hesela.deviJournaling
iJournaling is a research ext4 journaling design that commits file-related metadata on fsync while retaining periodic compound transactions.
Separate per-core journals reduce unrelated commit dependencies; recovery reconstructs shared metadata. Directory fsync and uncommitted hard-link changes use normal journaling. [1]
FastCommit's ATC 2024 comparison questions compatibility with applications relying on incidental persistence of other files. It did not benchmark iJournaling because the code was unavailable to its authors. [2]
The Linux fsync contract concerns the referenced file, not every previously modified file; directory-entry durability requires separate attention. [3]
The FAST 2025 DJFS study later evaluated an iJournaling port over CXL.mem on a CMM-H prototype, not the unchanged 2017 implementation. Code unavailable to one study's authors is a time-scoped statement, not proof of permanent unavailability. [4]
Relations
- related
- Ext4 fast commit, Physical journaling
Citations
- Park and Shin. iJournaling. USENIX ATC 2017, pp.787-798; sections 5.1-5.3 and 6.4.
- Shirwadkar, Kadekodi and Tso. FastCommit. USENIX ATC 2024, section 3 and section 4 footnote 4, pp.159-160.
- Linux man-pages 6.19: fsync(2), file and directory synchronization.
- Yoo et al. DJFS: Directory-Granularity Filesystem Journaling for CMM-H SSDs. FAST 2025, section 7.1, printed p.45.
Sources & caveats
- Historical source synthesis, not a prototype execution, performance replication or claim of stock-kernel support.
- The companion article compares published block-count descriptions without treating the proposed single-block optimization as measured.