The meaning and role of value in scheduling flexible real-time systems

The real-time community is devoting considerable attention to flexible scheduling and adaptive systems. One popular means of increasing the flexibility, and hence effectiveness, of real-time systems is to use value-based scheduling. It is surprising however, how little attention has been devoted, in the scheduling field, to the actual assignment of value. This paper deals with value assignment and presents a framework for undertaking value-based scheduling and advises on the different methods that are available. A distinction is made between ordinal and cardinal value functions. Appropriate techniques from utility theory are reviewed. An approach based on constant value modes is introduced and evaluated via a case example.