xref: /dpdk/doc/guides/linux_gsg/build_sample_apps.rst (revision 35b09d76f89e7d5a4f38a2926cf6915028ed1e56)
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30
31Compiling and Running Sample Applications
32=========================================
33
34The chapter describes how to compile and run applications in an DPDK environment.
35It also provides a pointer to where sample applications are stored.
36
37.. note::
38
39    Parts of this process can also be done using the setup script described the
40    :ref:`linux_setup_script` section of this document.
41
42Compiling a Sample Application
43------------------------------
44
45Once an DPDK target environment directory has been created (such as ``x86_64-native-linuxapp-gcc``),
46it contains all libraries and header files required to build an application.
47
48When compiling an application in the Linux* environment on the DPDK, the following variables must be exported:
49
50* ``RTE_SDK`` - Points to the DPDK installation directory.
51
52* ``RTE_TARGET`` - Points to the DPDK target environment directory.
53
54The following is an example of creating the ``helloworld`` application, which runs in the DPDK Linux environment.
55This example may be found in the ``${RTE_SDK}/examples`` directory.
56
57The directory contains the ``main.c`` file. This file, when combined with the libraries in the DPDK target environment,
58calls the various functions to initialize the DPDK environment,
59then launches an entry point (dispatch application) for each core to be utilized.
60By default, the binary is generated in the build directory.
61
62.. code-block:: console
63
64    cd examples/helloworld/
65    export RTE_SDK=$HOME/DPDK
66    export RTE_TARGET=x86_64-native-linuxapp-gcc
67
68    make
69        CC main.o
70        LD helloworld
71        INSTALL-APP helloworld
72        INSTALL-MAP helloworld.map
73
74    ls build/app
75        helloworld helloworld.map
76
77.. note::
78
79    In the above example, ``helloworld`` was in the directory structure of the DPDK.
80    However, it could have been located outside the directory structure to keep the DPDK structure intact.
81    In the following case, the ``helloworld`` application is copied to a new directory as a new starting point.
82
83    .. code-block:: console
84
85       export RTE_SDK=/home/user/DPDK
86       cp -r $(RTE_SDK)/examples/helloworld my_rte_app
87       cd my_rte_app/
88       export RTE_TARGET=x86_64-native-linuxapp-gcc
89
90       make
91         CC main.o
92         LD helloworld
93         INSTALL-APP helloworld
94         INSTALL-MAP helloworld.map
95
96Running a Sample Application
97----------------------------
98
99.. warning::
100
101    The UIO drivers and hugepages must be setup prior to running an application.
102
103.. warning::
104
105    Any ports to be used by the application must be already bound to an appropriate kernel
106    module, as described in :ref:`linux_gsg_binding_kernel`, prior to running the application.
107
108The application is linked with the DPDK target environment's Environmental Abstraction Layer (EAL) library,
109which provides some options that are generic to every DPDK application.
110
111The following is the list of options that can be given to the EAL:
112
113.. code-block:: console
114
115    ./rte-app [-c COREMASK | -l CORELIST] [-n NUM] [-b <domain:bus:devid.func>] \
116              [--socket-mem=MB,...] [-m MB] [-r NUM] [-v] [--file-prefix] \
117	      [--proc-type <primary|secondary|auto>] [-- xen-dom0]
118
119The EAL options are as follows:
120
121* ``-c COREMASK`` or ``-l CORELIST``:
122  An hexadecimal bit mask of the cores to run on. Note that core numbering can
123  change between platforms and should be determined beforehand. The corelist is
124  a set of core numbers instead of a bitmap core mask.
125
126* ``-n NUM``:
127  Number of memory channels per processor socket.
128
129* ``-b <domain:bus:devid.func>``:
130  Blacklisting of ports; prevent EAL from using specified PCI device
131  (multiple ``-b`` options are allowed).
132
133* ``--use-device``:
134  use the specified Ethernet device(s) only. Use comma-separate
135  ``[domain:]bus:devid.func`` values. Cannot be used with ``-b`` option.
136
137* ``--socket-mem``:
138  Memory to allocate from hugepages on specific sockets.
139
140* ``-m MB``:
141  Memory to allocate from hugepages, regardless of processor socket. It is
142  recommended that ``--socket-mem`` be used instead of this option.
143
144* ``-r NUM``:
145  Number of memory ranks.
146
147* ``-v``:
148  Display version information on startup.
149
150* ``--huge-dir``:
151  The directory where hugetlbfs is mounted.
152
153* ``--file-prefix``:
154  The prefix text used for hugepage filenames.
155
156* ``--proc-type``:
157  The type of process instance.
158
159* ``--xen-dom0``:
160  Support application running on Xen Domain0 without hugetlbfs.
161
162* ``--vmware-tsc-map``:
163  Use VMware TSC map instead of native RDTSC.
164
165* ``--base-virtaddr``:
166  Specify base virtual address.
167
168* ``--vfio-intr``:
169  Specify interrupt type to be used by VFIO (has no effect if VFIO is not used).
170
171The ``-c`` or ``-l`` and option is mandatory; the others are optional.
172
173Copy the DPDK application binary to your target, then run the application as follows
174(assuming the platform has four memory channels per processor socket,
175and that cores 0-3 are present and are to be used for running the application)::
176
177    ./helloworld -l 0-3 -n 4
178
179.. note::
180
181    The ``--proc-type`` and ``--file-prefix`` EAL options are used for running
182    multiple DPDK processes. See the "Multi-process Sample Application"
183    chapter in the *DPDK Sample Applications User Guide* and the *DPDK
184    Programmers Guide* for more details.
185
186Logical Core Use by Applications
187~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
188
189The coremask (-c 0x0f) or corelist (-l 0-3) parameter is always mandatory for DPDK applications.
190Each 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.
191Since these logical core numbers, and their mapping to specific cores on specific NUMA sockets, can vary from platform to platform,
192it is recommended that the core layout for each platform be considered when choosing the coremask/corelist to use in each case.
193
194On initialization of the EAL layer by an DPDK application, the logical cores to be used and their socket location are displayed.
195This information can also be determined for all cores on the system by examining the ``/proc/cpuinfo`` file, for example, by running cat ``/proc/cpuinfo``.
196The physical id attribute listed for each processor indicates the CPU socket to which it belongs.
197This can be useful when using other processors to understand the mapping of the logical cores to the sockets.
198
199.. note::
200
201    A more graphical view of the logical core layout may be obtained using the ``lstopo`` Linux utility.
202    On Fedora Linux, this may be installed and run using the following command::
203
204        sudo yum install hwloc
205        ./lstopo
206
207.. warning::
208
209    The logical core layout can change between different board layouts and should be checked before selecting an application coremask/corelist.
210
211Hugepage Memory Use by Applications
212~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
213
214When running an application, it is recommended to use the same amount of memory as that allocated for hugepages.
215This is done automatically by the DPDK application at startup,
216if no ``-m`` or ``--socket-mem`` parameter is passed to it when run.
217
218If more memory is requested by explicitly passing a ``-m`` or ``--socket-mem`` value, the application fails.
219However, 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.
220The reason is as follows.
221Suppose the system has 1024 reserved 2 MB pages in socket 0 and 1024 in socket 1.
222If the user requests 128 MB of memory, the 64 pages may not match the constraints:
223
224*   The hugepage memory by be given to the application by the kernel in socket 1 only.
225    In this case, if the application attempts to create an object, such as a ring or memory pool in socket 0, it fails.
226    To avoid this issue, it is recommended that the ``--socket-mem`` option be used instead of the ``-m`` option.
227
228*   These pages can be located anywhere in physical memory, and, although the DPDK EAL will attempt to allocate memory in contiguous blocks,
229    it is possible that the pages will not be contiguous. In this case, the application is not able to allocate big memory pools.
230
231The socket-mem option can be used to request specific amounts of memory for specific sockets.
232This is accomplished by supplying the ``--socket-mem`` flag followed by amounts of memory requested on each socket,
233for example, supply ``--socket-mem=0,512`` to try and reserve 512 MB for socket 1 only.
234Similarly, 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.
235No memory will be reserved on any CPU socket that is not explicitly referenced, for example, socket 3 in this case.
236If the DPDK cannot allocate enough memory on each socket, the EAL initialization fails.
237
238Additional Sample Applications
239------------------------------
240
241Additional sample applications are included in the ${RTE_SDK}/examples directory.
242These sample applications may be built and run in a manner similar to that described in earlier sections in this manual.
243In addition, see the *DPDK Sample Applications User Guide* for a description of the application,
244specific instructions on compilation and execution and some explanation of the code.
245
246Additional Test Applications
247----------------------------
248
249In addition, there are two other applications that are built when the libraries are created.
250The source files for these are in the DPDK/app directory and are called test and testpmd.
251Once the libraries are created, they can be found in the build/app directory.
252
253*   The test application provides a variety of specific tests for the various functions in the DPDK.
254
255*   The testpmd application provides a number of different packet throughput tests and
256    examples of features such as how to use the Flow Director found in the Intel® 82599 10 Gigabit Ethernet Controller.
257