Re: [dpdk-dev] [PATCH] doc: remove deprecated ethdev features

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Oct 15, 2019 at 9:26 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
>
> On 10/15/2019 3:16 PM, Jerin Jacob wrote:
> >>>>> @@ -36,13 +36,6 @@ VMDq                 =
> >>>>>   SR-IOV               =
> >>>>>   DCB                  =
> >>>>>   VLAN filter          =
> >>>>> -Ethertype filter     =
> >>>>> -N-tuple filter       =
> >>>>> -SYN filter           =
> >>>>> -Tunnel filter        =
> >>>>> -Flexible filter      =
> >>>>> -Hash filter          =
> >>>>> -Flow director        =
> >>>>>   Flow control         =
> >>>>>   Flow API             =
> >>>>>   Rate limitation      =
> >>>> I suggest adding these features back!
> >>>>
> >>>> "Flow director" and other filters are features that device/driver supports.
> >>>>
> >>>> And "Flow API" and "filter_ctrl" are methods used to implement these features.
> >>>> Indeed they are only different APIs to get input from application/user.
> >>>>
> >>>> It doesn't really mean much to say "Flow API" is supported? So what is really
> >>>> supported? It matters more what feature is supported.
> >>>>
> >>>> Since we are saying old method is deprecated, we can update the feature list of
> >>>> drivers which implements filtering features using old method as not supported.
> >>>> And that is the case with this patch since old APIs are marked as deprecated,
> >>>> users can't use them to enable a filtering feature.
> >>>>
> >>>> Indeed I am for removing the "Flow API" from feature list, first it is not a
> >>>> feature, second if it is only method to enable a filtering, and if filtering is
> >>>> enabled in a driver, what is the point of redundant "Flow API" listing?
> >>>>
> >>>> I can make a quick patch if there is no objection, thanks.
> >>>
> >>> As I understand it was a decision to avoid details about flow API support
> >>> in features matrix. Mainly because matrix would be really huge in
> >>> attempt to represent it. The question is why filters/patterns mentioned
> >>> above are better than others and should be mentioned.
> >>> I'm not against adding some details, just want to understand criteria.
> >>> Flexible and hash are definitely not well defined.
> >>> What is flow director and which features should be supported to say yes?
> >>>
> >
> >>
> >> The criteria I have is what users will be interested about a device/driver.
> >>
> >> Will it be really huge to list filtering capabilities of the devices? I believe
> >> we can group them into a few groups like above.
> >> Or at least keep existing one and improve it by time and +1 to clarify them more
> >> but that is something else.
> >>
> >> A device can have capabilities but it is not easy to find if that capability has
> >> been enabled via DPDK, this kind of feature matrix works for it, and all
> >> features together makes it much easier than digging datasheets and code.
> >>
> >> Saying that "Flow API" is enabled for a driver doesn't really gives any
> >> information to the user if they are interested what kind of filtering features
> >> are supported by that device/driver.
> >
> > I agree. I think, we need to enumerate rte flow patterns and actions
> > supported by the PMD.
> > Since there was no single place such documentation, we added the same
> > in PMD documentation
> > See 39.8. RTE Flow Support at https://doc.dpdk.org/guides/nics/octeontx2.html
> >
> > And IMO, We should not add deprecated features in the features matrix as
> > new PMDs are not planning to implement the deprecated APIs. That
> > makes, matrix looks
> > new PMDs do not implement a lot of features, but in reality, those are
> > deprecated and never planning to implement if even though HW supports it.
> >
>
> +1 to not add deprecated features to the matrix, but those removed ones [1] are
> not deprecated. Implementing them via "filter_ctrl" is deprecated. Below
> features still can be implemented via "Flow API", that is why I am for adding
> them back to default.ini.

Got it. Instead of [1], Can we document it as in the form of rte_flow
semantics(patterns and actions) so
that for the end-user it is very clear. Reason being:
# Expressing "Tunnel filter" or "N-tupe filter" or "Flexible filter"
or "Flow director" etc is very vague in rte_flow semantics
and function is not just limited with above-fixed functions
#  The new PMDs also can express the rte_flow aka "Flow API" support
in the rte_flow semantics.


> And announce them as supported per PMD only if they are implemented via Flow API.
>
> [1]
>  Ethertype filter     =
>  N-tuple filter       =
>  SYN filter           =
>  Tunnel filter        =
>  Flexible filter      =
>  Hash filter          =
>  Flow director        =