A new async path on Linux
io uring is the modern Linux asynchronous IO interface. It centers on two ring buffers shared between your process and the kernel. The submission queue holds requests you want done, and the completion queue holds the results the kernel produces. Both live in memory mapped pages, so passing work needs no copying.
How it cuts syscalls
You fill several submission entries and then make a single io uring enter call to tell the kernel about all of them at once. The kernel processes them and posts results into the completion queue, which you read directly without any further call. With submission queue polling enabled, a kernel thread watches the ring and you can submit work with no system call at all.
- Batching many operations per enter call amortizes the syscall cost
- Shared rings avoid copying request and result structures across the boundary
- It supports networking, files, and even chained dependent operations
Why it matters
io uring brings true completion based asynchronous IO to Linux for both files and sockets, closing a long gap with Windows completion ports. It is a strong foundation for proactor style servers.
Key idea
io uring uses shared submission and completion rings so you batch many async operations per system call and read results straight from memory.