Without DVS Device A

scaling (DVS [1]) is a popular technique in energy-aware systems: when a CPU is under-utilized, reduce its speed and voltage, thereby trading off increased execution times with reduced energy costs, while meeting real-time tasks ’ deadline constraints. However, DVS and other energy-saving techniques are ‘selfish ’ in nature, i.e., they are only concerned with reducing their local energy consumptions, disregarding the consequences their use may have on other devices. Consider two devices A and B, where A captures and compresses video images, sends them to B, where they will be decompressed, processed, and displayed. The latest point in time an image has to be received, processed, and displayed by B denotes an end-to-end deadline (E2E) Td. Figure 1 visualizes the problem: the shaded areas show periods of CPU activity (image processing), with the height of the area indicating the power costs, the arrows denote communications between devices, and the vertical line shows Td for a given image. When both A and B use DVS, their processing time