A spill data aware memory assignment technique for improving power consumption of multimedia memory systems

Abstract

As embedded memory technology evolves, the traditional Static Random Access Memory (SRAM) technology has reached the end of development. For deepening the manufacturing process technology, the next generation memory technology is highly required because of the exponentially increasing leakage current of SRAM. Non-volatile memories such as STT-MRAM (Spin Torque Transfer Magnetic Random Access Memory), PCM (Phase Change Memory) are good candidates for replacing SRAM technology in embedded memory systems. They have many advanced characteristics in the perspective of power consumption, leakage power, size (density) and latency. Nonetheless, nonvolatile memories have two major problems that hinder their use it the next-generation memory. First, the lifetime of the nonvolatile memory cell is limited by the number of write operations. Next, the write operation consumes more latency and power than the same size of the read operation. This study describes a compiler optimization technique to overcome such disadvantages of a nonvolatile memory component in hybrid cache memories. A hybrid cache is proposed to overcome the disadvantages using a compiler. Specifically, to minimize the number of write operations for nonvolatile memory, we present a data replacement technique that considers the locations of the register spill data. Many portions of the memory accesses are yielded by the spill data of a register allocator in an optimizing compiler. Such spill data can be partially removed using a recalculation method. Thus, we implemented an optimization technique that rearranges the data placement with recalculation to minimize the write instructions on the nonvolatile memory. Our experimental results show that the proposed technique can reduce the average number of spill codes by 20%, and improves the energy consumption by 20.2% on average.