io_uring

ELI5 - The Vibe Check

io_uring is a modern Linux way of asking the kernel to do I/O work that skips almost all the usual back-and-forth. Instead of your program repeatedly interrupting the kernel with is it done yet, is it done yet, both sides just drop requests and results into a shared ring buffer that they both can see, no syscall needed for most operations, which is a big reason it dramatically outperforms the older epoll-based model for I/O-heavy workloads.

Real Talk

io_uring is a Linux kernel interface for asynchronous I/O that uses two shared ring buffers, a submission queue and a completion queue, memory-mapped between user space and the kernel, so applications can submit and retrieve I/O requests with drastically fewer syscalls and context switches than traditional read/write or epoll-based models. It supports a wide range of operations beyond networking, including file I/O, and underpins high-performance runtimes and databases that need to push I/O throughput to its limit.

Show Me The Code

// io_uring: submit a read, keep working, reap the result later
io_uring_prep_read(sqe, fd, buf, size, offset);
io_uring_submit(&ring);
// ... do other work ...
io_uring_wait_cqe(&ring, &cqe); // pick up the result whenever it's ready

When You'll Hear This

"We switched the proxy from epoll to io_uring and syscall overhead basically vanished." / "io_uring's shared ring buffers mean the kernel and your program barely have to talk."