2018-02-01 17:18:17 +00:00
|
|
|
.. SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
Copyright(c) 2015 Intel Corporation.
|
2015-02-25 19:46:02 +00:00
|
|
|
|
|
|
|
RX/TX Callbacks Sample Application
|
|
|
|
==================================
|
|
|
|
|
|
|
|
The RX/TX Callbacks sample application is a packet forwarding application that
|
|
|
|
demonstrates the use of user defined callbacks on received and transmitted
|
|
|
|
packets. The application performs a simple latency check, using callbacks, to
|
|
|
|
determine the time packets spend within the application.
|
|
|
|
|
|
|
|
In the sample application a user defined callback is applied to all received
|
|
|
|
packets to add a timestamp. A separate callback is applied to all packets
|
|
|
|
prior to transmission to calculate the elapsed time, in CPU cycles.
|
|
|
|
|
|
|
|
|
|
|
|
Compiling the Application
|
|
|
|
-------------------------
|
|
|
|
|
2017-10-25 15:50:59 +00:00
|
|
|
To compile the sample application see :doc:`compiling`.
|
2015-02-25 19:46:02 +00:00
|
|
|
|
2017-10-25 15:50:59 +00:00
|
|
|
The application is located in the ``rxtx_callbacks`` sub-directory.
|
2015-02-25 19:46:02 +00:00
|
|
|
|
|
|
|
The callbacks feature requires that the ``CONFIG_RTE_ETHDEV_RXTX_CALLBACKS``
|
|
|
|
setting is on in the ``config/common_`` config file that applies to the
|
|
|
|
target. This is generally on by default:
|
|
|
|
|
|
|
|
.. code-block:: console
|
|
|
|
|
|
|
|
CONFIG_RTE_ETHDEV_RXTX_CALLBACKS=y
|
|
|
|
|
|
|
|
Running the Application
|
|
|
|
-----------------------
|
|
|
|
|
|
|
|
To run the example in a ``linuxapp`` environment:
|
|
|
|
|
|
|
|
.. code-block:: console
|
|
|
|
|
2017-02-27 19:13:40 +00:00
|
|
|
./build/rxtx_callbacks -l 1 -n 4
|
2015-02-25 19:46:02 +00:00
|
|
|
|
|
|
|
Refer to *DPDK Getting Started Guide* for general information on running
|
|
|
|
applications and the Environment Abstraction Layer (EAL) options.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Explanation
|
|
|
|
-----------
|
|
|
|
|
|
|
|
The ``rxtx_callbacks`` application is mainly a simple forwarding application
|
|
|
|
based on the :doc:`skeleton`. See that section of the documentation for more
|
|
|
|
details of the forwarding part of the application.
|
|
|
|
|
|
|
|
The sections below explain the additional RX/TX callback code.
|
|
|
|
|
|
|
|
|
|
|
|
The Main Function
|
|
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
|
|
|
|
The ``main()`` function performs the application initialization and calls the
|
|
|
|
execution threads for each lcore. This function is effectively identical to
|
|
|
|
the ``main()`` function explained in :doc:`skeleton`.
|
|
|
|
|
|
|
|
The ``lcore_main()`` function is also identical.
|
|
|
|
|
|
|
|
The main difference is in the user defined ``port_init()`` function where the
|
|
|
|
callbacks are added. This is explained in the next section:
|
|
|
|
|
|
|
|
|
|
|
|
The Port Initialization Function
|
|
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
|
|
|
|
The main functional part of the port initialization is shown below with
|
|
|
|
comments:
|
|
|
|
|
|
|
|
.. code-block:: c
|
|
|
|
|
|
|
|
static inline int
|
2017-10-13 13:17:01 +00:00
|
|
|
port_init(uint16_t port, struct rte_mempool *mbuf_pool)
|
2015-02-25 19:46:02 +00:00
|
|
|
{
|
|
|
|
struct rte_eth_conf port_conf = port_conf_default;
|
|
|
|
const uint16_t rx_rings = 1, tx_rings = 1;
|
|
|
|
struct ether_addr addr;
|
|
|
|
int retval;
|
|
|
|
uint16_t q;
|
|
|
|
|
|
|
|
/* Configure the Ethernet device. */
|
|
|
|
retval = rte_eth_dev_configure(port, rx_rings, tx_rings, &port_conf);
|
|
|
|
if (retval != 0)
|
|
|
|
return retval;
|
|
|
|
|
|
|
|
/* Allocate and set up 1 RX queue per Ethernet port. */
|
|
|
|
for (q = 0; q < rx_rings; q++) {
|
|
|
|
retval = rte_eth_rx_queue_setup(port, q, RX_RING_SIZE,
|
|
|
|
rte_eth_dev_socket_id(port), NULL, mbuf_pool);
|
|
|
|
if (retval < 0)
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Allocate and set up 1 TX queue per Ethernet port. */
|
|
|
|
for (q = 0; q < tx_rings; q++) {
|
|
|
|
retval = rte_eth_tx_queue_setup(port, q, TX_RING_SIZE,
|
|
|
|
rte_eth_dev_socket_id(port), NULL);
|
|
|
|
if (retval < 0)
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Start the Ethernet port. */
|
|
|
|
retval = rte_eth_dev_start(port);
|
|
|
|
if (retval < 0)
|
|
|
|
return retval;
|
|
|
|
|
|
|
|
/* Enable RX in promiscuous mode for the Ethernet device. */
|
|
|
|
rte_eth_promiscuous_enable(port);
|
|
|
|
|
|
|
|
|
|
|
|
/* Add the callbacks for RX and TX.*/
|
|
|
|
rte_eth_add_rx_callback(port, 0, add_timestamps, NULL);
|
|
|
|
rte_eth_add_tx_callback(port, 0, calc_latency, NULL);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
The RX and TX callbacks are added to the ports/queues as function pointers:
|
|
|
|
|
|
|
|
.. code-block:: c
|
|
|
|
|
|
|
|
rte_eth_add_rx_callback(port, 0, add_timestamps, NULL);
|
|
|
|
rte_eth_add_tx_callback(port, 0, calc_latency, NULL);
|
|
|
|
|
|
|
|
More than one callback can be added and additional information can be passed
|
|
|
|
to callback function pointers as a ``void*``. In the examples above ``NULL``
|
|
|
|
is used.
|
|
|
|
|
|
|
|
The ``add_timestamps()`` and ``calc_latency()`` functions are explained below.
|
|
|
|
|
|
|
|
|
|
|
|
The add_timestamps() Callback
|
|
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
|
|
|
|
The ``add_timestamps()`` callback is added to the RX port and is applied to
|
|
|
|
all packets received:
|
|
|
|
|
|
|
|
.. code-block:: c
|
|
|
|
|
|
|
|
static uint16_t
|
2017-10-13 13:17:01 +00:00
|
|
|
add_timestamps(uint16_t port __rte_unused, uint16_t qidx __rte_unused,
|
2015-02-25 19:46:02 +00:00
|
|
|
struct rte_mbuf **pkts, uint16_t nb_pkts, void *_ __rte_unused)
|
|
|
|
{
|
|
|
|
unsigned i;
|
|
|
|
uint64_t now = rte_rdtsc();
|
|
|
|
|
|
|
|
for (i = 0; i < nb_pkts; i++)
|
|
|
|
pkts[i]->udata64 = now;
|
|
|
|
|
|
|
|
return nb_pkts;
|
|
|
|
}
|
|
|
|
|
|
|
|
The DPDK function ``rte_rdtsc()`` is used to add a cycle count timestamp to
|
|
|
|
each packet (see the *cycles* section of the *DPDK API Documentation* for
|
|
|
|
details).
|
|
|
|
|
|
|
|
|
|
|
|
The calc_latency() Callback
|
|
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
|
|
|
|
The ``calc_latency()`` callback is added to the TX port and is applied to all
|
|
|
|
packets prior to transmission:
|
|
|
|
|
|
|
|
.. code-block:: c
|
|
|
|
|
|
|
|
static uint16_t
|
2017-10-13 13:17:01 +00:00
|
|
|
calc_latency(uint16_t port __rte_unused, uint16_t qidx __rte_unused,
|
2015-02-25 19:46:02 +00:00
|
|
|
struct rte_mbuf **pkts, uint16_t nb_pkts, void *_ __rte_unused)
|
|
|
|
{
|
|
|
|
uint64_t cycles = 0;
|
|
|
|
uint64_t now = rte_rdtsc();
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
for (i = 0; i < nb_pkts; i++)
|
|
|
|
cycles += now - pkts[i]->udata64;
|
|
|
|
|
|
|
|
latency_numbers.total_cycles += cycles;
|
|
|
|
latency_numbers.total_pkts += nb_pkts;
|
|
|
|
|
|
|
|
if (latency_numbers.total_pkts > (100 * 1000 * 1000ULL)) {
|
|
|
|
printf("Latency = %"PRIu64" cycles\n",
|
|
|
|
latency_numbers.total_cycles / latency_numbers.total_pkts);
|
|
|
|
|
|
|
|
latency_numbers.total_cycles = latency_numbers.total_pkts = 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
return nb_pkts;
|
|
|
|
}
|
|
|
|
|
|
|
|
The ``calc_latency()`` function accumulates the total number of packets and
|
|
|
|
the total number of cycles used. Once more than 100 million packets have been
|
|
|
|
transmitted the average cycle count per packet is printed out and the counters
|
|
|
|
are reset.
|