Data Placement in Linux: Evolving Block and File I/O

on YouTube ↗45m

" summary

Flexible Data Placement (FDP) gives the host explicit placement IDs so Linux can map files/IO to device reclaim units, reducing garbage-collection overhead. Kernel pieces: io_uring passthrough (merged 5.19) and a 6.16 block IO with per-IO write stream path that propagates a 0–255 stream ID through bio→blk→NVMe. Real deployment in Meta's Cachelib shows a device with 8 streams keeps write amplification near 1 (vs >3 when lifetimes mix) and sharply improves P99 latency.

AI-written summary · about

" chapters (11)

1. 0:00Data placement in Linux
2. 1:02SSDs and data placement
3. 8:14SSD physical data placement
4. 11:07Garbage collection explained
5. 17:12Streaming to reduce writes
6. 20:06Flexible Data Placement (FDP)
7. 24:42Kernel support for FDP
8. 31:30Block I/O path in 6.16
9. 34:26File I/O and FDP challenges
10. 38:14FDP state and future
11. 39:17Q&A

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