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 CB2CA5A17 for ; Wed, 25 Feb 2015 20:46:50 +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="690743735" 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 t1PJkc0b005023; 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 t1PJkctd009102; Wed, 25 Feb 2015 19:46:38 GMT Received: (from jmcnam2x@localhost) by sivswdev02.ir.intel.com with id t1PJkchn009098; Wed, 25 Feb 2015 19:46:38 GMT From: John McNamara To: dev@dpdk.org Date: Wed, 25 Feb 2015 19:46:02 +0000 Message-Id: <1424893562-8740-4-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 3/3] doc: add docs for the rxtx_callbacks sample 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 19:46:51 -0000 Added a sample application guide for the rxtx_callbacks app. Signed-off-by: John McNamara --- MAINTAINERS | 1 + doc/guides/sample_app_ug/index.rst | 1 + doc/guides/sample_app_ug/rxtx_callbacks.rst | 251 +++++++++++++++++++++++++++ 3 files changed, 253 insertions(+), 0 deletions(-) create mode 100644 doc/guides/sample_app_ug/rxtx_callbacks.rst diff --git a/MAINTAINERS b/MAINTAINERS index 86c1c6b..2ddb312 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -443,6 +443,7 @@ F: doc/guides/sample_app_ug/quota_watermark.rst M: Bruce Richardson M: John McNamara F: examples/rxtx_callbacks/ +F: doc/guides/sample_app_ug/rxtx_callbacks.rst M: Bruce Richardson M: John McNamara diff --git a/doc/guides/sample_app_ug/index.rst b/doc/guides/sample_app_ug/index.rst index 4e9d59b..4a86459 100644 --- a/doc/guides/sample_app_ug/index.rst +++ b/doc/guides/sample_app_ug/index.rst @@ -44,6 +44,7 @@ Sample Applications User Guide exception_path hello_world skeleton + rxtx_callbacks ip_frag ipv4_multicast ip_reassembly diff --git a/doc/guides/sample_app_ug/rxtx_callbacks.rst b/doc/guides/sample_app_ug/rxtx_callbacks.rst new file mode 100644 index 0000000..9df57ed --- /dev/null +++ b/doc/guides/sample_app_ug/rxtx_callbacks.rst @@ -0,0 +1,251 @@ +.. 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. + + +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 +------------------------- + +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/rxtx_callbacks + + +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. + +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 + +Build the application as follows: + +.. code-block:: console + + make + + +Running the Application +----------------------- + +To run the example in a ``linuxapp`` environment: + +.. code-block:: console + + ./build/rxtx_callbacks -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 ``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 + 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); + + + /* 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 + add_timestamps(uint8_t port __rte_unused, uint16_t qidx __rte_unused, + 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 + calc_latency(uint8_t port __rte_unused, uint16_t qidx __rte_unused, + 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. -- 1.7.4.1