3429d6dd5c
In this patch,
* It is possible to switch the running mode of the distributor
using the command line argument.
* With "-c" parameter, you can run RX and Distributor
on the same core.
* Without "-c" parameter, you can run RX and Distributor
on the different core.
* Consecutive termination of the lcores fixed.
The termination order was wrong, and you couldn't terminate the
application while traffic was capturing. The current order is
RX -> Distributor -> TX -> Workers
* When "-c" parameter is active, the wasted distributor core is
also deactivated in the main function.
Signed-off-by: Abdullah Ömer Yamaç <omer.yamac@ceng.metu.edu.tr>
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6.2 KiB
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154 lines
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.. SPDX-License-Identifier: BSD-3-Clause
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Copyright(c) 2010-2014 Intel Corporation.
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Distributor Sample Application
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==============================
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The distributor sample application is a simple example of packet distribution
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to cores using the Data Plane Development Kit (DPDK). It also makes use of
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Intel Speed Select Technology - Base Frequency (Intel SST-BF) to pin the
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distributor to the higher frequency core if available.
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Overview
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--------
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The distributor application performs the distribution of packets that are received
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on an RX_PORT to different cores. When processed by the cores, the destination
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port of a packet is the port from the enabled port mask adjacent to the one on
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which the packet was received, that is, if the first four ports are enabled
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(port mask 0xf), ports 0 and 1 RX/TX into each other, and ports 2 and 3 RX/TX
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into each other.
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This application can be used to benchmark performance using the traffic
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generator as shown in the figure below.
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.. _figure_dist_perf:
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.. figure:: img/dist_perf.*
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Performance Benchmarking Setup (Basic Environment)
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Compiling the Application
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-------------------------
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To compile the sample application see :doc:`compiling`.
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The application is located in the ``distributor`` sub-directory.
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Running the Application
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-----------------------
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#. The application has a number of command line options:
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.. code-block:: console
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./<build-dir>/examples/dpdk-distributor [EAL options] -- -p PORTMASK [-c]
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where,
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* -p PORTMASK: Hexadecimal bitmask of ports to configure
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* -c: Combines the RX core with distribution core
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#. To run the application in linux environment with 10 lcores, 4 ports,
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issue the command:
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.. code-block:: console
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$ ./<build-dir>/examples/dpdk-distributor -l 1-9,22 -n 4 -- -p f
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#. Refer to the DPDK Getting Started Guide for general information on running
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applications and the Environment Abstraction Layer (EAL) options.
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Explanation
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-----------
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The distributor application consists of four types of threads: a receive
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thread (``lcore_rx()``), a distributor thread (``lcore_dist()``), a set of
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worker threads (``lcore_worker()``), and a transmit thread(``lcore_tx()``).
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How these threads work together is shown in :numref:`figure_dist_app` below.
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The ``main()`` function launches threads of these four types. Each thread
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has a while loop which will be doing processing and which is terminated
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only upon SIGINT or ctrl+C.
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The receive thread receives the packets using ``rte_eth_rx_burst()`` and will
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enqueue them to an rte_ring. The distributor thread will dequeue the packets
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from the ring and assign them to workers (using ``rte_distributor_process()`` API).
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This assignment is based on the tag (or flow ID) of the packet - indicated by
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the hash field in the mbuf. For IP traffic, this field is automatically filled
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by the NIC with the "usr" hash value for the packet, which works as a per-flow
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tag. The distributor thread communicates with the worker threads using a
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cache-line swapping mechanism, passing up to 8 mbuf pointers at a time
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(one cache line) to each worker.
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More than one worker thread can exist as part of the application, and these
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worker threads do simple packet processing by requesting packets from
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the distributor, doing a simple XOR operation on the input port mbuf field
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(to indicate the output port which will be used later for packet transmission)
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and then finally returning the packets back to the distributor thread.
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The distributor thread will then call the distributor api
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``rte_distributor_returned_pkts()`` to get the processed packets, and will enqueue
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them to another rte_ring for transfer to the TX thread for transmission on the
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output port. The transmit thread will dequeue the packets from the ring and
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transmit them on the output port specified in packet mbuf.
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Users who wish to terminate the running of the application have to press ctrl+C
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(or send SIGINT to the app). Upon this signal, a signal handler provided
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in the application will terminate all running threads gracefully and print
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final statistics to the user.
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.. _figure_dist_app:
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.. figure:: img/dist_app.*
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Distributor Sample Application Layout
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Intel SST-BF Support
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--------------------
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In DPDK 19.05, support was added to the power management library for
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Intel-SST-BF, a technology that allows some cores to run at a higher
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frequency than others. An application note for Intel SST-BF is available,
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and is entitled
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`Intel Speed Select Technology – Base Frequency - Enhancing Performance <https://builders.intel.com/docs/networkbuilders/intel-speed-select-technology-base-frequency-enhancing-performance.pdf>`_
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The distributor application was also enhanced to be aware of these higher
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frequency SST-BF cores, and when starting the application, if high frequency
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SST-BF cores are present in the core mask, the application will identify these
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cores and pin the workloads appropriately. The distributor core is usually
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the bottleneck, so this is given first choice of the high frequency SST-BF
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cores, followed by the rx core and the tx core.
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Debug Logging Support
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---------------------
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Debug logging is provided as part of the application; the user needs to uncomment
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the line "#define DEBUG" defined in start of the application in main.c to enable debug logs.
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Statistics
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----------
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The main function will print statistics on the console every second. These
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statistics include the number of packets enqueued and dequeued at each stage
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in the application, and also key statistics per worker, including how many
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packets of each burst size (1-8) were sent to each worker thread.
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Application Initialization
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--------------------------
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Command line parsing is done in the same way as it is done in the L2 Forwarding Sample
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Application. See :ref:`l2_fwd_app_cmd_arguments`.
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Mbuf pool initialization is done in the same way as it is done in the L2 Forwarding
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Sample Application. See :ref:`l2_fwd_app_mbuf_init`.
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Driver Initialization is done in same way as it is done in the L2 Forwarding Sample
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Application. See :ref:`l2_fwd_app_dvr_init`.
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RX queue initialization is done in the same way as it is done in the L2 Forwarding
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Sample Application. See :ref:`l2_fwd_app_rx_init`.
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TX queue initialization is done in the same way as it is done in the L2 Forwarding
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Sample Application. See :ref:`l2_fwd_app_tx_init`.
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