On 4/20/21 6:48 PM, Jesse Hughes wrote: > Awesome, thanks for the info and your hard work Pavel! fwiw, there are also specialised send[msg],recv[msg] requests supported, not only read/write, see IORING_OP_* opcodes > > 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
