io_uring: Zero-Syscall I/O Architecture Revolution and Production Practice

io_uring was introduced by Jens Axboe in Linux 5.1 (2019), revolutionizing async I/O on Linux.

1. Traditional AIO Limitations

Linux native AIO only supports O_DIRECT file I/O, not networking.

2. io_uring Architecture

Shared SQ/CQ ring buffers enable zero-syscall submission.

3. Core Optimizations

Fixed Files/Buffers/Linked SQEs/Multishot.

4. SQPOLL

Kernel thread polls SQ for zero-syscall operation.

5. Code Example

Init queue, get SQE, prep_read, submit, wait complete.

6. Production Selection

io_uring as epoll replacement for high concurrency.