ceph/src/spdk/dpdk/doc/guides/linux_gsg/build_sample_apps.rst

   1 ..  SPDX-License-Identifier: BSD-3-Clause
   2     Copyright(c) 2010-2014 Intel Corporation.
   3
   4 Compiling and Running Sample Applications
   5 =========================================
   6
   7 The chapter describes how to compile and run applications in an DPDK environment.
   8 It also provides a pointer to where sample applications are stored.
   9
  10 .. note::
  11
  12     Parts of this process can also be done using the setup script described the
  13     :ref:`linux_setup_script` section of this document.
  14
  15 Compiling a Sample Application
  16 ------------------------------
  17
  18 Once an DPDK target environment directory has been created (such as ``x86_64-native-linux-gcc``),
  19 it contains all libraries and header files required to build an application.
  20
  21 When compiling an application in the Linux* environment on the DPDK, the following variables must be exported:
  22
  23 * ``RTE_SDK`` - Points to the DPDK installation directory.
  24
  25 * ``RTE_TARGET`` - Points to the DPDK target environment directory.
  26
  27 The following is an example of creating the ``helloworld`` application, which runs in the DPDK Linux environment.
  28 This example may be found in the ``${RTE_SDK}/examples`` directory.
  29
  30 The directory contains the ``main.c`` file. This file, when combined with the libraries in the DPDK target environment,
  31 calls the various functions to initialize the DPDK environment,
  32 then launches an entry point (dispatch application) for each core to be utilized.
  33 By default, the binary is generated in the build directory.
  34
  35 .. code-block:: console
  36
  37     cd examples/helloworld/
  38     export RTE_SDK=$HOME/DPDK
  39     export RTE_TARGET=x86_64-native-linux-gcc
  40
  41     make
  42         CC main.o
  43         LD helloworld
  44         INSTALL-APP helloworld
  45         INSTALL-MAP helloworld.map
  46
  47     ls build/app
  48         helloworld helloworld.map
  49
  50 .. note::
  51
  52     In the above example, ``helloworld`` was in the directory structure of the DPDK.
  53     However, it could have been located outside the directory structure to keep the DPDK structure intact.
  54     In the following case, the ``helloworld`` application is copied to a new directory as a new starting point.
  55
  56     .. code-block:: console
  57
  58        export RTE_SDK=/home/user/DPDK
  59        cp -r $(RTE_SDK)/examples/helloworld my_rte_app
  60        cd my_rte_app/
  61        export RTE_TARGET=x86_64-native-linux-gcc
  62
  63        make
  64          CC main.o
  65          LD helloworld
  66          INSTALL-APP helloworld
  67          INSTALL-MAP helloworld.map
  68
  69 Running a Sample Application
  70 ----------------------------
  71
  72 .. warning::
  73
  74     Before running the application make sure:
  75
  76     - Hugepages setup is done.
  77     - Any kernel driver being used is loaded.
  78     - In case needed, ports being used by the application should be
  79       bound to the corresponding kernel driver.
  80
  81     refer to :ref:`linux_gsg_linux_drivers` for more details.
  82
  83 The application is linked with the DPDK target environment's Environmental Abstraction Layer (EAL) library,
  84 which provides some options that are generic to every DPDK application.
  85
  86 The following is the list of options that can be given to the EAL:
  87
  88 .. code-block:: console
  89
  90     ./rte-app [-c COREMASK | -l CORELIST] [-n NUM] [-b <domain:bus:devid.func>] \
  91               [--socket-mem=MB,...] [-d LIB.so|DIR] [-m MB] [-r NUM] [-v] [--file-prefix] \
  92               [--proc-type <primary|secondary|auto>]
  93
  94 The EAL options are as follows:
  95
  96 * ``-c COREMASK`` or ``-l CORELIST``:
  97   An hexadecimal bit mask of the cores to run on. Note that core numbering can
  98   change between platforms and should be determined beforehand. The corelist is
  99   a set of core numbers instead of a bitmap core mask.
 100
 101 * ``-n NUM``:
 102   Number of memory channels per processor socket.
 103
 104 * ``-b <domain:bus:devid.func>``:
 105   Blacklisting of ports; prevent EAL from using specified PCI device
 106   (multiple ``-b`` options are allowed).
 107
 108 * ``--use-device``:
 109   use the specified Ethernet device(s) only. Use comma-separate
 110   ``[domain:]bus:devid.func`` values. Cannot be used with ``-b`` option.
 111
 112 * ``--socket-mem``:
 113   Memory to allocate from hugepages on specific sockets. In dynamic memory mode,
 114   this memory will also be pinned (i.e. not released back to the system until
 115   application closes).
 116
 117 * ``--socket-limit``:
 118   Limit maximum memory available for allocation on each socket. Does not support
 119   legacy memory mode.
 120
 121 * ``-d``:
 122   Add a driver or driver directory to be loaded.
 123   The application should use this option to load the pmd drivers
 124   that are built as shared libraries.
 125
 126 * ``-m MB``:
 127   Memory to allocate from hugepages, regardless of processor socket. It is
 128   recommended that ``--socket-mem`` be used instead of this option.
 129
 130 * ``-r NUM``:
 131   Number of memory ranks.
 132
 133 * ``-v``:
 134   Display version information on startup.
 135
 136 * ``--huge-dir``:
 137   The directory where hugetlbfs is mounted.
 138
 139 * ``mbuf-pool-ops-name``:
 140   Pool ops name for mbuf to use.
 141
 142 * ``--file-prefix``:
 143   The prefix text used for hugepage filenames.
 144
 145 * ``--proc-type``:
 146   The type of process instance.
 147
 148 * ``--vmware-tsc-map``:
 149   Use VMware TSC map instead of native RDTSC.
 150
 151 * ``--base-virtaddr``:
 152   Specify base virtual address.
 153
 154 * ``--vfio-intr``:
 155   Specify interrupt type to be used by VFIO (has no effect if VFIO is not used).
 156
 157 * ``--legacy-mem``:
 158   Run DPDK in legacy memory mode (disable memory reserve/unreserve at runtime,
 159   but provide more IOVA-contiguous memory).
 160
 161 * ``--single-file-segments``:
 162   Store memory segments in fewer files (dynamic memory mode only - does not
 163   affect legacy memory mode).
 164
 165 The ``-c`` or ``-l`` and option is mandatory; the others are optional.
 166
 167 Copy the DPDK application binary to your target, then run the application as follows
 168 (assuming the platform has four memory channels per processor socket,
 169 and that cores 0-3 are present and are to be used for running the application)::
 170
 171     ./helloworld -l 0-3 -n 4
 172
 173 .. note::
 174
 175     The ``--proc-type`` and ``--file-prefix`` EAL options are used for running
 176     multiple DPDK processes. See the "Multi-process Sample Application"
 177     chapter in the *DPDK Sample Applications User Guide* and the *DPDK
 178     Programmers Guide* for more details.
 179
 180 Logical Core Use by Applications
 181 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 182
 183 The coremask (-c 0x0f) or corelist (-l 0-3) parameter is always mandatory for DPDK applications.
 184 Each bit of the mask corresponds to the equivalent logical core number as reported by Linux. The preferred corelist option is a cleaner method to define cores to be used.
 185 Since these logical core numbers, and their mapping to specific cores on specific NUMA sockets, can vary from platform to platform,
 186 it is recommended that the core layout for each platform be considered when choosing the coremask/corelist to use in each case.
 187
 188 On initialization of the EAL layer by an DPDK application, the logical cores to be used and their socket location are displayed.
 189 This information can also be determined for all cores on the system by examining the ``/proc/cpuinfo`` file, for example, by running cat ``/proc/cpuinfo``.
 190 The physical id attribute listed for each processor indicates the CPU socket to which it belongs.
 191 This can be useful when using other processors to understand the mapping of the logical cores to the sockets.
 192
 193 .. note::
 194
 195     A more graphical view of the logical core layout may be obtained using the ``lstopo`` Linux utility.
 196     On Fedora Linux, this may be installed and run using the following command::
 197
 198         sudo yum install hwloc
 199         ./lstopo
 200
 201 .. warning::
 202
 203     The logical core layout can change between different board layouts and should be checked before selecting an application coremask/corelist.
 204
 205 Hugepage Memory Use by Applications
 206 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 207
 208 When running an application, it is recommended to use the same amount of memory as that allocated for hugepages.
 209 This is done automatically by the DPDK application at startup,
 210 if no ``-m`` or ``--socket-mem`` parameter is passed to it when run.
 211
 212 If more memory is requested by explicitly passing a ``-m`` or ``--socket-mem`` value, the application fails.
 213 However, the application itself can also fail if the user requests less memory than the reserved amount of hugepage-memory, particularly if using the ``-m`` option.
 214 The reason is as follows.
 215 Suppose the system has 1024 reserved 2 MB pages in socket 0 and 1024 in socket 1.
 216 If the user requests 128 MB of memory, the 64 pages may not match the constraints:
 217
 218 *   The hugepage memory by be given to the application by the kernel in socket 1 only.
 219     In this case, if the application attempts to create an object, such as a ring or memory pool in socket 0, it fails.
 220     To avoid this issue, it is recommended that the ``--socket-mem`` option be used instead of the ``-m`` option.
 221
 222 *   These pages can be located anywhere in physical memory, and, although the DPDK EAL will attempt to allocate memory in contiguous blocks,
 223     it is possible that the pages will not be contiguous. In this case, the application is not able to allocate big memory pools.
 224
 225 The socket-mem option can be used to request specific amounts of memory for specific sockets.
 226 This is accomplished by supplying the ``--socket-mem`` flag followed by amounts of memory requested on each socket,
 227 for example, supply ``--socket-mem=0,512`` to try and reserve 512 MB for socket 1 only.
 228 Similarly, on a four socket system, to allocate 1 GB memory on each of sockets 0 and 2 only, the parameter ``--socket-mem=1024,0,1024`` can be used.
 229 No memory will be reserved on any CPU socket that is not explicitly referenced, for example, socket 3 in this case.
 230 If the DPDK cannot allocate enough memory on each socket, the EAL initialization fails.
 231
 232 Additional Sample Applications
 233 ------------------------------
 234
 235 Additional sample applications are included in the ${RTE_SDK}/examples directory.
 236 These sample applications may be built and run in a manner similar to that described in earlier sections in this manual.
 237 In addition, see the *DPDK Sample Applications User Guide* for a description of the application,
 238 specific instructions on compilation and execution and some explanation of the code.
 239
 240 Additional Test Applications
 241 ----------------------------
 242
 243 In addition, there are two other applications that are built when the libraries are created.
 244 The source files for these are in the DPDK/app directory and are called test and testpmd.
 245 Once the libraries are created, they can be found in the build/app directory.
 246
 247 *   The test application provides a variety of specific tests for the various functions in the DPDK.
 248
 249 *   The testpmd application provides a number of different packet throughput tests and
 250     examples of features such as how to use the Flow Director found in the Intel® 82599 10 Gigabit Ethernet Controller.