UMFS: An efficient user-space file system for non-volatile memory

摘要

Emerging non-volatile memory (NVM) is expected to be a mainstream storage media in embedded systems for its low-power consumption, near-DRAM speed, high density, and byte-addressability. In-memory file systems are proposed to achieve high-performance file accesses by storing files in NVM. Existing in-memory file systems, such as NOVA and EXT4-DAX, operate in kernel space and have additional overhead caused by kernel layers and mode change. In this paper, we propose a new design of User-space in-Memory File System (UMFS) to improve file access speed by minimizing the overhead of kernel. We implement UMFS in Linux system to verify the proposed design. Inopenoperation, UMFS exposes a file into user-space in constant time independent from the file size. Then, UMFS can achieve high-performance file accesses taking advantages of user virtual address space and existing address translation hardware in processors. We also propose an efficient user-space journaling to ensure data consistency while minimizing kernel cost. Extensive experiments are conducted on standard benchmarks to compare UMFS with NOVA, EXT4-DAX, and SIMFS, the state-of-the-art in-memory file system. The experimental results show that UMFS outperforms any of existing in-memory file systems.