>"Our operating systems want to do things asynchronously, on their own terms. They'll tell you when they're done. Maybe this is a new era. Maybe making syscalls from 1970s Unix directly is like a remote procedure call to another machine - a leaky abstraction, a feeble attempt to impose your old mental model onto a new reality."

I think the article fell off here. Linux has a profoundly synchronous I/O system. The I/O U-Ring works there by dispatching requests to a kernel-maintained pool of worker threads. There the submitted request are run synchronously.

So the I/O U-Ring is in fact the abstraction, "a feeble attempt to impose your [new] mental model onto an [old] reality", as the author might put it. The actual Linux I/O system is most trivially exposed to userland by the same old "1970s Unix" means of the traditional system calls.

The real change with the I/O U-Ring is that it offers a way to submit work in bulk and finally introduces to Linux a form of I/O that appears to the program to be truly asynchronous.

(And it's not without some fair cause that file I/O is implemented as synchronous code. It's hard to do it asynchronously when it's a complex operation with many steps, where you are interacting with a page cache, not only for file contents but even caching the very metadata that describes how to get from an offset into a file to the block numbers where the data is stored. Windows has a famously profoundly asynchronous I/O system and even there actual file I/O is done just the same with synchronous logic ran in a worker thread, or copied directly from the cache if the requested data is already there.)