Minimizing write activities to non-volatile memory via scheduling and recomputation

Abstract

Non-volatile memories, such as flash memory, Phase Change Memory (PCM), and Magnetic Random Access Memory (MRAM), have many desirable characteristics for embedded DSP systems to employ them as main memory. These characteristics include low-cost, shock-resistivity, non-volatility, power-economy and high density. However, there are two common challenges we need to answer before we can apply non-volatile memory as main memory practically. First, non-volatile memory has limited write/erase cycles compared to DRAM. Second, a write operation is slower than a read operation on non-volatile memory. These two challenges can be answered by reducing the number of write activities on non-volatile main memory. In this paper, we propose two optimization techniques, write-aware scheduling and recomputation, to minimize write activities on non-volatile memory. With the proposed techniques, we can both speed up the completion time of programs and extend non-volatile memory's lifetime. The experimental results show that the proposed techniques can reduce the number of write activities on non-volatile memory by 55.71% on average. Thus, the lifetime of non-volatile memory is extend to 2.5 times as long as before on average. The completion time of programs can be reduced by 55.32% on systems with NOR flash memory and by 40.69% on systems with NAND flash memory on average.