Optimizing Local File Accesses for FUSE-Based Distributed Storage

Modern distributed file systems can store huge amounts of information while retaining the benefits of high reliability and performance. Many of these systems are prototyped with FUSE, a popular framework for implementing user-level file systems. Unfortunately, when these systems are mounted on a client that uses FUSE, they suffer from I/O overhead caused by extra memory copies and context switches during local file access. Overhead imposed by FUSE on file systems is not small and becomes more pronounced during local file access. This overhead may significantly degrade the performance of data-intensive applications running with distributed file systems that aggressively use local storage. In this paper, we propose a mechanism that achieves rapid local file access in FUSE-based distributed file systems by reducing the number of memory copies and context switches. We then incorporate the mechanism into the FUSE framework and demonstrate its effectiveness through experiments, using the Gfarm distributed file system.