The Case for TUFs and UA Scheduling in RT UML Profile: A Real-Time Scheduling/Operating System Perspective

This position paper makes the case for incorporating time/utility functions (TUFs) and the paradigm of utility accrual real-time scheduling in the planned, updated version of the UML Profile for Schedulability, Performance, and Time. The case is made by arguing that the key underpinning of the current state-of-the real-time practice — the priority artifact — and that of the current state-of-the real-time art — deadline-based timeliness optimality — are grossly inadequate for specifying application timeliness objectives, for reasoning about timeliness behavior, and for performing resource management that can dependably satisfy timeliness objectives in many large-scale, dynamic real-time systems. We argue that TUFs and utility accrual scheduling provide a more generalized, adaptive, and flexible approach. Further, new research on utility accrual scheduling have significantly advanced the state-of-the-art of that paradigm. We survey these recent advances to provide the rationale for our case.