Runtime / Type
Auto
Select the best supported runtime at worker startup while retaining a safe platform fallback.
Configuration
[runtime]
type = "auto"
max_events = 1024
sq_entries = 4096
cq_entries = 8192
buf_ring_size = 16384
buf_size = 8192
All fields are optional after type. Readiness settings apply if epoll or kqueue is selected; queue and buffer settings apply if io_uring is selected.
Selection behavior
| Host | Result |
|---|---|
| Linux with required io_uring capabilities | io_uring |
| Linux without required capabilities | Epoll, with the fallback reason logged |
| macOS or BSD | Kqueue |
Linux probing checks required operations and provided-buffer registration. The decision is made once during worker startup.
Use auto when
- the same configuration is deployed across Linux and BSD-family systems;
- io_uring is preferred but not mandatory;
- graceful fallback is more important than enforcing one driver.
Auto must be explicit. Omitting [runtime] currently defaults to epoll.