FastCommit: resource-efficient, performant and cost-effective file system...
summary
Ext4 gains a hybrid journaling mode that replaces many fsync-triggered physical writes with compact logical records, so over 80% of commits fit in a single 4KB block, avoiding expensive cache flushes. Using compact logging, inline journaling and selective flushing cuts fsync latency ~57%, halves JBD2 throughput interference, reduces bytes and IOs to disk (up to ~56% fewer bytes), and speeds a mail-server run by ~33%; most code is merged upstream.
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chapters (20)
- 0:00FastCommit intro
- 0:44Journaling background
- 3:10Ext4 and jbd2 mechanics
- 4:55Fsync frequency overhead
- 7:05Journaling cost inefficiencies
- 7:27FastCommit overview
- 8:11Related work and positioning
- 9:38FastCommit design
- 10:44FastCommit fallback
- 11:27Fsync path in ext4 jbd2
- 12:07FastCommit optimizations
- 13:09Compact logging
- 14:34Fsync path optimization
- 15:41Latency profile vs jbd2
- 16:46Evaluation setup
- 17:30Workloads tested
- 18:14Resource efficiency
- 18:58Benchmark improvements
- 19:38NFS performance
- 20:01Conclusion and status
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