-----Original Message-----
> Date: Tue, 5 Jun 2018 14:54:58 +0530
> From: "Rao, Nikhil" <nikhil....@intel.com>
> To: Jerin Jacob <jerin.ja...@caviumnetworks.com>
> CC: hemant.agra...@nxp.com, dev@dpdk.org, narender.vang...@intel.com,
> abhinandan.guj...@intel.com, gage.e...@intel.com, nikhil....@intel.com
> Subject: Re: [RFC] eventdev: event tx adapter APIs
> User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
> Thunderbird/52.8.0
>
> On 6/4/2018 10:41 AM, Jerin Jacob wrote:
> > -----Original Message-----
> > > Date: Fri, 1 Jun 2018 23:47:00 +0530
> > > From: "Rao, Nikhil" <nikhil....@intel.com>
> > > To: Jerin Jacob <jerin.ja...@caviumnetworks.com>
> > > CC: hemant.agra...@nxp.com, dev@dpdk.org, narender.vang...@intel.com,
> > > abhinandan.guj...@intel.com, gage.e...@intel.com, nikhil....@intel.com
> > > Subject: Re: [RFC] eventdev: event tx adapter APIs
> > > User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
> > > Thunderbird/52.8.0
> > >
> > >
> > > Hi Jerin,
> >
> >
> > > The workers invoke rte_event_enqueue_burst() to their local port not to
> > > the
> > > extra port as you described. The queue ID specified when
> > > enqueuing is linked to the the adapter's port, the adapter reads these
> > > events and transmits mbufs on the
> > > ethernet port and queue specified in these mbufs. The diagram below
> > > illustrates what I just described.
> > >
> > > +------+
> > > | | +----+
> > > |Worker+-->+port+--+
> > > | | +----+ | +----+
> > > +------+ | +-->+eth0|
> > > | +---------+ +-------+ | +----+
> > > +--+ | +----+ | +---+ +----+
> > > | Queue +-->+port+-->+Adapter|------>+eth1|
> > > +--+ | +----+ | +---+ +----+
> > > +------+ | +---------+ +-------+ | +----+
> > > | | +----+ | +-->+eth2|
> > > |Worker+-->+port+--+ +----+
> > > | | +----+
> > > +------+
> >
> >
> > Makes sense. One suggestion here, Since we have ALL type queue and
> > normal queues, Can we move the queue change or sched_type change code
> > from the application and move that down to function pointer abstraction(any
> > way adapter knows which queues to enqueue for), that way we can have same
> > final stage code for ALL type queues and Normal queues.
> >
> Yes, I see the queue/sched type change approach followed in
> pipeline_worker_tx.c, a queue id can be provided in
> rte_event_eth_tx_adapter_conf
>
> +struct rte_event_eth_tx_adapter_conf {
> + uint8_t event_port_id;
> + /**< Event port identifier, the adapter dequeues mbuf events from this
> + * port.
> + */
> + uint16_t tx_metadata_off;
> + /**< Offset of struct rte_event_eth_tx_adapter_meta in the private
> + * area of the mbuf
> + */
> + uint32_t max_nb_tx;
> + /**< The adapter can return early if it has processed at least
> + * max_nb_tx mbufs. This isn't treated as a requirement; batching may
> + * cause the adapter to process more than max_nb_tx mbufs.
> + */
> +};
>
> </sniped>
>
> > > The worker core will receive events pointing to mbufs that need to be
> > > transmitted to different
> > > ports/queues, as described above. The port and the queue will be populated
> > > in the mbuf and the
> > > API can be as below
> > >
> > > uint16_t rte_event_eth_tx_adapter_enqueue(uint8_t instance_id, uint8_t
> > > event_port_id, const struct rte_event ev[], uint16_t nb_events);
> > >
> > > Let me know if that works for you.
> >
> > Yes. That API works for me. I think, we can leverage "struct
> > rte_eventdev" area for adding new function pointer. Just like
> > enqueue_new_burst, enqueue_forward_burst variants, we can add one more
> > there, so that we can reuse that hot cacheline for all fastpath function
> > pointer case.
> > That would translate to adding "uint8_t dev_id" on the above API.
> The dev_id can be derived from the instance_id, does that work ?
Do we need to that in fastpath?, IMO, if you can do that in slow path then it
is fine.
>
> I need some clarification on the configuration API/flow. The
> eventdev_pipeline sample app checks if DEV_TX_OFFLOAD_MT_LOCKFREE flag is
> set on all ethernet devices and if so, uses the pipeline_worker_tx path as
> opposed to the "consumer" function,
Yes
> if we were to use the adapter to replace
> some of the sample code then it seems like the
> RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT is hardware assist for the
> pipeline worker tx mode, the adapter would support 2 modes (consumer and
> worker_tx, borrowing terminology from the sample), worker_tx would only be
> supported if the eventdev supports
> RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT (at least in the first version)
Yes.
1) I think, rte_event_eth_tx_adapter_enqueue() function can simply call,
struct rte_eventdev *dev = &rte_eventdevs[dev_id];
return (*dev->eth_tx_adapter_enqueue)(...);
2) You can expose generic version of "eth_tx_adapter_enqueue" in Tx
adapter. If drivers does not set the "eth_tx_adapter_enqueue" function
pointer or DEV_TX_OFFLOAD_MT_LOCKFREE flag is NOT set on all ethernet devices
_then_ in common code we can assign eth_tx_adapter_enqueue function
pointer as your generic Tx adapter function pointer.
3) I think, you can focus only on generic "consumer" case as you can not
test "worker_tx" case. We are planning to add more optimized raw
"worker_tx" case in driver(Point 2 will allow that by having driver
specific "eth_tx_adapter_enqueue" function pointer).
/Jerin
>
> Thanks,
> Nikhil
>
