DHARMA: A tool for evaluating dynamic scheduling algorithms for real-time multiprocessor systems

A majority of today's real-time systems assume a priori knowledge of task characteristics and hence are based on static designs which contribute to their high cost and inflexibility. The next generation of hard real-time systems must be designed to be dynamic and flexible. This provides the motivation to study various dynamic scheduling proposals. In this paper, we evaluate new algorithms for scheduling and resource reclaiming in a dynamic multiprocessor system with fault-tolerant requirements. Resource reclaiming refers to the problem of utilizing resources left unused by a task when its actual computation time is less than its worst case computation time, or when a task is deleted in a fault-tolerant schedule. We also describe the design and implementation of a tool, called Dynamic (Heuristic) scheduling Algorithms for Real-time Multiprocessor systems (DHARMA), to study various dynamic scheduling algorithms, with or without fault-tolerance requirements, and associated resource reclaiming algorithms in a multiprocessor real-time system.