generally described herein for handling interrupts within a multiprocessor computing system. A priority level associated with a current task for each processor of the multiprocessor computing system can be maintained. Cache state information associated with each processor can also be maintained. Upon receiving an interrupt to the multiprocessor computing system, a cache locality score for each processor can be determined based on the maintained cache state information. A value can be computed that balances, for each processor, the priority level and the cache locality score. A processor for servicing the interrupt can be determined based on the computed value. The determined processor can be signaled to service the interrupt. Tracking state information related to processor cores can support rapid allocation of an arriving interrupt to a processor core without collecting processor core state information at interrupt time.