Write-Combined Logging: An Optimized Logging for Consistency in NVRAM

Abstract EN

Nonvolatile memory (e.g., Phase Change Memory) blurs the boundary between memory and storage and it could greatly facilitate the construction of in-memory durable data structures.

Data structures can be processed and stored directly in NVRAM.

To maintain the consistency of persistent data, logging is a widely adopted mechanism.

However, logging introduces write-twice overhead.

This paper introduces an optimized write-combined logging to reduce the writes to NVRAM log.

By leveraging the fast-read and byte-addressable features of NVRAM, we can perform a read-and-compare operation before writes and thus issue writes in a finer-grained way.

We tested our system on the benchmark suit STAMP which contains real-world applications.

Experiment results show that our system can reduce the writes to NVRAM by 33%–34%, which can help extend the lifetime of NVRAM and improve performance.

Averagely our system can improve performance by 7%–11%.