A Two-Class M/M/l System with Preemptive Non Real-Time Jobs and Prioritized Real-Time Jobs under Earliest-Deadline-First Policy

This paper introduces an analytical method for approximating the performance of a two-class priority m/m/l system. the prioritized class-1 jobs are real-time, served either with the preemptive or non-preemptive earliest-deadline-first (edf) policy and can preempt the non real-time class-2 jobs. the preempted service of the class-2 job is resumed from the time in instances where no class-1 job is in the system. the service discipline of class-2 jobs is fcfs. the required mean service times may depend on the class of the jobs. the real-time jobs have exponentially distributed relative deadlines until the end of service. the system is approximated by a markovian model in the long run, which can be solved numerically, using standard markovian solution techniques. the performance measures of the system are the loss probability of the class-1 jobs and the mean sojourn (waiting) time of the class-2 jobs. comparing numerical and simulation results, it is found that the existing errors are relatively small.