Optimal Stack Frame Placement and Transfer for Energy Reduction Targeting Embedded Processors with Scratch-Pad Memories

The 7th IEEE Workshop on Embedded Systems for Real-Time Multimedia : October 15, 2009 - October 16, 2009 : Grenoble, FranceMemory accesses are a major cause of energy consumption for embedded systems and the stack is a frequent target for data accesses. This paper presents a fully software technique which aims at reducing the energy consumption related to the stack by allocating and transferring frames or part of frames between a scratch-pad memory and the main memory. The technique utilizes an integer linear formulation of the problem in order to find at compile time the optimal management for the frames. The technique is also extended to integrate existing methods which deal with static memory objects and others which deal with recursive functions. Experimental results show that our technique effectively exploits an available scratch-pad memory space which is only one half of what the stack requires to reduce the stack-related energy consumption by more than 90% for several applications and on an average of 84% compared to the case where all the frames of the stack are placed into the main memory