Some Investigations on FCFS Scheduling in Hard Real Time Applications

We investigate some real time behaviour of a (discrete time) single server system with FCFS task scheduling. The main results deal with the probability distribution of a random variable SRD(T), which describes the time the system operates without violating a fixed task service time deadline T. The tree approach used for the derivation of our results is suitable for revisiting problems already solved by queueing theory, too . Relying on a simple general probability model, asymptotic formulas concerning all moments of SRD(T) are determined ; for example, the expectation of SRD(T) is proved to grow exponentially in T, i .e., E[SRD(T)] -C • k' for some x > 1 . © 1992 Academic Press, Inc.