From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id CA0415A17 for ; Wed, 25 Feb 2015 20:46:49 +0100 (CET) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP; 25 Feb 2015 11:38:39 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,646,1418112000"; d="scan'208";a="690743733" Received: from irvmail001.ir.intel.com ([163.33.26.43]) by orsmga002.jf.intel.com with ESMTP; 25 Feb 2015 11:46:40 -0800 Received: from sivswdev02.ir.intel.com (sivswdev02.ir.intel.com [10.237.217.46]) by irvmail001.ir.intel.com (8.14.3/8.13.6/MailSET/Hub) with ESMTP id t1PJkc4t005017; Wed, 25 Feb 2015 19:46:38 GMT Received: from sivswdev02.ir.intel.com (localhost [127.0.0.1]) by sivswdev02.ir.intel.com with ESMTP id t1PJkc3r009095; Wed, 25 Feb 2015 19:46:38 GMT Received: (from jmcnam2x@localhost) by sivswdev02.ir.intel.com with id t1PJkcmf009091; Wed, 25 Feb 2015 19:46:38 GMT From: John McNamara To: dev@dpdk.org Date: Wed, 25 Feb 2015 19:46:01 +0000 Message-Id: <1424893562-8740-3-git-send-email-john.mcnamara@intel.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1424893562-8740-1-git-send-email-john.mcnamara@intel.com> References: <1424893562-8740-1-git-send-email-john.mcnamara@intel.com> Subject: [dpdk-dev] [PATCH 2/3] doc: add docs for basic forwarding skeleton app X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Feb 2015 19:46:50 -0000 Added a sample application guide for the basic forwarding /skeleton app. Signed-off-by: John McNamara --- MAINTAINERS | 3 + doc/guides/sample_app_ug/index.rst | 3 +- doc/guides/sample_app_ug/skeleton.rst | 338 +++++++++++++++++++++++++++++++++ 3 files changed, 343 insertions(+), 1 deletions(-) create mode 100644 doc/guides/sample_app_ug/skeleton.rst diff --git a/MAINTAINERS b/MAINTAINERS index 349ad2b..86c1c6b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -444,7 +444,10 @@ M: Bruce Richardson M: John McNamara F: examples/rxtx_callbacks/ +M: Bruce Richardson +M: John McNamara F: examples/skeleton/ +F: doc/guides/sample_app_ug/skeleton.rst F: examples/vmdq/ F: examples/vmdq_dcb/ diff --git a/doc/guides/sample_app_ug/index.rst b/doc/guides/sample_app_ug/index.rst index 5720181..4e9d59b 100644 --- a/doc/guides/sample_app_ug/index.rst +++ b/doc/guides/sample_app_ug/index.rst @@ -1,5 +1,5 @@ .. BSD LICENSE - Copyright(c) 2010-2014 Intel Corporation. All rights reserved. + Copyright(c) 2010-2015 Intel Corporation. All rights reserved. All rights reserved. Redistribution and use in source and binary forms, with or without @@ -43,6 +43,7 @@ Sample Applications User Guide cmd_line exception_path hello_world + skeleton ip_frag ipv4_multicast ip_reassembly diff --git a/doc/guides/sample_app_ug/skeleton.rst b/doc/guides/sample_app_ug/skeleton.rst new file mode 100644 index 0000000..e832c13 --- /dev/null +++ b/doc/guides/sample_app_ug/skeleton.rst @@ -0,0 +1,338 @@ +.. BSD LICENSE + Copyright(c) 2015 Intel Corporation. All rights reserved. + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in + the documentation and/or other materials provided with the + distribution. + * Neither the name of Intel Corporation nor the names of its + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + + +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 application export the path to the DPDK source tree and go to +the example directory: + +.. code-block:: console + + export RTE_SDK=/path/to/rte_sdk + + cd ${RTE_SDK}/examples/skeleton + +Set the target, for example: + +.. code-block:: console + + export RTE_TARGET=x86_64-native-linuxapp-gcc + +See the *DPDK Getting Started* Guide for possible ``RTE_TARGET`` values. + +Build the application as follows: + +.. code-block:: console + + make + + +Running the Application +----------------------- + +To run the example in a ``linuxapp`` environment: + +.. code-block:: console + + ./build/basicfwd -c 2 -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(uint8_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 uint8_t nb_ports = rte_eth_dev_count(); + uint8_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``. -- 1.7.4.1