An SIMD-Accelerated Metadata Management Scheme for Persistent Memory File Systems

Persistent memory (PM) offers byte-addressable persistence with high random access performance close to DRAM. The special characteristics of PM have brought new opportunities and challenges to design file systems. Intuitively, file systems are IO-intensive and the computation overhead is negligible. Whereas, PM dramatically improves IO performance and we observe that the computation overhead of metadata operations in PM file systems is becoming increasingly non-negligible. Furthermore, with the heavy computation overhead in metadata operations, the CPU is easy to be saturated under a highly concurrent workload. Fortunately, due to abundant computation resources, SIMD technology provides potential opportunities to accelerate metadata operations for PM file systems. In this paper, we present an SIMD-accelerated metadata management scheme for PM file systems. Specifically, we design the SIMD-aware data structures and algorithms involved in metadata operations for PM file systems to accelerate metadata operations. In addition, to take the full performance of SIMD and leverage the compatibility of SIMD instructions and PM, we perform operations on PM directly to eliminate the overhead of data interaction between PM and DRAM. We implement a prototype called SPFS, and our evaluation demonstrates that SPFS can outperform other tested PM file systems in a variety of test scenarios.

I. Introduction

Persistent Memory (PM) is a new memory technology that was recently introduced by Intel [1]. PM offers byte-addressable persistence and high random access performance close to DRAM. Intel Optane DC persistent memory modules [2] are placed on the memory bus like DRAM and can be accessed via processor loads and stores. These special characteristics of PM have brought new opportunities and challenges to design file systems.