[dpdk-dev] a doubt about rss types action in rte_flow

[Adrien Mazarguil]

Hi and sorry for the delay.

On Thu, Oct 18, 2018 at 06:42:52AM +0000, Peng, Yuan wrote:
> Hi Adrien,
> 
> I have a doubt about the action rss types in rte_flow.
> testpmd> flow create 0 ingress pattern end actions rss types end / end
> 
> what is the expected function of the command?
> Does it mean enable RSS in no types? So actually it can disable rss all?

Doing so requests whatever counts as default RSS from the driver as
documented in doc/guides/prog_guide/rte_flow.rst:

 "Unlike global RSS settings used by other DPDK APIs, unsetting the ``types``
  field does not disable RSS in a flow rule. Doing so instead requests safe
  unspecified "best-effort" settings from the underlying PMD, which depending
  on the flow rule, may result in anything ranging from empty (single queue)
  to all-inclusive RSS."

> There are different execution result of the command from our different NICs.
> Some NICs report error:
> Caught error type 2 (flow rule (handle)): Failed to create flow.: Invalid argument
> With some NICs, the command can be executed successfully, and disable rss function for all packet types.
> 
> Could you help to solve my questions?

PMDs must handle it as described by the documentation, 0 being the only safe
value applications can rely on regardless of device properties; applications
that just want traffic to be spread somehow among the queues they configured
instead of a single queue.

Therefore PMDs that currently reject it should be fixed.

-- 
Adrien Mazarguil
6WIND