On 5/30/24 10:02 AM, Bernd Schubert wrote: > > > On 5/30/24 17:36, Kent Overstreet wrote: >> On Wed, May 29, 2024 at 08:00:35PM +0200, Bernd Schubert wrote: >>> From: Bernd Schubert <bschubert@xxxxxxx> >>> >>> This adds support for uring communication between kernel and >>> userspace daemon using opcode the IORING_OP_URING_CMD. The basic >>> appraoch was taken from ublk. The patches are in RFC state, >>> some major changes are still to be expected. >>> >>> Motivation for these patches is all to increase fuse performance. >>> In fuse-over-io-uring requests avoid core switching (application >>> on core X, processing of fuse server on random core Y) and use >>> shared memory between kernel and userspace to transfer data. >>> Similar approaches have been taken by ZUFS and FUSE2, though >>> not over io-uring, but through ioctl IOs >> >> What specifically is it about io-uring that's helpful here? Besides the >> ringbuffer? >> >> So the original mess was that because we didn't have a generic >> ringbuffer, we had aio, tracing, and god knows what else all >> implementing their own special purpose ringbuffers (all with weird >> quirks of debatable or no usefulness). >> >> It seems to me that what fuse (and a lot of other things want) is just a >> clean simple easy to use generic ringbuffer for sending what-have-you >> back and forth between the kernel and userspace - in this case RPCs from >> the kernel to userspace. >> >> But instead, the solution seems to be just toss everything into a new >> giant subsystem? > > > Hmm, initially I had thought about writing my own ring buffer, but then > io-uring got IORING_OP_URING_CMD, which seems to have exactly what we > need? From interface point of view, io-uring seems easy to use here, > has everything we need and kind of the same thing is used for ublk - > what speaks against io-uring? And what other suggestion do you have? > > I guess the same concern would also apply to ublk_drv. > > Well, decoupling from io-uring might help to get for zero-copy, as there > doesn't seem to be an agreement with Mings approaches (sorry I'm only > silently following for now). If you have an interest in the zero copy, do chime in, it would certainly help get some closure on that feature. I don't think anyone disagrees it's a useful and needed feature, but there are different view points on how it's best solved. > From our side, a customer has pointed out security concerns for io-uring. That's just bs and fud these days. -- Jens Axboe
