1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
<!DOCTYPE html>
<html class="writer-html5" lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>11.1. Environment variables set for MPI applications — Open MPI 5.0.8 documentation</title>
<link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
<link rel="stylesheet" type="text/css" href="../_static/css/theme.css" />
<!--[if lt IE 9]>
<script src="../_static/js/html5shiv.min.js"></script>
<![endif]-->
<script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script>
<script src="../_static/jquery.js"></script>
<script src="../_static/underscore.js"></script>
<script src="../_static/_sphinx_javascript_frameworks_compat.js"></script>
<script src="../_static/doctools.js"></script>
<script src="../_static/sphinx_highlight.js"></script>
<script src="../_static/js/theme.js"></script>
<link rel="index" title="Index" href="../genindex.html" />
<link rel="search" title="Search" href="../search.html" />
<link rel="next" title="11.2. Networking support" href="networking/index.html" />
<link rel="prev" title="11. Run-time operation and tuning MPI applications" href="index.html" />
</head>
<body class="wy-body-for-nav">
<div class="wy-grid-for-nav">
<nav data-toggle="wy-nav-shift" class="wy-nav-side">
<div class="wy-side-scroll">
<div class="wy-side-nav-search" >
<a href="../index.html" class="icon icon-home">
Open MPI
</a>
<div role="search">
<form id="rtd-search-form" class="wy-form" action="../search.html" method="get">
<input type="text" name="q" placeholder="Search docs" aria-label="Search docs" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div><div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="Navigation menu">
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../quickstart.html">1. Quick start</a></li>
<li class="toctree-l1"><a class="reference internal" href="../getting-help.html">2. Getting help</a></li>
<li class="toctree-l1"><a class="reference internal" href="../release-notes/index.html">3. Release notes</a></li>
<li class="toctree-l1"><a class="reference internal" href="../installing-open-mpi/index.html">4. Building and installing Open MPI</a></li>
<li class="toctree-l1"><a class="reference internal" href="../features/index.html">5. Open MPI-specific features</a></li>
<li class="toctree-l1"><a class="reference internal" href="../validate.html">6. Validating your installation</a></li>
<li class="toctree-l1"><a class="reference internal" href="../version-numbering.html">7. Version numbers and compatibility</a></li>
<li class="toctree-l1"><a class="reference internal" href="../mca.html">8. The Modular Component Architecture (MCA)</a></li>
<li class="toctree-l1"><a class="reference internal" href="../building-apps/index.html">9. Building MPI applications</a></li>
<li class="toctree-l1"><a class="reference internal" href="../launching-apps/index.html">10. Launching MPI applications</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="index.html">11. Run-time operation and tuning MPI applications</a><ul class="current">
<li class="toctree-l2 current"><a class="current reference internal" href="#">11.1. Environment variables set for MPI applications</a></li>
<li class="toctree-l2"><a class="reference internal" href="networking/index.html">11.2. Networking support</a></li>
<li class="toctree-l2"><a class="reference internal" href="multithreaded.html">11.3. Running multi-threaded MPI applications</a></li>
<li class="toctree-l2"><a class="reference internal" href="dynamic-loading.html">11.4. Dynamically loading <code class="docutils literal notranslate"><span class="pre">libmpi</span></code> at runtime</a></li>
<li class="toctree-l2"><a class="reference internal" href="fork-system-popen.html">11.5. Calling fork(), system(), or popen() in MPI processes</a></li>
<li class="toctree-l2"><a class="reference internal" href="fault-tolerance/index.html">11.6. Fault tolerance</a></li>
<li class="toctree-l2"><a class="reference internal" href="large-clusters/index.html">11.7. Large Clusters</a></li>
<li class="toctree-l2"><a class="reference internal" href="affinity.html">11.8. Processor and memory affinity</a></li>
<li class="toctree-l2"><a class="reference internal" href="mpi-io/index.html">11.9. MPI-IO tuning options</a></li>
<li class="toctree-l2"><a class="reference internal" href="coll-tuned.html">11.10. Tuning Collectives</a></li>
<li class="toctree-l2"><a class="reference internal" href="benchmarking.html">11.11. Benchmarking Open MPI applications</a></li>
<li class="toctree-l2"><a class="reference internal" href="heterogeneity.html">11.12. Building heterogeneous MPI applications</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../app-debug/index.html">12. Debugging Open MPI Parallel Applications</a></li>
<li class="toctree-l1"><a class="reference internal" href="../developers/index.html">13. Developer’s guide</a></li>
<li class="toctree-l1"><a class="reference internal" href="../contributing.html">14. Contributing to Open MPI</a></li>
<li class="toctree-l1"><a class="reference internal" href="../license/index.html">15. License</a></li>
<li class="toctree-l1"><a class="reference internal" href="../history.html">16. History of Open MPI</a></li>
<li class="toctree-l1"><a class="reference internal" href="../man-openmpi/index.html">17. Open MPI manual pages</a></li>
<li class="toctree-l1"><a class="reference internal" href="../man-openshmem/index.html">18. OpenSHMEM manual pages</a></li>
</ul>
</div>
</div>
</nav>
<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"><nav class="wy-nav-top" aria-label="Mobile navigation menu" >
<i data-toggle="wy-nav-top" class="fa fa-bars"></i>
<a href="../index.html">Open MPI</a>
</nav>
<div class="wy-nav-content">
<div class="rst-content">
<div role="navigation" aria-label="Page navigation">
<ul class="wy-breadcrumbs">
<li><a href="../index.html" class="icon icon-home" aria-label="Home"></a></li>
<li class="breadcrumb-item"><a href="index.html"><span class="section-number">11. </span>Run-time operation and tuning MPI applications</a></li>
<li class="breadcrumb-item active"><span class="section-number">11.1. </span>Environment variables set for MPI applications</li>
<li class="wy-breadcrumbs-aside">
<a href="../_sources/tuning-apps/environment-var.rst.txt" rel="nofollow"> View page source</a>
</li>
</ul>
<hr/>
</div>
<div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
<div itemprop="articleBody">
<style>
.wy-table-responsive table td,.wy-table-responsive table th{white-space:normal}
</style><div class="section" id="environment-variables-set-for-mpi-applications">
<h1><span class="section-number">11.1. </span>Environment variables set for MPI applications<a class="headerlink" href="#environment-variables-set-for-mpi-applications" title="Permalink to this heading"></a></h1>
<p>Open MPI provides the following environment variables that will be
defined on every MPI process:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_COMM_WORLD_SIZE</span></code>: the number of processes in this process’s
MPI_COMM_WORLD</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_COMM_WORLD_RANK</span></code>: the MPI rank of this process in
MPI_COMM_WORLD</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_COMM_WORLD_LOCAL_SIZE</span></code>: the number of ranks from this job
that are running on this node.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_COMM_WORLD_LOCAL_RANK</span></code>: the relative rank of this process on
this node within its job. For example, if four processes in a job
share a node, they will each be given a local rank ranging from 0 to
3.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_UNIVERSE_SIZE</span></code>: the number of <a class="reference internal" href="../launching-apps/scheduling.html#running-scheduling-slots-label"><span class="std std-ref">process slots</span></a> allocated to this job. Note that
this may be different than the number of processes in the job.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">OMPI_COMM_WORLD_NODE_RANK</span></code>: the relative rank of this process on
this node looking across <em>all</em> jobs.</p></li>
</ul>
</div>
</div>
</div>
<footer><div class="rst-footer-buttons" role="navigation" aria-label="Footer">
<a href="index.html" class="btn btn-neutral float-left" title="11. Run-time operation and tuning MPI applications" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a>
<a href="networking/index.html" class="btn btn-neutral float-right" title="11.2. Networking support" accesskey="n" rel="next">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
</div>
<hr/>
<div role="contentinfo">
<p>© Copyright 2003-2025, The Open MPI Community.
<span class="lastupdated">Last updated on 2025-05-30 16:41:43 UTC.
</span></p>
</div>
Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a
<a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a>
provided by <a href="https://readthedocs.org">Read the Docs</a>.
</footer>
</div>
</div>
</section>
</div>
<script>
jQuery(function () {
SphinxRtdTheme.Navigation.enable(true);
});
</script>
</body>
</html>
|
