On 10/1/21 3:10 PM, Thomas Monjalon wrote: > 01/10/2021 12:15, Andrew Rybchenko: >> On 10/1/21 12:48 PM, Thomas Monjalon wrote: >>> 01/10/2021 10:55, Ivan Malov: >>>> On 01/10/2021 11:11, Thomas Monjalon wrote: >>>>> 01/10/2021 08:47, Andrew Rybchenko: >>>>>> On 9/30/21 10:30 PM, Ivan Malov wrote: >>>>>>> On 30/09/2021 19:18, Thomas Monjalon wrote: >>>>>>>> 23/09/2021 13:20, Ivan Malov: >>>>>>>>> Patch [1/5] of this series adds a generic API to let applications >>>>>>>>> negotiate delivery of Rx meta data during initialisation period. >>>>> >>>>> What is a metadata? >>>>> Do you mean RTE_FLOW_ITEM_TYPE_META and RTE_FLOW_ITEM_TYPE_MARK? >>>>> Metadata word could cover any field in the mbuf struct so it is vague. >>>> >>>> Metadata here is *any* additional information provided by the NIC for >>>> each received packet. For example, Rx flag, Rx mark, RSS hash, packet >>>> classification info, you name it. I'd like to stress out that the >>>> suggested API comes with flags each of which is crystal clear on what >>>> concrete kind of metadata it covers, eg. Rx mark. >>> >>> I missed the flags. >>> You mean these 3 flags? >> >> Yes >> >>> +/** The ethdev sees flagged packets if there are flows with action FLAG. */ >>> +#define RTE_ETH_RX_META_USER_FLAG (UINT64_C(1) << 0) >>> + >>> +/** The ethdev sees mark IDs in packets if there are flows with action >>> MARK. */ >>> +#define RTE_ETH_RX_META_USER_MARK (UINT64_C(1) << 1) >>> + >>> +/** The ethdev detects missed packets if there are "tunnel_set" flows in >>> use. */ >>> +#define RTE_ETH_RX_META_TUNNEL_ID (UINT64_C(1) << 2) >>> >>> It is not crystal clear because it does not reference the API, >>> like RTE_FLOW_ACTION_TYPE_MARK. >> >> Thanks, it is easy to fix. Please, note that there is no action >> for tunnel ID case. > > I don't understand the tunnel ID meta. > Is it an existing offload? API?
rte_flow_tunnel_*() API and "Tunneled traffic offload" in flow API documentation. > >>> And it covers a limited set of metadata. >> >> Yes which are not covered by offloads, packet classification >> etc. Anything else? >> >>> Do you intend to extend to all mbuf metadata? >> >> No. It should be discussed case-by-case separately. > > Ah, it makes the intent clearer. > Why not planning to do something truly generic? IMHO, it is generic enough for the purpose. > >>>>>>>>> This way, an application knows right from the start which parts >>>>>>>>> of Rx meta data won't be delivered. Hence, no necessity to try >>>>>>>>> inserting flows requesting such data and handle the failures. >>>>>>>> >>>>>>>> Sorry I don't understand the problem you want to solve. >>>>>>>> And sorry for not noticing earlier. >>>>>>> >>>>>>> No worries. *Some* PMDs do not enable delivery of, say, Rx mark with the >>>>>>> packets by default (for performance reasons). If the application tries >>>>>>> to insert a flow with action MARK, the PMD may not be able to enable >>>>>>> delivery of Rx mark without the need to re-start Rx sub-system. And >>>>>>> that's fraught with traffic disruption and similar bad consequences. In >>>>>>> order to address it, we need to let the application express its interest >>>>>>> in receiving mark with packets as early as possible. This way, the PMD >>>>>>> can enable Rx mark delivery in advance. And, as an additional benefit, >>>>>>> the application can learn *from the very beginning* whether it will be >>>>>>> possible to use the feature or not. If this API tells the application >>>>>>> that no mark delivery will be enabled, then the application can just >>>>>>> skip many unnecessary attempts to insert wittingly unsupported flows >>>>>>> during runtime. >>>>> >>>>> I'm puzzled, because we could have the same reasoning for any offload. >>>> >>>> We're not discussing *offloads*. An offload is when NIC *computes >>>> something* and *delivers* it. We are discussing precisely *delivery*. >>> >>> OK but still, there are a lot more mbuf metadata delivered. >> >> Yes, and some are not controlled yet early enough, and >> we do here. >> >>> >>>>> I don't understand why we are focusing on mark only >>>> >>>> We are not focusing on mark on purpose. It's just how our discussion >>>> goes. I chose mark (could've chosen flag or anything else) just to show >>>> you an example. >>>> >>>>> I would prefer we find a generic solution using the rte_flow API. > Can >>>>> we make rte_flow_validate() working before port start? >>>>> If validating a fake rule doesn't make sense, >>>>> why not having a new function accepting a single action as parameter? >>>> >>>> A noble idea, but if we feed the entire flow rule to the driver for >>>> validation, then the driver must not look specifically for actions FLAG >>>> or MARK in it (to enable or disable metadata delivery). This way, the >>>> driver is obliged to also validate match criteria, attributes, etc. And, >>>> if something is unsupported (say, some specific item), the driver will >>>> have to reject the rule as a whole thus leaving the application to join >>>> the dots itself. >>>> >>>> Say, you ask the driver to validate the following rule: >>>> pattern blah-blah-1 / blah-blah-2 / end action flag / end >>>> intending to check support for FLAG delivery. Suppose, the driver >>>> doesn't support pattern item "blah-blah-1". It will throw an error right >>>> after seeing this unsupported item and won't even go further to see the >>>> action FLAG. How can application know whether its request for FLAG was >>>> heard or not? >>> >>> No, I'm proposing a new function to validate the action alone, >>> without any match etc. >>> Example: >>> rte_flow_action_request(RTE_FLOW_ACTION_TYPE_MARK) Also, please, note that sometimes it makes sense to use action MARK on transfer level, match it in flow rules in non-transfer level, but do not require deliver the mark to host. >> >> When about tunnel ID? >> >> Also negotiation in terms of bitmask natively allows to >> provide everything required at once and it simplifies >> implementation in the driver. No dependency on order of >> checks etc. Also it allows to renegotiate without any >> extra API functions. > > You mean there is a single function call with all bits set? Yes, but not all, but required bits set. > >>>> And I'd not bind delivery of metadata to flow API. Consider the >>>> following example. We have a DPDK application sitting at the *host* and >>>> we have a *guest* with its *own* DPDK instance. The guest DPDK has asked >>>> the NIC (by virtue of flow API) to mark all outgoing packets. This >>>> packets reach the *host* DPDK. Say, the host application just wants to >>>> see the marked packets from the guest. Its own, (the host's) use of flow >>>> API is a don't care here. The host doesn't want to mark packets itself, >>>> it wants to see packets marked by the guest. >>> >>> It does not make sense to me. We are talking about a DPDK API. >>> My concern is to avoid redefining new flags >>> while we already have rte_flow actions. >> >> See above. >
