No abstract

We investigate a class of real-time control systems in which a variety of types of time constraints are imposed on computational activities. In addition, only a subset of critical activities must always meet the time constraints; other noncritical activities can violate time constraints within the allowable bounds; still others do not have time constraints. Also, the 'top level' system objectives, which determine the criticalness and time constraints of the execution of activities, can .be dynamically altered by the system operators or other subsystems. Therefore, specification and scheduling of workload must effectively incorporate the dynamic high-level system objectives and time constraints and reconcile these objectives with contention for limited system resomm.