Real-time scheduling with quality of service constraints

Whether or not the introduction of traffic classes improves upon the performance of ATM networks is discussed within the framework provided by a class of networks that guarantees quality of service. To provide a meaningful comparison the authors define the concept of a schedulable region, a region in the space of loads for which the quality of service is guaranteed. The authors show the dependence of the schedulable region on the scheduling algorithm employed, quality of service parameters, and traffic statistics. An efficient real-time scheduling algorithm is introduced that substantially increases the schedulable region without incurring prohibitive complexity costs. The schedulable region associated with this algorithm is compared with the ones generated by the static priority scheduling algorithm and a variant of the minimum laxity threshold algorithm. The size and shape of the schedulable region is explored by means of simulations