One year ago, the io_uring subsystem did
not exist in the mainline kernel; it showed up in the 5.1 release in May
2019. At its core, io_uring is a mechanism for performing asynchronous
I/O, but it has been steadily growing beyond that use case and adding new
capabilities. Herein we catch up with the current state of io_uring, where
it is headed, and an interesting question or two that will come up along
the way.

Source: LWN.net – [$] The rapid growth of io_uring