[dpdk-dev] [PATCH] doc: update RSS action with best effort

[Andrew Rybchenko]

On 8/3/20 5:28 PM, Ori Kam wrote:
> Using the rte_flow action RSS types field,
> may result in an undefined outcome.
> 
> For example selecting both UDP and TCP,
> selecting TCP RSS type but the pattern is targeting UDP traffic.
> another option is that the PMD doesn't support all requested types.
> 
> Until now, it wasn't clear what will happen in such cases.
> This commit clarify this issue by stating that the PMD
> will work in the best-effort mode.
> 
> Signed-off-by: Ori Kam <orika at mellanox.com>
> ---
>  doc/guides/prog_guide/rte_flow.rst | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index 3e5cd1e..d000560 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -1735,6 +1735,16 @@ 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.
>  
> +Best effort will be used, in case there is a conflict inside the rule.
> +The conflict can be the result of:
> +
> +- Conflicting RSS types, for example setting both UDP and TCP.
> +
> +- Conflicting between RSS types and the requested pattern to match,
> +  for example matching on UDP and hashing RSS on TCP.

IMHO it is not a problem at all, but good to clarify anyway.

> +
> +- Hashing on types that are not supported by the PMD.

Shouldn't it return error to the caller?

> +
>  Note: RSS hash result is stored in the ``hash.rss`` mbuf field which
>  overlaps ``hash.fdir.lo``. Since `Action: MARK`_ sets the ``hash.fdir.hi``
>  field only, both can be requested simultaneously.
>