Your application must feel I/O bound. But in reality it must be syscall bound in order for io_uring to make any noticeable improvement.

In other words: if your application is already writing/reading at the max speed the hardware its on allows, you will see no improvement from this. That application is truly I/O bound.

An application that feels I/O bound will be doing lots and lots of little reads and writes and achieving low hardware utilization. That application is syscall bound rather than I/O bound, and io_uring will help tremendously.