Title: SSP: Eliminating Redundant Writes in Failure-Atomic NVRAMs via Shadow Sub-Paging

Abstract:
Non-Volatile Random Access Memory (NVRAM) technologies are closing the performance gap between traditional storage and memory. However, the integrity of persistent data structures after an unclean shutdown remains a major concern. Logging is commonly used to ensure consistency of NVRAM systems, but it imposes significant performance overhead and causes additional wear out by writing extra data into NVRAM. Our goal is to eliminate the extra writes that are needed to achieve consistency. SSP (i) exploits a novel cache-line-level remapping mechanism to eliminate redundant data copies in NVRAM, (ii) minimizes the storage overheads using page consolidation and (iii) removes failure-atomicity overheads from the critical path, significantly improving the performance of NVRAM systems. Our evaluation results demonstrate that SSP reduces overall write traffic by up to 1.8×, reduces extra NVRAM writes in the critical path by up to 10× and improves transaction throughput by up to 1.6×, compared to a state-of-the-art logging design.