1.. BSD LICENSE 2 Copyright(c) 2016 Intel Corporation. All rights reserved. 3 All rights reserved. 4 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions 7 are met: 8 9 * Redistributions of source code must retain the above copyright 10 notice, this list of conditions and the following disclaimer. 11 * Redistributions in binary form must reproduce the above copyright 12 notice, this list of conditions and the following disclaimer in 13 the documentation and/or other materials provided with the 14 distribution. 15 * Neither the name of Intel Corporation nor the names of its 16 contributors may be used to endorse or promote products derived 17 from this software without specific prior written permission. 18 19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 32L2 Forwarding Sample Application with Cache Allocation Technology (CAT) 33======================================================================= 34 35Basic Forwarding sample application is a simple *skeleton* example of 36a forwarding application. It has been extended to make use of CAT via extended 37command line options and linking against the libpqos library. 38 39It is intended as a demonstration of the basic components of a DPDK forwarding 40application and use of the libpqos library to program CAT. 41For more detailed implementations see the L2 and L3 forwarding 42sample applications. 43 44CAT and Code Data Prioritization (CDP) features allow management of the CPU's 45last level cache. CAT introduces classes of service (COS) that are essentially 46bitmasks. In current CAT implementations, a bit in a COS bitmask corresponds to 47one cache way in last level cache. 48A CPU core is always assigned to one of the CAT classes. 49By programming CPU core assignment and COS bitmasks, applications can be given 50exclusive, shared, or mixed access to the CPU's last level cache. 51CDP extends CAT so that there are two bitmasks per COS, 52one for data and one for code. 53The number of classes and number of valid bits in a COS bitmask is CPU model 54specific and COS bitmasks need to be contiguous. Sample code calls this bitmask 55``cbm`` or capacity bitmask. 56By default, after reset, all CPU cores are assigned to COS 0 and all classes 57are programmed to allow fill into all cache ways. 58CDP is off by default. 59 60For more information about CAT please see: 61 62* https://github.com/01org/intel-cmt-cat 63 64White paper demonstrating example use case: 65 66* `Increasing Platform Determinism with Platform Quality of Service for the Data Plane Development Kit <http://www.intel.com/content/www/us/en/communications/increasing-platform-determinism-pqos-dpdk-white-paper.html>`_ 67 68Compiling the Application 69------------------------- 70.. note:: 71 72 Requires ``libpqos`` from Intel's 73 `intel-cmt-cat software package <https://github.com/01org/intel-cmt-cat>`_ 74 hosted on GitHub repository. For installation notes, please see ``README`` file. 75 76 GIT: 77 78 * https://github.com/01org/intel-cmt-cat 79 80 81#. To compile the application export the path to PQoS lib 82 and the DPDK source tree and go to the example directory: 83 84 .. code-block:: console 85 86 export PQOS_INSTALL_PATH=/path/to/libpqos 87 88 89To compile the sample application see :doc:`compiling`. 90 91The application is located in the ``l2fwd-cat`` sub-directory. 92 93 94Running the Application 95----------------------- 96 97To run the example in a ``linuxapp`` environment and enable CAT on cpus 0-2: 98 99.. code-block:: console 100 101 ./build/l2fwd-cat -l 1 -n 4 -- --l3ca="0x3@(0-2)" 102 103or to enable CAT and CDP on cpus 1,3: 104 105.. code-block:: console 106 107 ./build/l2fwd-cat -l 1 -n 4 -- --l3ca="(0x00C00,0x00300)@(1,3)" 108 109If CDP is not supported it will fail with following error message: 110 111.. code-block:: console 112 113 PQOS: CDP requested but not supported. 114 PQOS: Requested CAT configuration is not valid! 115 PQOS: Shutting down PQoS library... 116 EAL: Error - exiting with code: 1 117 Cause: PQOS: L3CA init failed! 118 119The option to enable CAT is: 120 121* ``--l3ca='<common_cbm@cpus>[,<(code_cbm,data_cbm)@cpus>...]'``: 122 123 where ``cbm`` stands for capacity bitmask and must be expressed in 124 hexadecimal form. 125 126 ``common_cbm`` is a single mask, for a CDP enabled system, a group of two 127 masks (``code_cbm`` and ``data_cbm``) is used. 128 129 ``(`` and ``)`` are necessary if it's a group. 130 131 ``cpus`` could be a single digit/range or a group and must be expressed in 132 decimal form. 133 134 ``(`` and ``)`` are necessary if it's a group. 135 136 e.g. ``--l3ca='0x00F00@(1,3),0x0FF00@(4-6),0xF0000@7'`` 137 138 * cpus 1 and 3 share its 4 ways with cpus 4, 5 and 6; 139 140 * cpus 4, 5 and 6 share half (4 out of 8 ways) of its L3 with cpus 1 and 3; 141 142 * cpus 4, 5 and 6 have exclusive access to 4 out of 8 ways; 143 144 * cpu 7 has exclusive access to all of its 4 ways; 145 146 e.g. ``--l3ca='(0x00C00,0x00300)@(1,3)'`` for CDP enabled system 147 148 * cpus 1 and 3 have access to 2 ways for code and 2 ways for data, code and 149 data ways are not overlapping. 150 151 152Refer to *DPDK Getting Started Guide* for general information on running 153applications and the Environment Abstraction Layer (EAL) options. 154 155 156To reset or list CAT configuration and control CDP please use ``pqos`` tool 157from Intel's 158`intel-cmt-cat software package <https://github.com/01org/intel-cmt-cat>`_. 159 160To enabled or disable CDP: 161 162.. code-block:: console 163 164 sudo ./pqos -S cdp-on 165 166 sudo ./pqos -S cdp-off 167 168to reset CAT configuration: 169 170.. code-block:: console 171 172 sudo ./pqos -R 173 174to list CAT config: 175 176.. code-block:: console 177 178 sudo ./pqos -s 179 180For more info about ``pqos`` tool please see its man page or 181`intel-cmt-cat wiki <https://github.com/01org/intel-cmt-cat/wiki>`_. 182 183 184Explanation 185----------- 186 187The following sections provide an explanation of the main components of the 188code. 189 190All DPDK library functions used in the sample code are prefixed with ``rte_`` 191and are explained in detail in the *DPDK API Documentation*. 192 193 194The Main Function 195~~~~~~~~~~~~~~~~~ 196 197The ``main()`` function performs the initialization and calls the execution 198threads for each lcore. 199 200The first task is to initialize the Environment Abstraction Layer (EAL). The 201``argc`` and ``argv`` arguments are provided to the ``rte_eal_init()`` 202function. The value returned is the number of parsed arguments: 203 204.. code-block:: c 205 206 int ret = rte_eal_init(argc, argv); 207 if (ret < 0) 208 rte_exit(EXIT_FAILURE, "Error with EAL initialization\n"); 209 210The next task is to initialize the PQoS library and configure CAT. The 211``argc`` and ``argv`` arguments are provided to the ``cat_init()`` 212function. The value returned is the number of parsed arguments: 213 214.. code-block:: c 215 216 int ret = cat_init(argc, argv); 217 if (ret < 0) 218 rte_exit(EXIT_FAILURE, "PQOS: L3CA init failed!\n"); 219 220``cat_init()`` is a wrapper function which parses the command, validates 221the requested parameters and configures CAT accordingly. 222 223Parsing of command line arguments is done in ``parse_args(...)``. 224libpqos is then initialized with the ``pqos_init(...)`` call. Next, libpqos is 225queried for system CPU information and L3CA capabilities via 226``pqos_cap_get(...)`` and ``pqos_cap_get_type(..., PQOS_CAP_TYPE_L3CA, ...)`` 227calls. When all capability and topology information is collected, the requested 228CAT configuration is validated. A check is then performed (on per socket basis) 229for a sufficient number of un-associated COS. COS are selected and 230configured via the ``pqos_l3ca_set(...)`` call. Finally, COS are associated to 231relevant CPUs via ``pqos_l3ca_assoc_set(...)`` calls. 232 233``atexit(...)`` is used to register ``cat_exit(...)`` to be called on 234a clean exit. ``cat_exit(...)`` performs a simple CAT clean-up, by associating 235COS 0 to all involved CPUs via ``pqos_l3ca_assoc_set(...)`` calls. 236