Reliability Driven Soft Real-Time Fuzzy Task Scheduling in Distributed Computing Environment

Abstract

All practical real-time scheduling algorithms in distributed systems present a trade-off between their computational complexity and performance. In real-time distributed systems, tasks have to be performed correctly, timely and most importantly in reliable manner. The research till date on task scheduling has primarily focused upon computation time, laxity, priority etc. Reliability of a task or task cluster is normally not considered, when it comes to task scheduling in distributed environment. Finding a reliable schedule in distributed systems with real-time constraints is shown to be NP-hard. The practical scheduling algorithms in real-time systems have not deterministic reliability. Deterministic reliable behavior is an important parameter for system robustness analysis. The intrinsic uncertainty in dynamic real-time systems increases the difficulties of scheduling problem. To alleviate these deficiencies, i have proposed a fuzzy scheduling approach to arrange real-time periodic and non-periodic tasks in systems considering reliability as the parameter for decision. In contrast, the approach balances task loads of the processors successfully while consider starvation prevention and fairness, which cause higher reliability tasks, have higher running probability. A simulation is conducted to evaluate the performance of the proposed approach. Experimental results have shown that the proposed fuzzy scheduler creates feasible schedules for homogeneous and heterogeneous tasks.