Maximizing the system value while satisfying time and energy constraints

Embedded devices designed for various real-time applications typically have three constraints that must be addressed: energy, deadlines, and reward. These constraints play important roles in the next generation of embedded systems, since they provide users with a variety of quality-of-service (QoS) tradeoffs. We propose a QoS model in which applications may have several versions, each with different time and energy requirements, while providing different levels of accuracy (reward). An optimal scheme would allow the device to run the most critical and valuable versions of applications without depleting the energy source, while still meeting all deadlines. A solution is presented for frame-based and periodic task sets. Three algorithms are devised that closely approximate the optimal solution while taking only a fraction of the runtime of an optimal solution.