WEnSIBR: Compression using dynamic bases supported with encoding and zone wise wear leveling for NVMs

Abstract

Non-Volatile Memories (NVM) are potential candidates to replace DRAM in main memory with a few intrinsic flaws associated with their writes, like poor endurance, excessive energy consumption, and long latency. Bit-flips due to costly write activities degrade the memory lifetime. We proposed SIBR, which compresses the incoming cacheblocks before writing in memory. Compressed blocks lead to lesser write activities in the memory cells. For further bit-flip reduction, we propose an extension of SIBR called EnSIBR that performs encoding on the SIBR-generated compressed blocks with relatively low storage overhead. However, only a small portion of memory, corresponding to the compressed block, is involved in write activity, leading to skewed bit-flip reception by memory cells.

Our second contribution is an intra-line wear-leveling method, which makes logical partitions of the memory lines called zones. We use the concept of age of a zone, which indicates the number of writes the zone has incurred over time. We also consider the number of bit-flips experienced by the zones with each write. The proposal, WEnSIBR, evens out the skewed distribution created by SIBR and EnSIBR. The novelty of WEnSIBR lies in its ability to uniformly distribute and simultaneously reduce bit-flips, which boosts the NVM lifetime significantly.