Date:	Thu, 8 Jan 2015 19:03:20 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	John Fastabend <john.fastabend@...il.com>
Cc:	tgraf@...g.ch, sfeldma@...il.com, jhs@...atatu.com,
	simon.horman@...ronome.com, netdev@...r.kernel.org,
	davem@...emloft.net, andy@...yhouse.net
Subject: Re: [net-next PATCH v1 00/11] A flow API

Wed, Dec 31, 2014 at 08:45:19PM CET, john.fastabend@...il.com wrote:
>So... I could continue to mull over this and tweak bits and pieces
>here and there but I decided its best to get a wider group of folks
>looking at it and hopefulyl with any luck using it so here it is.
>
>This set creates a new netlink family and set of messages to configure
>flow tables in hardware. I tried to make the commit messages
>reasonably verbose at least in the flow_table patches.
>
>What we get at the end of this series is a working API to get device
>capabilities and program flows using the rocker switch.
>
>I created a user space tool 'flow' that I use to configure and query
>the devices it is posted here,
>
>	https://github.com/jrfastab/iprotue2-flow-tool
>
>For now it is a stand-alone tool but once the kernel bits get sorted
>out (I'm guessing there will need to be a few versions of this series
>to get it right) I would like to port it into the iproute2 package.
>This way we can keep all of our tooling in one package see 'bridge'
>for example.
>
>As far as testing, I've tested various combinations of tables and
>rules on the rocker switch and it seems to work. I have not tested
>100% of the rocker code paths though. It would be great to get some
>sort of automated framework around the API to do this. I don't
>think should gate the inclusion of the API though.
>
>I could use some help reviewing,
>
>  (a) error paths and netlink validation code paths
>
>  (b) Break down of structures vs netlink attributes. I
>      am trying to balance flexibility given by having
>      netlinnk TLV attributes vs conciseness. So some
>      things are passed as structures.
>
>  (c) are there any devices that have pipelines that we
>      can't represent with this API? It would be good to
>      know about these so we can design it in probably
>      in a future series.
>
>For some examples and maybe a bit more illustrative description I
>posted a quickly typed up set of notes on github io pages. Here we
>can show the description along with images produced by the flow tool
>showing the pipeline. Once we settle a bit more on the API we should
>probably do a clean up of this and other threads happening and commit
>something to the Documentation directory.
>
> http://jrfastab.github.io/jekyll/update/2014/12/21/flow-api.html
>
>Finally I have more patches to add support for creating and destroying
>tables. This allows users to define the pipeline at runtime rather
>than statically as rocker does now. After this set gets some traction
>I'll look at pushing them in a next round. However it likely requires
>adding another "world" to rocker. Another piece that I want to add is
>a description of the actions and metadata. This way user space can
>"learn" what an action is and how metadata interacts with the system.
>This work is under development.
>
>Thanks! Any comments/feedback always welcome.
>
>And also thanks to everyone who helped with this flow API so far. All
>the folks at Dusseldorf LPC, OVS summit Santa Clara, P4 authors for
>some inspiration, the collection of IETF FoRCES documents I mulled
>over, Netfilter workshop where I started to realize fixing ethtool
>was most likely not going to work, etc.
>
>---
>
>John Fastabend (11):
>      net: flow_table: create interface for hw match/action tables
>      net: flow_table: add flow, delete flow
>      net: flow_table: add apply action argument to tables
>      rocker: add pipeline model for rocker switch
>      net: rocker: add set flow rules
>      net: rocker: add group_id slices and drop explicit goto
>      net: rocker: add multicast path to bridging
>      net: rocker: add get flow API operation
>      net: rocker: add cookie to group acls and use flow_id to set cookie
>      net: rocker: have flow api calls set cookie value
>      net: rocker: implement delete flow routine

Truly impressive work John (including the "flow" tool, documentation).
Hat's off.

Currently, all is very userspace oriented and I understand the reason.
I also understand why Jamal is a bit nervous from that fact. I am as well..
Correct me if I'm wrong but this amount of "direct hw access" is
unprecedented. There have been kernel here to cover the hw differencies,
I wonder if there is any way to continue in this direction with flows...

What I would love to see in this initial patchset is "the internal user".
For example tc. The tc code could query the capabilities and decide what
"flows" to put into hw tables.

Jiri

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