Awesome, thanks for the info and your hard work Pavel! Cheers, Jesse ________________________________________ From: Pavel Begunkov <asml.silence@xxxxxxxxx> Sent: Tuesday, April 20, 2021 9:59 AM To: Jesse Hughes; io-uring@xxxxxxxxxxxxxxx Cc: John Subject: Re: Emulating epoll On 4/20/21 5:37 PM, Jesse Hughes wrote: > Hello, > > I want to start by saying thank-you for working on io_uring. My experience using it thus far has been great. > > I'm working on an open-source database product (KeyDB, a multi-threaded redis fork) and we're considering rewriting our IO to use io_uring. Our current implementation uses epoll, and processes IO on (mainly) sockets as they become ready. Wonderful, always interesting to learn about emerging use cases and new apps using it. > > If I'm understanding the literature correctly, to emulate epoll, we should be able to set up a uring, put in a read sqe for each incoming socket connection, then (using liburing) call io_uring_wait_sqe. Correct? Is there a better way of doing that? In general, the best way to do I/O is to issue a read/write/etc. sqe directly as you've mentioned. io_uring will take care of doing polling internally or finding a better way to execute it. However, to simply emulate epoll IORING_OP_POLL_ADD requests can be used There is support for multi-shot poll requests, which Jens added for coming linux 5.13 > > Our end-goal is not to emulate epoll, but that seems like the quickest way of getting something working that we can do further experiments with. > > For reference, if anyone's interested, our source repo is at : https://github.com/EQ-Alpha/KeyDB -- Pavel Begunkov
