The <a
href="https://man7.org/linux/man-pages/man7/io_uring.7.html">io_uring
subsystem</a> is all about asynchronous execution; applications count on it
to not block — unless explicitly requested to. Within io_uring, maintaining
the "never blocks" guarantee has sometimes been a challenge, given that
many paths in the kernel were never designed for asynchronous execution.
This problem has been worked around, but at a significant cost to
performance. Now, io_uring maintainer Jens Axboe has posted <a
href="https://lwn.net/ml/all/[email protected]">an RFC patch set</a>
with a somewhat radical (and potentially scary) solution to the problem.