> > 4. Direct NVMe queues - will there be interest in having io_uring > > managed NVMe queues? Sort of a new ring, for which I/O is destaged from > > io_uring SQE to NVMe SQE without having to go through intermediate > > constructs (i.e., bio/request). Hopefully,that can further amp up the > > efficiency of IO. > > This is interesting, and I've pondered something like that before too. I > think it's worth investigating and hacking up a prototype. I recently > had one user of IOPOLL assume that setting up a ring with IOPOLL would > automatically create a polled queue on the driver side and that is what > would be used for IO. And while that's not how it currently works, it > definitely does make sense and we could make some things faster like > that. It would also potentially easier enable cancelation referenced in > #1 above, if it's restricted to the queue(s) that the ring "owns". So I am looking at prototyping it, exclusively for the polled-io case. And for that, is there already a way to ensure that there are no concurrent submissions to this ring (set with IORING_SETUP_IOPOLL flag)? That will be the case generally (and submissions happen under uring_lock mutex), but submission may still get punted to io-wq worker(s) which do not take that mutex. So the original task and worker may get into doing concurrent submissions. The flag IORING_SETUP_SINGLE_ISSUER - is not for this case, or is it?
