Response-Time Analysis in Hierarchically-Scheduled Time-Partitioned Distributed Systems

Abstract

This paper develops an offset-based response-time analysis technique for analyzing complex distributed real-time systems where processing and communication resources use the time-partitioning strategy to isolate the operation of separate software components. Time partitioning may be provided in the processors by an ARINC 653 compliant operating system, and in the networks via the TTP communication protocol. The software components executed by the system may themselves be distributed and complex, composed of many concurrent tasks and with one or more end-to-end flows that may have end-to-end timing requirements. The developed analysis supports hierarchical scheduling where a primary scheduler performs time partitioning into separate partitions, and secondary fixed-priority schedulers dispatch the different concurrent tasks inside each partition. It also supports end-to-end flows that are either synchronized with the partition schedule or not. This is the first time that this kind of analysis is developed. An evaluation of an improvement introduced in the analysis is discussed. Two representative case studies are described.