On the schedulability analysis for distributed real-time systems

In distributed hard real-time systems, tasks not only have timing constraints but also often have precedence constraints caused by communication among them. In this paper a new schedulability analysis algorithm for distributed hard real-time systems is proposed in which both precedence constraints and communication costs are considered and represented by offsets and modified deadlines. To obtain a tight upper bound for the worst case response time, the concepts of local critical instant and local worst case response time are introduced. They are used to calculate global worst case response time in the system. The proposed schedulability analysis is compared with other schedulability analyses using test cases. The comparison shows that the proposed analysis is more accurate than the compared analyses. Copyright (C) 1999 IFAC.