NVCL: Exploiting NVRAM in Cache-Line Granularity Differential Logging

Emerging byte-addressable non-volatile memory is considered an alternative storage device for persistence guarantee with high performance. In this work, we design NVCL (NVRAM Cache-Line Granularity Logging) and develop it in Redis. The proposed NVCL exploits the cache-line flush granularity of NVRAM to maintain the write-ahead differential log and is able to flush non-continuous dirty cache lines to guarantee persistence. NVCL effectively reduces the size of persistent logs by only flushing updated data in every memory page. We measured the performance on an Intel machine with a 16 GiB non-volatile dual in-line memory module (NVDIMM). Our performance study shows that NVCL can save up to 127× NVRAM writes and shows 84% speedup comparing to Redis append-only-file logging mechanism. NVCL also reduces up to 50% NVRAM writes and achieves 15% speedup over state-of-the-art logging mechanism NVWAL.