LLLFS: A Low-latency Library File System for Persistent Memory

Abstract

Persistent memory (PM) is a promising storage medium for reducing file access latency, which is critical for modern applications. Unfortunately, traditional storage stacks designed for slow media significantly impair the low-latency access capability of PM. We propose LLLFS, a low-latency library file system for PM. Based on the observation that many modern applications access files under their directories exclusively, LLLFS stores both file data and metadata in a process-local file system on PM so that files are fully accessible in user space without system calls and synchronization. LLLFS keeps POSIX compatibility while allowing application-specific parameter tuning. Experimental results demonstrated that LLLFS outperformed conventional and PM-optimized file systems by 56.0% and 37.7%, respectively, in database update operations.