An improved feasible shortest path real-time fault-tolerant scheduling algorithm

Fault tolerance is an important aspect of real-time computer systems, since timing constraints must not be violated. For real-time single processor environment, Ghosh proposed two queue-based scheduling techniques. an FSP (Feasible Shortest Path) algorithm and LTH(Linear lime Heuristics). Even though the FSP algorithm can produce optimal fault-tolerant schedules, it is not practical due to its time complexity The LTH algorithm is a greedy heuristics that closely approximates the optimal However since Ghosh's algorithm assumes that there is at most one fault within time interval df and does not consider interfault time it can deteriorate real-time scheduling performance due to unnecessary backup scheduling. In this paper; we have proposed an improved FSP algorithm on the more realistic assumption that there is no additional fault during minimum inter-fault time DeltaF after one fault occurs. The proposed algorithm can improve system performance by including more primary tasks in a fault-tolerant schedule and also reduce time complexity in generating backup schedules.