DPDK KNI vs io_uring

[Stephen Hemminger]

On Fri, 24 Jun 2022 20:32:19 +0000
Juan Pablo L. <jpablolorenzetti at hotmail.com> wrote:

> Hello folks, I am about to embark on the networking low level parts of my project,
> where I will be implementing a SCTP server for AAA for a 4G/5G telecom so I need to squeeze as much performance as possible .. I am looking at how to setup KNI and friends (unless anyone knows about a mature and robust SCTP stack in user space please let me know) ...

Mature and robust and open source SCTP seems unlikely. The closest you might get working is some of
the projects that ran FreeBSD network stack in userspace; but haven't heard about them in several years.

> 
> I have spent several days reading about io_uring, and I can see that accomplishes exactly the same role as the KNI module (or so I believe) with the advantage that is part of the kernel, etc etc.

No. io_uring is about bulk socket access; KNI is for pushing packets from DPDK into kernel.
Different API's different formats, different effect.

> 
> I have no experience with KNI or io_uring, so I will be starting from scratch with either one of them.
> 
> Has anyone had any experience with io_uring ? is it better, the same, worse than KNI ? any advice ?

io_uring is done by experienced kernel developers and merged into mainline kernel.
KNI is being deprecated and was never reviewed by the kernel community.

io_uring is driven of of socket send/recv.
KNI is based on dedicated kernel thread(s) doing polling.

> On a different note, I have read in the forums and mailing list that KNI is on its way out, that it will be deprecated sometime in the future, is my understanding correct ?
> If it is indeed the case, is anyone using anything as a KNI replacement ?
> 

There is documentation already on how to use virtio_user as better replacement for KNI.

If you want to use SCTP why are you so interested in DPDK.
It would be better to just use OS stack for that.