.. SPDX-License-Identifier: BSD-3-Clause Copyright(c) 2017 Intel Corporation. Event Ethernet Tx Adapter Library ================================= The DPDK Eventdev API allows the application to use an event driven programming model for packet processing in which the event device distributes events referencing packets to the application cores in a dynamic load balanced fashion while handling atomicity and packet ordering. Event adapters provide the interface between the ethernet, crypto and timer devices and the event device. Event adapter APIs enable common application code by abstracting PMD specific capabilities. The Event ethernet Tx adapter provides configuration and data path APIs for the transmit stage of the application allowing the same application code to use eventdev PMD support or in its absence, a common implementation. In the common implementation, the application enqueues mbufs to the adapter which runs as a rte_service function. The service function dequeues events from its event port and transmits the mbufs referenced by these events. API Walk-through ---------------- This section will introduce the reader to the adapter API. The application has to first instantiate an adapter which is associated with a single eventdev, next the adapter instance is configured with Tx queues, finally the adapter is started and the application can start enqueuing mbufs to it. Creating an Adapter Instance ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ An adapter instance is created using ``rte_event_eth_tx_adapter_create()``. This function is passed the event device to be associated with the adapter and port configuration for the adapter to setup an event port if the adapter needs to use a service function. If the application desires to have finer control of eventdev port configuration, it can use the ``rte_event_eth_tx_adapter_create_ext()`` function. The ``rte_event_eth_tx_adapter_create_ext()`` function is passed a callback function. The callback function is invoked if the adapter needs to use a service function and needs to create an event port for it. The callback is expected to fill the ``struct rte_event_eth_tx_adapter_conf`` structure passed to it. .. code-block:: c struct rte_event_dev_info dev_info; struct rte_event_port_conf tx_p_conf = {0}; err = rte_event_dev_info_get(id, &dev_info); tx_p_conf.new_event_threshold = dev_info.max_num_events; tx_p_conf.dequeue_depth = dev_info.max_event_port_dequeue_depth; tx_p_conf.enqueue_depth = dev_info.max_event_port_enqueue_depth; err = rte_event_eth_tx_adapter_create(id, dev_id, &tx_p_conf); Event device configuration for service based adapter ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When ``rte_event_eth_tx_adapter_create()`` is used for creating adapter instance, ``rte_event_dev_config::nb_event_ports`` is automatically incremented, and the event device is reconfigured with additional event port during service initialization. This event device reconfigure logic also increments the ``rte_event_dev_config::nb_single_link_event_port_queues`` parameter if the adapter event port config is of type ``RTE_EVENT_PORT_CFG_SINGLE_LINK``. Application no longer needs to configure the event device with ``rte_event_dev_config::nb_event_ports`` and ``rte_event_dev_config::nb_single_link_event_port_queues`` parameters required for eth Tx adapter when the adapter is created using the above-mentioned API. Adding Tx Queues to the Adapter Instance ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Ethdev Tx queues are added to the instance using the ``rte_event_eth_tx_adapter_queue_add()`` function. A queue value of -1 is used to indicate all queues within a device. .. code-block:: c int err = rte_event_eth_tx_adapter_queue_add(id, eth_dev_id, q); Querying Adapter Capabilities ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ``rte_event_eth_tx_adapter_caps_get()`` function allows the application to query the adapter capabilities for an eventdev and ethdev combination. Currently, the only capability flag defined is ``RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT``, the application can query this flag to determine if a service function is associated with the adapter and retrieve its service identifier using the ``rte_event_eth_tx_adapter_service_id_get()`` API. .. code-block:: c int err = rte_event_eth_tx_adapter_caps_get(dev_id, eth_dev_id, &cap); if (!(cap & RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT)) err = rte_event_eth_tx_adapter_service_id_get(id, &service_id); Linking a Queue to the Adapter's Event Port ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the adapter uses a service function as described in the previous section, the application is required to link a queue to the adapter's event port. The adapter's event port can be obtained using the ``rte_event_eth_tx_adapter_event_port_get()`` function. The queue can be configured with the ``RTE_EVENT_QUEUE_CFG_SINGLE_LINK`` since it is linked to a single event port. Configuring the Service Function ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the adapter uses a service function, the application can assign a service core to the service function as shown below. .. code-block:: c if (rte_event_eth_tx_adapter_service_id_get(id, &service_id) == 0) rte_service_map_lcore_set(service_id, TX_CORE_ID); Starting the Adapter Instance ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The application calls ``rte_event_eth_tx_adapter_start()`` to start the adapter. This function calls the start callback of the eventdev PMD if supported, and the ``rte_service_run_state_set()`` to enable the service function if one exists. Enqueuing Packets to the Adapter ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The application needs to notify the adapter about the transmit port and queue used to send the packet. The transmit port is set in the ``struct rte mbuf::port`` field and the transmit queue is set using the ``rte_event_eth_tx_adapter_txq_set()`` function. If the eventdev PMD supports the ``RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT`` capability for a given ethernet device, the application should use the ``rte_event_eth_tx_adapter_enqueue()`` function to enqueue packets to the adapter. If the adapter uses a service function for the ethernet device then the application should use the ``rte_event_enqueue_burst()`` function. .. code-block:: c struct rte_event event; if (cap & RTE_EVENT_ETH_TX_ADAPTER_CAP_INTERNAL_PORT) { event.mbuf = m; eq_flags = 0; m->port = tx_port; rte_event_eth_tx_adapter_txq_set(m, tx_queue_id); rte_event_eth_tx_adapter_enqueue(dev_id, ev_port, &event, 1, eq_flags); } else { event.queue_id = qid; /* event queue linked to adapter port */ event.op = RTE_EVENT_OP_NEW; event.event_type = RTE_EVENT_TYPE_CPU; event.sched_type = RTE_SCHED_TYPE_ATOMIC; event.mbuf = m; m->port = tx_port; rte_event_eth_tx_adapter_txq_set(m, tx_queue_id); rte_event_enqueue_burst(dev_id, ev_port, &event, 1); } Getting Adapter Statistics ~~~~~~~~~~~~~~~~~~~~~~~~~~ The ``rte_event_eth_tx_adapter_stats_get()`` function reports counters defined in struct ``rte_event_eth_tx_adapter_stats``. The counter values are the sum of the counts from the eventdev PMD callback if the callback is supported, and the counts maintained by the service function, if one exists. Getting Adapter Instance ID ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The ``rte_event_eth_tx_adapter_instance_get()`` function reports Tx adapter instance ID for a specified ethernet device ID and Tx queue index. Tx event vectorization ~~~~~~~~~~~~~~~~~~~~~~ The event device, ethernet device pairs which support the capability ``RTE_EVENT_ETH_TX_ADAPTER_CAP_EVENT_VECTOR`` can process event vector of mbufs. Additionally, application can provide a hint to the Tx adapter that all the mbufs are destined to the same ethernet port and queue by setting the bit ``rte_event_vector::attr_valid`` and filling `rte_event_vector::port`` and ``rte_event_vector::queue``. If ``rte_event_vector::attr_valid`` is not set then the Tx adapter should peek into each mbuf and transmit them to the requested ethernet port and queue pair. Queue start/stop ~~~~~~~~~~~~~~~~ The adapter can be configured to start/stop enqueueing of packets to a associated NIC queue using ``rte_event_eth_tx_adapter_queue_start()`` or ``rte_event_eth_tx_adapter_queue_stop()`` respectively. By default the queue is in start state. These APIs help avoid some unexpected behavior with application stopping ethdev Tx queues and adapter being unaware of it. With these APIs, the application can call stop API to notify adapter that corresponding ethdev Tx queue is stopped and any in-flight packets are freed by adapter dataplane code. Adapter queue stop API is called before stopping the ethdev Tx queue. When ethdev Tx queue is enabled, application can notify adapter to resume processing of the packets for that queue by calling the start API. The ethdev Tx queue is started before calling adapter start API. Start function enables the adapter runtime to start enqueueing of packets to the Tx queue. Stop function stops the adapter runtime function from enqueueing any packets to the associated Tx queue. This API also frees any packets that may have been buffered for this queue. All inflight packets destined to the queue are freed by the adapter runtime until the queue is started again. Set/Get adapter runtime configuration parameters ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The runtime configuration parameters of adapter can be set/get using ``rte_event_eth_tx_adapter_runtime_params_set()`` and ``rte_event_eth_tx_adapter_runtime_params_get()`` respectively. The parameters that can be set/get are defined in ``struct rte_event_eth_tx_adapter_runtime_params``.