A Fuzzy Algorithm For Scheduling Real Time Jobs in Multiprocessor Systems

In this paper we consider the use of fuzzy logic in the scheduling of periodic tasks in soft real-time multiprocessor systems. In real-time systems, tasks have to be performed correctly and timely. Finding minimal schedule in multiprocessor systems with real time constraints is shown to be NP hard. Most researches concerning real-time system scheduling assume scheduling constraint to be precise. However, in many circumstances the values of these parameters are vague. The vagueness of parameters suggests that we make use of fuzzy logic to decide in what order the requests should be executed to better utilize the system and as a result reduce the chance of a request being missed. The intrinsic uncertainty in dynamic real-time systems increases the difficulties of scheduling problem. Here a fuzzy approach to multiprocessor real-time scheduling is proposed in which the scheduling parameters are treated as fuzzy variables. A simulation is also performed and the results are judged against each other. Experimental results have shown that the proposed fuzzy scheduler creates feasible schedules for homogeneous and heterogeneous tasks. It also considers tasks priorities, which cause higher system utilization and lowers deadline miss time. According to the results, it performs very close to optimal schedule of uni-processor systems. It is concluded that the proposed fuzzy approach is very promising and it has the potential to be considered for future research.