Global Versus Local Schedulability Analysis of a Two-Level Hierarchical System

Aircraft systems manage resource sharing among several uniprocessor modules operating under the ARINC 653 specification. This standard, based on a two-level hierarchical architecture, guarantees function isolation within partitions. Partitions are scheduled on the processor according to an infinitely repeated offline statically defined cycle. During each cycle, a partition may be accessed either once or multiple times. This study focuses on the case where each partition is granted a single processor access per cycle. We propose an approach that involves transforming a two-level hierarchical scheduling model into a conventional uni-level system. This transformation enables the application of existing results from non-hierarchical uniprocessor scheduling for analysis. We establish a correlation between the schedulability properties of both systems and derive an exact schedulability criterion for fully harmonic task sets. Additionally, we extend this approach to compute precise worst-case response times of tasks within a two-level hierarchical system, leveraging established uniprocessor schedulability results. Finally, we evaluate the scalability of this method.