[dpdk-dev] [PATCH V2 1/5] ethdev: add new flow action for metering and policing

[Adrien Mazarguil]

On Thu, Oct 05, 2017 at 02:09:30PM +0100, Cristian Dumitrescu wrote:
> Metering and policing action typically sits on top of flow classification,
> which is why MTR objects are enabled through a newly introduced flow
> action.
> 
> The configuration of MTR objects is done in their own namespace (rte_mtr)
> within the librte_ether library. The MTR object is hooked into ethdev RX
> processing path using the "meter" flow action.
> 
> Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu at intel.com>

Looks good, one minor comment about the METER action semantics before acking
this patch, see below.

> ---
>  doc/guides/prog_guide/rte_flow.rst | 24 ++++++++++++++++++++++++
>  lib/librte_ether/rte_flow.h        | 22 ++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index 662a912..6b9cdc2 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -1354,6 +1354,30 @@ rule or if packets are not addressed to a VF in the first place.
>     | ``vf``       | VF ID to redirect packets to   |
>     +--------------+--------------------------------+
>  
> +Action: ``METER``
> +^^^^^^^^^^^^^^^^^
> +
> +Applies a stage of metering and policing.
> +
> +The metering and policing (MTR) object has to be first created using the
> +rte_mtr_create() API function. The ID of the MTR object is specified as
> +action parameter. One or several meter actions can be added to the same
> +flow. More than one flow can use the same MTR object through the meter
> +action. The MTR object can be further updated or queried using the
> +rte_mtr* API.

rte_flow is currently documented [1] as ignoring several actions of the same
kind in a given rule, in which case only the last one is taken into
account. It's a deliberate design choice to simplify implementation, which
I now think wasn't such a good idea after all.

I'm therefore not opposed to remove this restriction globally, however in
that case rte_flow documentation must be modified and PMDs reworked to
implement the new behavior (failing by default when encountering multiple
actions of the same time instead of ignoring them). It's probably a little
late to do this now though.

So my suggestion for the time being is to not describe what happens when
several MTR actions are provided. We'll keep this for the next overhaul of
rte_flow (some other changes are already planned).

[1] http://dpdk.org/doc/guides/prog_guide/rte_flow.html#actions

-- 
Adrien Mazarguil
6WIND