SPMFS: A Scalable Persistent Memory File System on Optane Persistent Memory

The first commercial Non-Volatile Memory (NVM) (i.e., Intel Optane DC Persistent Memory) exhibits limited parallelism, especially for write operations, which is generally neglected by existing NVM-aware file systems. Besides, the concurrent control of file systems also limits their scalability on high-performance NVMs under mainstream multi-core architectures. To effectively exploit full parallelism inherent in both NVMs and multi-core processors to enhance the overall performance, this paper proposes a novel scalable persistent memory file system, called SPMFS. SPMFS first partitions global metadata structures of the file system into per-core structures to distribute load and relieve contention. Second, SPMFS presents a fine-grained range lock to support concurrent accesses upon a file. Finally, SPMFS designs a dedicated I/O thread pool to offer optimal parallelism inherent in underlying NVM regardless of varying user-threads. We implement an SPMFS prototype and evaluate it under a variety of workloads generated by IOtest, Filebench, FIO, and production traces from Alibaba Pangu. The experiments show that SPMFS provides better scalability, and achieves up to 2.37 × write throughput improvement over state-of-the-art kernel NVM-aware file systems (Ext4-DAX, NOVA, and PMFS) and user-space file systems (Strata and Libnvmmio), without sacrificing the read performance.