Source code optimization and profiling of energy consumption in embedded systems

This paper presents a source code optimization methodology and a profiling tool that have been developed to help designers in optimizing software performance and energy in embedded sys-tems. Code optimizations are applied at three levels of abstrac-tion: algorithmic, data and instruction-level. The profiler ex-ploits a cycle-accurate energy consumption simulator [3] to relate the embedded system energy consumption and performance to the source code. Thus, it can be used for analysis (i.e., to find energy-critical sections of the code), and for validation (i.e., to assess the impact of each code optimization). Code optimizations and profiling tool are used to optimize and tune the implementation of an MPEG Layer III (MP3) audio de-coder for the SmartBadge [2] portable embedded system. We show that using our methodology and tool we can quickly and easily re-design the MP3 audio decoder software to run in real time with low energy consumption. Performance increase of 92 % and en-ergy consumption decrease of 77 % (over the original executable specification) has been achieved for MP3 audio decoding on the SmartBadge.