Energy management for real-time embedded applications with compiler support

Reducing device energy has become one of the most important challenges to embedded systems designers. Processors with dynamic voltage scaling permit trading performance for reduced energy consumption as a program executes. In this paper, we first present a novel hybrid scheme that uses dynamic voltage scaling to adjust the performance of embedded applications to reduce energy consumption while also meeting time constraints. Our fine-grained approach uses the compiler to insert power management hints in the application code. These hints convey path-specific runtime information about the program's progress to power management points invoked by the operating system that adjust processor performance. Second, we present an algorithm for inserting power management hints along different program paths. Finally, we experimentally evaluate our approach and show that significant energy reduction can be achieved. On two embedded applications, MPEG movie decoding and automatic target recognition, our scheme reduces energy by up to 79% over no power management and by up to 50% over static power management. We also experimentally demonstrate that our scheme achieves more energy savings compared to two purely compiler-directed schemes.