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

The real-time community is devoting considerable attention to flexible sche duling and adaptive systems. One popular means of increasing the flexibilit y, and hence effectiveness, of real-time systems is to use value-based sche duling. 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 disti nction is made between ordinal and cardinal value functions. Appropriate te chniques from utility theory are reviewed. An approach based on constant va lue modes is introduced and evaluated via a case example. (C) 2000 Elsevier Science B.V. All rights reserved.