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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
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3 <!-- This manual is for FFTW
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6 Copyright (C) 2003 Matteo Frigo.
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25 <title>FFTW 3.3.8: Distributed-memory FFTW with MPI</title>
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37 <link href="FFTW-MPI-Installation.html#FFTW-MPI-Installation" rel="next" title="FFTW MPI Installation">
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71 <a name="Distributed_002dmemory-FFTW-with-MPI"></a>
72 <div class="header">
73 <p>
74 Next: <a href="Calling-FFTW-from-Modern-Fortran.html#Calling-FFTW-from-Modern-Fortran" accesskey="n" rel="next">Calling FFTW from Modern Fortran</a>, Previous: <a href="Multi_002dthreaded-FFTW.html#Multi_002dthreaded-FFTW" accesskey="p" rel="prev">Multi-threaded FFTW</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
75 </div>
76 <hr>
77 <a name="Distributed_002dmemory-FFTW-with-MPI-1"></a>
78 <h2 class="chapter">6 Distributed-memory FFTW with MPI</h2>
79 <a name="index-MPI"></a>
80
81 <a name="index-parallel-transform-1"></a>
82 <p>In this chapter we document the parallel FFTW routines for parallel
83 systems supporting the MPI message-passing interface. Unlike the
84 shared-memory threads described in the previous chapter, MPI allows
85 you to use <em>distributed-memory</em> parallelism, where each CPU has
86 its own separate memory, and which can scale up to clusters of many
87 thousands of processors. This capability comes at a price, however:
88 each process only stores a <em>portion</em> of the data to be
89 transformed, which means that the data structures and
90 programming-interface are quite different from the serial or threads
91 versions of FFTW.
92 <a name="index-data-distribution"></a>
93 </p>
94
95 <p>Distributed-memory parallelism is especially useful when you are
96 transforming arrays so large that they do not fit into the memory of a
97 single processor. The storage per-process required by FFTW&rsquo;s MPI
98 routines is proportional to the total array size divided by the number
99 of processes. Conversely, distributed-memory parallelism can easily
100 pose an unacceptably high communications overhead for small problems;
101 the threshold problem size for which parallelism becomes advantageous
102 will depend on the precise problem you are interested in, your
103 hardware, and your MPI implementation.
104 </p>
105 <p>A note on terminology: in MPI, you divide the data among a set of
106 &ldquo;processes&rdquo; which each run in their own memory address space.
107 Generally, each process runs on a different physical processor, but
108 this is not required. A set of processes in MPI is described by an
109 opaque data structure called a &ldquo;communicator,&rdquo; the most common of
110 which is the predefined communicator <code>MPI_COMM_WORLD</code> which
111 refers to <em>all</em> processes. For more information on these and
112 other concepts common to all MPI programs, we refer the reader to the
113 documentation at <a href="http://www.mcs.anl.gov/research/projects/mpi/">the MPI home
114 page</a>.
115 <a name="index-MPI-communicator"></a>
116 <a name="index-MPI_005fCOMM_005fWORLD"></a>
117 </p>
118
119 <p>We assume in this chapter that the reader is familiar with the usage
120 of the serial (uniprocessor) FFTW, and focus only on the concepts new
121 to the MPI interface.
122 </p>
123 <table class="menu" border="0" cellspacing="0">
124 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Installation.html#FFTW-MPI-Installation" accesskey="1">FFTW MPI Installation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
125 </td></tr>
126 <tr><td align="left" valign="top">&bull; <a href="Linking-and-Initializing-MPI-FFTW.html#Linking-and-Initializing-MPI-FFTW" accesskey="2">Linking and Initializing MPI FFTW</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
127 </td></tr>
128 <tr><td align="left" valign="top">&bull; <a href="2d-MPI-example.html#g_t2d-MPI-example" accesskey="3">2d MPI example</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
129 </td></tr>
130 <tr><td align="left" valign="top">&bull; <a href="MPI-Data-Distribution.html#MPI-Data-Distribution" accesskey="4">MPI Data Distribution</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
131 </td></tr>
132 <tr><td align="left" valign="top">&bull; <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data" accesskey="5">Multi-dimensional MPI DFTs of Real Data</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
133 </td></tr>
134 <tr><td align="left" valign="top">&bull; <a href="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html#Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms" accesskey="6">Other Multi-dimensional Real-data MPI Transforms</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
135 </td></tr>
136 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="7">FFTW MPI Transposes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
137 </td></tr>
138 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Wisdom.html#FFTW-MPI-Wisdom" accesskey="8">FFTW MPI Wisdom</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
139 </td></tr>
140 <tr><td align="left" valign="top">&bull; <a href="Avoiding-MPI-Deadlocks.html#Avoiding-MPI-Deadlocks" accesskey="9">Avoiding MPI Deadlocks</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
141 </td></tr>
142 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Performance-Tips.html#FFTW-MPI-Performance-Tips">FFTW MPI Performance Tips</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
143 </td></tr>
144 <tr><td align="left" valign="top">&bull; <a href="Combining-MPI-and-Threads.html#Combining-MPI-and-Threads">Combining MPI and Threads</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
145 </td></tr>
146 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference">FFTW MPI Reference</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
147 </td></tr>
148 <tr><td align="left" valign="top">&bull; <a href="FFTW-MPI-Fortran-Interface.html#FFTW-MPI-Fortran-Interface">FFTW MPI Fortran Interface</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
149 </td></tr>
150 </table>
151
152 <hr>
153 <div class="header">
154 <p>
155 Next: <a href="Calling-FFTW-from-Modern-Fortran.html#Calling-FFTW-from-Modern-Fortran" accesskey="n" rel="next">Calling FFTW from Modern Fortran</a>, Previous: <a href="Multi_002dthreaded-FFTW.html#Multi_002dthreaded-FFTW" accesskey="p" rel="prev">Multi-threaded FFTW</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
156 </div>
157
158
159
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