The Design and Implementation of a High-Performance Hybrid Memory File System

The emerging Non-Volatile Memory (NVM) connected to the memory bus provides opportunities for high-performance file accesses for its near-DRAM speed and byte-addressability. In this paper, a high-performance hybrid file system, called Hybrid Memory File System (HMFS), is designed and implemented to exploit the high speed of NVM and the large capacity of block devices. A file in HMFS can be stored across the NVM and block devices. In HMFS, each opened file is mapped to a contiguous virtual address space of the kernel. Using the related virtual address space, the physical locations of file data can be efficiently located by the hardware MMU or a dedicated page fault handler for HMFS. The file data in the NVM are accessed with high performance using the corresponding virtual addresses. The file data stored in the block devices are pre-fetched to take advantages of the NVM. Extensive experiments are conducted. The experimental results show that HMFS achieves significant performance improvement over EXT4 with a DRAM cache.