A NUMA-aware NVM File System Design for Manycore Server Applications

NOVA, a state-of-the-art NVM-based file system, is known to have scalability bottlenecks when multiple I/O threads read/write data simultaneously. Recent studies have identified the cause as the coarse-grained lock adopted by NOVA to provide consistency, and proposed fine-grained range-based locks to improve the scalability of NOVA. However, these variants of NOVA only scale on Uniform Memory Access (UMA) architecture and do not scale on Non-Uniform Memory Access (NUMA) architecture. This is because NOVA has no NUMA-aware memory allocation policy and still uses non-scalable file data structures. In this paper, we propose a NUMA-aware NOVA file system which virtualizes the NVM devices located across NUMA nodes so that they can be used as a single address space. The proposed file system adopts a local-first placement policy where file data and metadata are placed preferentially on the local NVM device to reduce the remote access problem. In addition, the lock-free per-core data structures proposed in this file system allow data to be updated concurrently while mitigating the remote memory access. Extensive evaluations show that our NUMA-aware NOVA for parallel writing is scalable with respect to the increased core count and outperforms vanilla NOVA by 2.56-19.18 times.