Re: [RFC 0/2] ethdev: add new attribute for signature match

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

On Sun, May 14, 2017 at 03:50:04PM -0400, Qi Zhang wrote:
> We try to enable ixgbe's signature match with rte_flow, but didn't
> find a way with current APIs, so the RFC propose to add a new flow
> attribute "sig_match" to indicate if current flow is "perfect match"
> or "signature match"
> With perfect match (by default), if a packet does not match pattern,
> actions will not be taken. (this is identical with current behavior)
> With signature match, if a packet does not match pattern, it still
> has the possibility to trigger the actions, this happens when device
> think the signature of the pattern is matched.
> Signature match is expected to have better performance than perfect
> match with the cost of accuracy.
> When a flow rule with this attribute set, identical behavior can ONLY
> be guaranteed if packet matches the pattern, since different device
> may have different implementation of signature calculation algorithm.
> Driver of device that does not support signature match is not required to
> return error, but just simply igore this attribute, because the default
>  "perfect match" still can be regarded as a speical case of 
> "signature match".
> 
> Qi Zhang (2):
>   rte_flow: add attribute for signature match
>   doc/guides/prog_guide: add new rte_flow attribute
> 
>  app/test-pmd/cmdline_flow.c        | 11 +++++++++++
>  doc/guides/prog_guide/rte_flow.rst | 12 ++++++++++++
>  lib/librte_ether/rte_flow.h        |  3 ++-
>  3 files changed, 25 insertions(+), 1 deletion(-)

As discussed offline, modifying struct rte_flow_attr for this purpose is not
ideal. We've agreed that a new meta pattern item should be defined instead,
as described in the FDIR rules conversion section (8.9.7) of the
documentation [1].

[1] http://dpdk.org/doc/guides/prog_guide/rte_flow.html#fdir-to-most-item-types-queue-drop-passthru

-- 
Adrien Mazarguil
6WIND