Enhancing Endurance of NVMs by Coarse To Fine Grained Write Reduction and Intra line Wear Leveling

Abstract

The unprecedented development in the processing speed of the Chip Multi-Processor (CMP) and the rise of modern data-intensive applications impose high pressure on the memory subsystem. It significantly increases the main memory footprint and necessitates designing of energy-efficient and newlinehigh capacity main memory. Unfortunately, the traditional memory systems, built predominantly using DRAM are not scalable to the low nanometer regime. At this need of the hour, the Emerging Non-Volatile Memories (NVMs) like PCM, STT-RAM, ReRAM offer fascinating features like high density and low leakage power that are useful for building high capacity and energy-efficient newlinememory systems. However, NVMs have asymmetric read/write operations, where writes are costly in terms of latency and energy. Also, frequent write operations to the NVM cells tend to wear out the memory cells, leading to a shortened memory lifetime. Furthermore, NVMs retain data even after the system is powered down. Hence, an attacker having physical access to the NVM DIMM can easily stream out the sensitive data stored in the NVM. Researchers have proposed encryption newlinetechniques to protect the sensitive NVM content. However, encryption algorithms lead to enormous bit-flips when the encrypted data is written in the NVM arrays. Hence, the lifetime issue of the NVM devices is further complicated by encryption-induced bit-flip spikes.