The rapid growth of io_uring [LWN.net]

The rapid growth of io_uring

Posted Jan 26, 2020 21:49 UTC (Sun) by grober (guest, #136840)
Parent article: The rapid growth of io_uring

How io_uring implements asynchronous operations if everything is synchronous internally? Does it use thread pool?

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The rapid growth of io_uring

Posted Jan 27, 2020 0:23 UTC (Mon) by cesarb (subscriber, #6266) [Link] (1 responses)

Actually, everything is asynchronous internally. The kernel submits a request to the disk hardware, and some time later, the disk hardware interrupts the kernel to tell it's done. In the meantime, the CPU can be doing something else, be it running another thread or (with asynchronous I/O like io_uring) doing something else on the same thread.

The rapid growth of io_uring

Posted Jan 27, 2020 8:45 UTC (Mon) by dezgeg (guest, #92243) [Link]

Filesystem code is certainly synchronous for things like reading metadata (inodes) from disk.

The rapid growth of io_uring

Posted Jan 28, 2020 10:50 UTC (Tue) by jezuch (subscriber, #52988) [Link]

I was wondering about this too. Is it just a way to avoid the overhead of system calls, or is it actually, truly asynchronous?