hesela.devKyber I/O scheduler
Kyber is a Linux I/O scheduler that adjusts request-domain concurrency using measured latency and configured targets.
Mechanism: Device-wide tokens bound outstanding requests in each domain. In Linux v6.16, latency feedback changes domain depths, using device-I/O and total block-request latency distributions. A target is a control input, not a deadline for every request or an application latency guarantee. [1]
For requests handled by Kyber in v6.16, REQ_OP_WRITE selects the write domain regardless of the synchronous flag. Reserving request capacity for synchronous traffic is a separate mechanism. Neither classification establishes persistence after power loss. [1] [3]
Measurement scope: The v6.16 feedback loop uses histogram-bucket estimates of device-I/O p90 for congestion detection and total block-request p99 for depth adjustment. These populations are not application or fsync latency distributions. [1]
Relations
- related
- I/O scheduler, Linux blk-mq, Queue depth, Tail latency
Citations
- Linux v6.16: kyber-iosched.c, domain selection and latency feedback
- Linux 6.16: Kyber I/O scheduler tunables
- Linux 6.16: Explicit volatile write back cache control