5630257fcc
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
290 lines
8.6 KiB
ReStructuredText
290 lines
8.6 KiB
ReStructuredText
.. SPDX-License-Identifier: BSD-3-Clause
|
|
Copyright(c) 2015 Intel Corporation.
|
|
|
|
Basic Forwarding Sample Application
|
|
===================================
|
|
|
|
The Basic Forwarding sample application is a simple *skeleton* example of a
|
|
forwarding application.
|
|
|
|
It is intended as a demonstration of the basic components of a DPDK forwarding
|
|
application. For more detailed implementations see the L2 and L3 forwarding
|
|
sample applications.
|
|
|
|
Compiling the Application
|
|
-------------------------
|
|
|
|
To compile the sample application see :doc:`compiling`.
|
|
|
|
The application is located in the ``skeleton`` sub-directory.
|
|
|
|
Running the Application
|
|
-----------------------
|
|
|
|
To run the example in a ``linuxapp`` environment:
|
|
|
|
.. code-block:: console
|
|
|
|
./build/basicfwd -l 1 -n 4
|
|
|
|
Refer to *DPDK Getting Started Guide* for general information on running
|
|
applications and the Environment Abstraction Layer (EAL) options.
|
|
|
|
|
|
Explanation
|
|
-----------
|
|
|
|
The following sections provide an explanation of the main components of the
|
|
code.
|
|
|
|
All DPDK library functions used in the sample code are prefixed with ``rte_``
|
|
and are explained in detail in the *DPDK API Documentation*.
|
|
|
|
|
|
The Main Function
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
The ``main()`` function performs the initialization and calls the execution
|
|
threads for each lcore.
|
|
|
|
The first task is to initialize the Environment Abstraction Layer (EAL). The
|
|
``argc`` and ``argv`` arguments are provided to the ``rte_eal_init()``
|
|
function. The value returned is the number of parsed arguments:
|
|
|
|
.. code-block:: c
|
|
|
|
int ret = rte_eal_init(argc, argv);
|
|
if (ret < 0)
|
|
rte_exit(EXIT_FAILURE, "Error with EAL initialization\n");
|
|
|
|
|
|
The ``main()`` also allocates a mempool to hold the mbufs (Message Buffers)
|
|
used by the application:
|
|
|
|
.. code-block:: c
|
|
|
|
mbuf_pool = rte_mempool_create("MBUF_POOL",
|
|
NUM_MBUFS * nb_ports,
|
|
MBUF_SIZE,
|
|
MBUF_CACHE_SIZE,
|
|
sizeof(struct rte_pktmbuf_pool_private),
|
|
rte_pktmbuf_pool_init, NULL,
|
|
rte_pktmbuf_init, NULL,
|
|
rte_socket_id(),
|
|
0);
|
|
|
|
Mbufs are the packet buffer structure used by DPDK. They are explained in
|
|
detail in the "Mbuf Library" section of the *DPDK Programmer's Guide*.
|
|
|
|
The ``main()`` function also initializes all the ports using the user defined
|
|
``port_init()`` function which is explained in the next section:
|
|
|
|
.. code-block:: c
|
|
|
|
for (portid = 0; portid < nb_ports; portid++) {
|
|
if (port_init(portid, mbuf_pool) != 0) {
|
|
rte_exit(EXIT_FAILURE,
|
|
"Cannot init port %" PRIu8 "\n", portid);
|
|
}
|
|
}
|
|
|
|
|
|
Once the initialization is complete, the application is ready to launch a
|
|
function on an lcore. In this example ``lcore_main()`` is called on a single
|
|
lcore.
|
|
|
|
|
|
.. code-block:: c
|
|
|
|
lcore_main();
|
|
|
|
The ``lcore_main()`` function is explained below.
|
|
|
|
|
|
|
|
The Port Initialization Function
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The main functional part of the port initialization used in the Basic
|
|
Forwarding application is shown below:
|
|
|
|
.. code-block:: c
|
|
|
|
static inline int
|
|
port_init(uint16_t port, struct rte_mempool *mbuf_pool)
|
|
{
|
|
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;
|
|
|
|
if (port >= rte_eth_dev_count())
|
|
return -1;
|
|
|
|
/* 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);
|
|
|
|
return 0;
|
|
}
|
|
|
|
The Ethernet ports are configured with default settings using the
|
|
``rte_eth_dev_configure()`` function and the ``port_conf_default`` struct:
|
|
|
|
.. code-block:: c
|
|
|
|
static const struct rte_eth_conf port_conf_default = {
|
|
.rxmode = { .max_rx_pkt_len = ETHER_MAX_LEN }
|
|
};
|
|
|
|
For this example the ports are set up with 1 RX and 1 TX queue using the
|
|
``rte_eth_rx_queue_setup()`` and ``rte_eth_tx_queue_setup()`` functions.
|
|
|
|
The Ethernet port is then started:
|
|
|
|
.. code-block:: c
|
|
|
|
retval = rte_eth_dev_start(port);
|
|
|
|
|
|
Finally the RX port is set in promiscuous mode:
|
|
|
|
.. code-block:: c
|
|
|
|
rte_eth_promiscuous_enable(port);
|
|
|
|
|
|
The Lcores Main
|
|
~~~~~~~~~~~~~~~
|
|
|
|
As we saw above the ``main()`` function calls an application function on the
|
|
available lcores. For the Basic Forwarding application the lcore function
|
|
looks like the following:
|
|
|
|
.. code-block:: c
|
|
|
|
static __attribute__((noreturn)) void
|
|
lcore_main(void)
|
|
{
|
|
const uint16_t nb_ports = rte_eth_dev_count();
|
|
uint16_t port;
|
|
|
|
/*
|
|
* Check that the port is on the same NUMA node as the polling thread
|
|
* for best performance.
|
|
*/
|
|
for (port = 0; port < nb_ports; port++)
|
|
if (rte_eth_dev_socket_id(port) > 0 &&
|
|
rte_eth_dev_socket_id(port) !=
|
|
(int)rte_socket_id())
|
|
printf("WARNING, port %u is on remote NUMA node to "
|
|
"polling thread.\n\tPerformance will "
|
|
"not be optimal.\n", port);
|
|
|
|
printf("\nCore %u forwarding packets. [Ctrl+C to quit]\n",
|
|
rte_lcore_id());
|
|
|
|
/* Run until the application is quit or killed. */
|
|
for (;;) {
|
|
/*
|
|
* Receive packets on a port and forward them on the paired
|
|
* port. The mapping is 0 -> 1, 1 -> 0, 2 -> 3, 3 -> 2, etc.
|
|
*/
|
|
for (port = 0; port < nb_ports; port++) {
|
|
|
|
/* Get burst of RX packets, from first port of pair. */
|
|
struct rte_mbuf *bufs[BURST_SIZE];
|
|
const uint16_t nb_rx = rte_eth_rx_burst(port, 0,
|
|
bufs, BURST_SIZE);
|
|
|
|
if (unlikely(nb_rx == 0))
|
|
continue;
|
|
|
|
/* Send burst of TX packets, to second port of pair. */
|
|
const uint16_t nb_tx = rte_eth_tx_burst(port ^ 1, 0,
|
|
bufs, nb_rx);
|
|
|
|
/* Free any unsent packets. */
|
|
if (unlikely(nb_tx < nb_rx)) {
|
|
uint16_t buf;
|
|
for (buf = nb_tx; buf < nb_rx; buf++)
|
|
rte_pktmbuf_free(bufs[buf]);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
The main work of the application is done within the loop:
|
|
|
|
.. code-block:: c
|
|
|
|
for (;;) {
|
|
for (port = 0; port < nb_ports; port++) {
|
|
|
|
/* Get burst of RX packets, from first port of pair. */
|
|
struct rte_mbuf *bufs[BURST_SIZE];
|
|
const uint16_t nb_rx = rte_eth_rx_burst(port, 0,
|
|
bufs, BURST_SIZE);
|
|
|
|
if (unlikely(nb_rx == 0))
|
|
continue;
|
|
|
|
/* Send burst of TX packets, to second port of pair. */
|
|
const uint16_t nb_tx = rte_eth_tx_burst(port ^ 1, 0,
|
|
bufs, nb_rx);
|
|
|
|
/* Free any unsent packets. */
|
|
if (unlikely(nb_tx < nb_rx)) {
|
|
uint16_t buf;
|
|
for (buf = nb_tx; buf < nb_rx; buf++)
|
|
rte_pktmbuf_free(bufs[buf]);
|
|
}
|
|
}
|
|
}
|
|
|
|
Packets are received in bursts on the RX ports and transmitted in bursts on
|
|
the TX ports. The ports are grouped in pairs with a simple mapping scheme
|
|
using the an XOR on the port number::
|
|
|
|
0 -> 1
|
|
1 -> 0
|
|
|
|
2 -> 3
|
|
3 -> 2
|
|
|
|
etc.
|
|
|
|
The ``rte_eth_tx_burst()`` function frees the memory buffers of packets that
|
|
are transmitted. If packets fail to transmit, ``(nb_tx < nb_rx)``, then they
|
|
must be freed explicitly using ``rte_pktmbuf_free()``.
|
|
|
|
The forwarding loop can be interrupted and the application closed using
|
|
``Ctrl-C``.
|