Directory-Granularity Filesystem Journaling for CMM-H SSDs

This conference talk presents DJFS (Journaling Filesystem with per-Directory Transaction), a novel approach to filesystem journaling that operates at directory granularity. Learn how researchers from KAIST, University of Wisconsin-Madison, and Samsung Electronics analyzed file access patterns across eight popular applications to discover that most file update operations center around associated directories. Explore the three key components of DJFS: path-based transaction selection, transaction coalescing, and transaction conflict resolution. Discover how per-directory journal transactions address fundamental journaling filesystem performance issues by reducing lock contention, transaction conflicts, transaction lock-up, and enabling parallel journal commits. See performance benchmarks showing DJFS improving throughput by 4.5× in Varmail, 2.5× in MDTest, and 3.7× in Exim compared to FastCommit, a state-of-the-art journaling filesystem.