Hi all, Sorry for jumping in late,
> -----Original Message----- > From: Jerin Jacob <jerinjac...@gmail.com> > Sent: Wednesday, 1 February 2023 10:53 > > On Wed, Feb 1, 2023 at 12:46 PM Andrew Rybchenko > <andrew.rybche...@oktetlabs.ru> wrote: > > > > On 2/1/23 09:10, Ivan Malov wrote: > > > Hello everyone, > > > > > > Since making automatic, or implicit, offload decisions does > > > not belong in testpmd responsibility domain, it should be > > > safer to avoid calling the "negotiate metadata delivery" > > > API with some default selection unless the user asks to > > > do so explicitly, via internal CLI or app options. > > > > > > With that in mind, port config <port_id> ... sounds OK. > > > > > > PMDs that support flow primitives which can generate metadata > > > but, if in started state, can't enable its delivery may pass > > > appropriate rte_error messages to the user suggesting > > > they enable delivery of such metadata from NIC to PMD > > > first. This way, if the person operating testpmd > > > enters a flow create command and that fails, > > > they can figure out the inconsistency, stop > > > the port, negotiate, start and try again. > > > > > > As for non-debug applications, their developers shall > > > be properly informed about the problem of enabling > > > delivery of metadata from NIC to PMD. This way, > > > they will invoke the negotiate API by default > > > in their apps, with the feature selection (eg. > > > MARK) as per nature of the app's business. > > > > > > This API should indeed be helpful to some PMDs with > > > regard to collecting upfront knowledge like this. > > > At the same time, should be benign to those PMDs > > > who do not need this knowledge and can enable > > > delivery of metadata right when inserting the > > > flow rules. So I hope the API does not create > > > too much discomfort to vendors not needing it. > > > > > > Thank you. > > > > > > On Wed, 1 Feb 2023, Thomas Monjalon wrote: > > > > > >> 31/01/2023 17:17, Jerin Jacob: > > >>> On Fri, Jan 27, 2023 at 8:31 PM Thomas Monjalon > <tho...@monjalon.net> > > >>> wrote: > > >>>> > > >>>> 27/01/2023 11:42, Nithin Kumar Dabilpuram: > > >>>>> From: Thomas Monjalon <tho...@monjalon.net> > > >>>>>> 27/01/2023 06:02, Nithin Kumar Dabilpuram: > > >>>>>>> From: Thomas Monjalon <tho...@monjalon.net> > > >>>>>>>> Ferruh is proposing to have a command "port config <port_id> > ..." > > >>>>>>>> to configure the flags to negotiate. > > >>>>>>>> Are you OK with this approach? > > >>>>>>> > > >>>>>>> Yes, we are fine to have such command to enable and disable the > > >>>>>>> feature > > >>>>>>> with default being it disabled if supported by PMD. > > >>>>>>> Is default being disabled fine if the feature is supported by a > > >>>>>>> PMD ? > > >>>>>> > > >>>>>> I think the default should be enabled for ease of use. > > >>>>> > > >>>>> Since testpmd is used extensively for benchmarking purposes, we > > >>>>> thought it should have minimum features > > >>>>> enabled by default. The default testpmd doesn't have any Rx/Tx > > >>>>> offloads enabled(except for FAST FREE), default > > >>>>> fwd mode being "iofwd" and the Rx metadata is only referenced > when > > >>>>> dumping packets. > > >>>>> > > >>>>> > > >>>>>> Do we have similar features disables by default? > > >>>>>> I mean do we know features in testpmd which require a "double > > >>>>>> enablement" > > >>>>>> like one configuration command + one rte_flow rule? > > >>>>> > > >>>>> Spec itself is that way i.e "RTE_FLOW_RULE + > > >>>>> RX_METADATA_NEGOTIATE(once)" > > >>>>> > > >>>>> Isn't it enough if > > >>>>> > > >>>>> #1 We have enough print when rte_flow is being create without > > >>>>> negotiation done and ask user to enable rx metadata using > > >>>>> "port config <port_id>..." > > >>>>> #2 Provide testpmd app arg to enable Rx metadata(for example " > > >>>>> --rx-metadata") like other features to avoid calling another > > >>>>> command before rte flow create. > > >>>> > > >>>> I'm not sure what is best. > > >>>> I will let others discuss this part. > > >>> > > >>> IMO, enabling something always defeat the purpose to negotiate. IMO, > > >>> someone needs to negotiate > > >>> for a feature if the feature is needed. I think, the double enablement > > >>> is part of the spec itself. In case, The PMD > > >>> drivers won't like double enablement, no need to implement the PMD > > >>> callback. That way, there is no change in the existing flow. > > >>> > > >>> The reason why cnxk driver thought of leveraging negotiate() feature > > >>> so that it helps for optimization. e.s.p > > >>> function template for multiprocess case as we know what features > > >>> needed in fastpath upfront. > > >>> > > >>> If there still concerns with patch we can take up this to TB decide > > >>> one way or another to make forward progress. Let us know. > > >> > > >> Ferruh, Andrew, Ori, Ivan, what is your opinion? > > >> Let's progress with this patch to make it in -rc1. > > > > As I understand all agreed that we need testpmd command to > > control negotiated Rx metadata. May be even command-line > > option would be useful. > > > > So, remaining question is what should be the default value in > > testpmd. Note that it is just testpmd question since default > > value in an abstract application is nothing negotiated > > (if I'm not mistaken). > > > > The key advantaan ge of the current behaviour is to avoid > > "double-enabling" in testpmd. It preserves behaviour which > > we had before before the API addition. It is a strong > > argument. Basically it puts the feature into the same > > basket as FAST_FREE - need an action to run faster. > > I think, there is a disconnect here. FAST_FREE is enabled by default. > i.e We don't need any specific action to run faster. To align with performance > test application, by default the configuration should be run faster. User > needs to give explicit configuration to allow more offload or the one causes > the mpps drops. IMO, That is the theme followed in testpmd. > > I agree with Andrew, the default should stay the same, as now, PMD may already implement logic to only enable the feature if there is a flow rule. Changing the default will result in breaking applications. I want to suggest new approach for this feature, maybe we can use the rte_flow_configure, and add a new bit that says if those actions are going to be used. What do you think? > > I see no problem in such approach. > > > > The key disadvantage is the difference in testpmd and > > other applications default behaviour. > > > > I'd look at the feature in the following way: > > if an application theoretically wants to use > > USER_FLAG, USER_MARK or TUNNEL_ID it must negotiate > > corresponding Rx metadata to ensure that the feature is > > available and HW is informed that application may need it. > > Since testpmd supports corresponding flow API actions and > > flow tunnels, it tries to negotiate it by default, but do > > not fail if the negotiation fails. > > > > So, I'd would vote to keeping the default value as is. > >
