An Efficient DVS Algorithm for Pinwheel Task Schedules

In this paper, we focus on the pinwheel task model with a variable voltage processor with d discrete voltage/speed levels. We propose an intra-task DVS algorithm, which constructs a minimum energy schedule for k tasks in O(d+k log k) time. We also give an inter-task DVS algorithm with O(d+n log n) time, where n denotes th e number of jobs. Previous approaches solve this problem by generating a canonical schedule beforehand and adjusting the tasks’ speed in O(dn log n) or O(n) time. However, the length of a canonical schedule depends on the hyper period of those task periods and is of exponential length in general. In our approach, the tasks with arbitrary periods are first transformed into harmonic periods and then profile their key features. Afterward, an optimal discrete voltage schedule can be computed directly from those features. Keywords—Hard Real-time Systems, Power-aware Scheduling, Dynamic Voltage Scaling, Pinwheel Tasks