NapFS: A High-Performance NUMA-Aware PM File System

Persistent memory (PM) allows file systems to directly persist data on the memory bus. In order to expand the capacity of PM file system, building a file system across sockets with each attached PMs is attractive. However, accessing data across sockets incurs impacts of non-uniform memory access (NUMA) architecture, which degrade PM file system performance. In this paper, we first conduct experiments to understand the NUMA impacts on building PM file systems. We then propose four design principles for building a high-performance NUMA-aware PM file system NapFS. We architect NapFS with per-socket local PM file systems and per-socket dedicated IO thread pools. This not only allows applications to delegate data access to IO threads for avoiding remote PM access, but also fully reuses existing single-socket PM file systems to reduce implementation complexity. In addition, NapFS utilizes fast DRAM to accelerate performance by adding a global cache. We evaluate NapFS against other multi-socket PM file systems. The evaluation results show that NapFS achieves 2.2× and 1.0× throughput improvement for Filebench and RocksDB.