Re: io-uring and tcp sockets

[Stefan Metzmacher <metze@samba.org>]

[-- Attachment #1.1: Type: text/plain, Size: 1107 bytes --]

Hi David,

> New to io_uring but can't find this answer online, so reaching out.
> 
> I was trying out io_uring with netperf - tcp stream sockets - and
> noticed a submission is called complete even with a partial send
> (io_send(), ret < sr->len). Saving the offset of what succeeded (plus
> some other adjustments) and retrying the sqe again solves the problem.
> But the issue seems fundamental so wondering if is intentional?

I guess this is just the way it is currently.

For Samba I'd also like to be sure to never get short write to a socket.

There I'd like to keep the pipeline full by submitting as much sqe's as possible
(without waiting for completions on every single IORING_OP_SENDMSG/IORING_OP_SPLICE)
using IOSQE_IO_DRAIN or IOSQE_IO_LINK and maybe IOSQE_ASYNC or IORING_SETUP_SQPOLL.

But for now I just used a single sqe with IOSQE_ASYNC at a time.

Jens, do you see a way to overcome that limitation?

As far as I understand the situation is completely fixed now and
it's no possible to get short reads and writes for file io anymore, is that correct?

metze


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]