Re: [PATCH RFC bpf-next 0/7] Add bpf_link based TC-BPF API

On Mon, Jun 14, 2021 at 01:57:16AM IST, Jamal Hadi Salim wrote:

Hi,

Sorry - but i havent kept up with the discussion so some of this
and it is possible I may be misunderstanding some things you mention
in passing below (example that you only support da mode or the classid being
able to be handled differently etc).
XDP may not be the best model to follow since some things that exist
in the tc architecture(example ability to have multi-programs)
seem to be plumbed in later (mostly because the original design intent
for XDP was to make it simple and then deployment follow and more
features get added)

Integrating tc into libbpf is a definete bonus that allows with a
unified programmatic interface and a singular loading mechanism - but
it wasnt clear why we loose some features that tc provides; we have
them today with current tc based loading scheme. I certainly use the
non-da scheme because over time it became clear that complex
programs(not necessarily large code size) are a challenge with ebpf
and using existing tc actions is valuable.
Also, multiple priorities are  important for the same reason - you
can work around them in your singular ebpf program but sooner than
later you will run out "tricks".

Right, also I'm just posting so that the use cases I care about are clear, and
why they are not being fulifilled in some other way. How to do it is ofcourse up
to TC and BPF maintainers, which is why I'm still waiting on feedback from you,
Cong and others before posting the next version.

We do have this monthly tc meetup every second monday of the month.
Unfortunately it is short notice since the next one is monday 12pm
eastern time. Maybe you can show up and a high bandwidth discussion
(aka voice) would help?

That would be best, please let me know how to join tomorrow. There are a few
other things I was working on that I also want to discuss with this.

cheers,
jamal