Enhancing lifetime of NVM-based main memory with bit shifting and flipping

Non-volatile memory (NVM) is considered as the most promising candidate of main memory due to many attractive properties, such as shock-resistivity, non-volatility, high density and near zero leakage power. However, the write endurance and high write energy consumption greatly limit its adoption in modern memory systems. In this paper, we propose a write reduction technique, called Min-Shift, to reduce the total number of writes to NVM. The basic idea is to re-encode the data to be written via bit shifting and flipping. This is motivated by the fact that NVM write operation takes more latency than read, and the energy cost of the value to be written varies a lot. The effectiveness of Min-Shift is verified by mathematical analysis and experiment. Experimental results show that the proposed technique can reduce the number of writes by 57.3% on average. The lifetime of NVM is 2.3× longer than before.