Theory and Practice of EDF Scheduling in Distributed Real-Time Systems

The behavior of EDF schedulers has been very extensively studied for single-processor systems and there is also a lot of work on scheduling and schedulability analysis techniques dealing with EDF in homogeneous multiprocessor systems. However, if distributed systems are considered, only a small number of schedulability analysis techniques are available and there is only a little information on practical experience with this kind of systems. For distributed systems where a clock synchronization mechanism is not available, a recent work has theoretically shown how a feasible deadline assignment can significantly increase the utilization of processing resources while keeping the system schedulable (i.e., meeting all the timing requirements). On the other hand, Ada provides support for building applications scheduled by EDF. This paper proposes a set of experiments to contrast the theoretical results on scheduling deadline assignment in a distributed real-time application against those obtained through its real execution.