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In this paper, we consider timeliness and energy optimization in battery-powered, dynamic, embedded real-time systems, which must remain functional during an operation/mission with a bounded energy budget. We consider application activities that are subject to time/utility function time constraints, statistical assurance requirements on timeliness behavior, and an energy budget, which cannot be exceeded at run-time. To account for the inevitable variability in activity arrivals in dynamic systems, we describe arrival behaviors using the unimodal arbitrary arrival model (or UAM) [15]. For such a model, we present a DVS (dynamic voltage scaling)-based, CPU scheduling algorithm called Energy-Bounded Utility Accrual Algorithm (or EBUA). Since the scheduling problem is intractable, EBUA allocates CPU cycles, scales clock frequency, and heuristically computes schedules using statistical estimates of cycle demands, in polynomial-time. We analytically establish EBUA's properties including satisfaction of energy bounds, statistical assurances on individual activity timeliness behavior, optimal timeliness during under-loads, and bounded time for mutually exclusively accessing shared non-CPU resources. Our simulation experiments validate our analytical results and illustrate the algorithm's effectiveness and superiority over past algorithms.
Real-time systems, energy-efficient scheduling, time/utility functions, utility accrual scheduling

E. D. Jensen, H. Wu and B. Ravindran, "Utility Accrual Real-Time Scheduling Under the Unimodal Arbitrary Arrival Model with Energy Bounds," in IEEE Transactions on Computers, vol. 56, no. , pp. 1358-1371, 2007.
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