An overview of interrupt accounting techniques for multiprocessor real-time systems

The importance of accounting for interrupts in multiprocessor real-time schedulability analsysis is discussed and three interrupt accounting methods, namely quantum-centric, task-centric, and processor-centric accounting, are analyzed and contrasted. Additionally, two special cases, dedicated interrupt handling (i.e., all interrupts are processed by one processor) and timer multiplexing (i.e., all jobs are released by a single hardware timer), are considered and corresponding analysis is derived. All discussed approaches are evaluated in terms of schedulability based on interrupt costs previously measured on a Sun Niagara multicore processor. The results show that there is no single “best” accounting technique that is always preferable, but rather that the relative performance of each approach varies significantly based on task set composition, i.e., the number of tasks and the maximum utilization.