Cross-layer constrained power management: Application to a multimedia mobile platform

Power and resource management are key goals for the success of modern battery-supplied multimedia devices, which are complex systems with multiple functionalities all embedded in a small set of components. This kind of devices are usually based on SoCs with a wide range of subsystems, that compete in the usage of shared resources and offer several power saving capabilities, but need an adequate software support to exploit such capabilities. Therefore, offering the best QoS level and user experience, while saving as much power as possible to improve mobility becomes a challenging goal that involves all the layers of a system, from the application level to the device driver´s level. Moreover, reduced time to market in the development of new products require the definition of an agile methodology that permit portability of existing solutions and code across different devices and new products´ versions. The goal of CPM is to permit coordination and communication between different entities of the system to grant the desired QoS using dynamic optimization policies with negligible impact on the system. We focus on a real use case which shows the benefits of CPM both on resources management and on the solution of a dependency issue on the clock frequency of hardware devices (CPU and DSPs) in a SoC.