netdev - Re: [PATCH RFC net-next 00/28 v2] Introducing P4TC

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Date: Fri, 2 Jun 2023 15:48:19 -0700
From: Marcelo Ricardo Leitner <mleitner@...hat.com>
To: Jamal Hadi Salim <jhs@...atatu.com>
Cc: netdev@...r.kernel.org, deb.chatterjee@...el.com, anjali.singhai@...el.com, 
	namrata.limaye@...el.com, jiri@...nulli.us, xiyou.wangcong@...il.com, 
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, 
	tom@...anda.io, p4tc-discussions@...devconf.info, vladbu@...dia.com, 
	simon.horman@...igine.com, khalidm@...dia.com, toke@...hat.com, 
	Mahesh.Shirshyad@....com, Vipin.Jain@....com, tomasz.osinski@...el.com, 
	mattyk@...dia.com, dan.daly@...el.com, john.andy.fingerhut@...el.com
Subject: Re: [PATCH RFC net-next 00/28 v2] Introducing P4TC

On Wed, May 17, 2023 at 07:02:25AM -0400, Jamal Hadi Salim wrote:
> We are seeking community feedback on P4TC patches.

This was the first time I read these patches. I don't have much to
comment on it overall yet.

>
> Apologies, I know this is a large number of patches but it is the best we could
> do so as not to miss the essence of the work.
> Please do note that > 50% of LOC are testcases. I should have emphasized
> this last time to improve the quality of the discussions, but mea culpa.

And much of the LOC that are not testcases, are for the CRUD
implementations. P4 is not simpe and allowing such simple
manipulations of all those types to the user comes at a cost and I
don't see a way around that.

The scripts seem long and complex, but they can be structured and are
human readable. I like how one is able to inspect the datapath no
matter how it was configured (from a p4 program or manually built).
This helps a lot with the supportability of solutions based on it.

One thing that I hate about u32 is that it is like perl^W^Wwrite-only.
It is as flexible as u32, but making sense out of those matches is a
nightmare. The approach here keeps the flexibility, while not
becoming as complex and slow moving as flower and yet, understandable
by humans. A promising in between the two extreme approaches that we
have in tc today.

  Marcelo