mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-01 18:42:40 +00:00
151 lines
8.2 KiB
HTML
151 lines
8.2 KiB
HTML
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- This manual is for FFTW
|
||
|
|
(version 3.3.10, 10 December 2020).
|
||
|
|
|
||
|
|
Copyright (C) 2003 Matteo Frigo.
|
||
|
|
|
||
|
|
Copyright (C) 2003 Massachusetts Institute of Technology.
|
||
|
|
|
||
|
|
Permission is granted to make and distribute verbatim copies of this
|
||
|
|
manual provided the copyright notice and this permission notice are
|
||
|
|
preserved on all copies.
|
||
|
|
|
||
|
|
Permission is granted to copy and distribute modified versions of this
|
||
|
|
manual under the conditions for verbatim copying, provided that the
|
||
|
|
entire resulting derived work is distributed under the terms of a
|
||
|
|
permission notice identical to this one.
|
||
|
|
|
||
|
|
Permission is granted to copy and distribute translations of this manual
|
||
|
|
into another language, under the above conditions for modified versions,
|
||
|
|
except that this permission notice may be stated in a translation
|
||
|
|
approved by the Free Software Foundation. -->
|
||
|
|
<!-- Created by GNU Texinfo 6.7, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
||
|
|
<title>Distributed-memory FFTW with MPI (FFTW 3.3.10)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Distributed-memory FFTW with MPI (FFTW 3.3.10)">
|
||
|
|
<meta name="keywords" content="Distributed-memory FFTW with MPI (FFTW 3.3.10)">
|
||
|
|
<meta name="resource-type" content="document">
|
||
|
|
<meta name="distribution" content="global">
|
||
|
|
<meta name="Generator" content="makeinfo">
|
||
|
|
<link href="index.html" rel="start" title="Top">
|
||
|
|
<link href="Concept-Index.html" rel="index" title="Concept Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="index.html" rel="up" title="Top">
|
||
|
|
<link href="FFTW-MPI-Installation.html" rel="next" title="FFTW MPI Installation">
|
||
|
|
<link href="Thread-safety.html" rel="prev" title="Thread safety">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.indentedblock {margin-right: 0em}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
kbd {font-style: oblique}
|
||
|
|
pre.display {font-family: inherit}
|
||
|
|
pre.format {font-family: inherit}
|
||
|
|
pre.menu-comment {font-family: serif}
|
||
|
|
pre.menu-preformatted {font-family: serif}
|
||
|
|
span.nolinebreak {white-space: nowrap}
|
||
|
|
span.roman {font-family: initial; font-weight: normal}
|
||
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en">
|
||
|
|
<span id="Distributed_002dmemory-FFTW-with-MPI"></span><div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Calling-FFTW-from-Modern-Fortran.html" accesskey="n" rel="next">Calling FFTW from Modern Fortran</a>, Previous: <a href="Multi_002dthreaded-FFTW.html" accesskey="p" rel="prev">Multi-threaded FFTW</a>, Up: <a href="index.html" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<span id="Distributed_002dmemory-FFTW-with-MPI-1"></span><h2 class="chapter">6 Distributed-memory FFTW with MPI</h2>
|
||
|
|
<span id="index-MPI"></span>
|
||
|
|
|
||
|
|
<span id="index-parallel-transform-1"></span>
|
||
|
|
<p>In this chapter we document the parallel FFTW routines for parallel
|
||
|
|
systems supporting the MPI message-passing interface. Unlike the
|
||
|
|
shared-memory threads described in the previous chapter, MPI allows
|
||
|
|
you to use <em>distributed-memory</em> parallelism, where each CPU has
|
||
|
|
its own separate memory, and which can scale up to clusters of many
|
||
|
|
thousands of processors. This capability comes at a price, however:
|
||
|
|
each process only stores a <em>portion</em> of the data to be
|
||
|
|
transformed, which means that the data structures and
|
||
|
|
programming-interface are quite different from the serial or threads
|
||
|
|
versions of FFTW.
|
||
|
|
<span id="index-data-distribution"></span>
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>Distributed-memory parallelism is especially useful when you are
|
||
|
|
transforming arrays so large that they do not fit into the memory of a
|
||
|
|
single processor. The storage per-process required by FFTW’s MPI
|
||
|
|
routines is proportional to the total array size divided by the number
|
||
|
|
of processes. Conversely, distributed-memory parallelism can easily
|
||
|
|
pose an unacceptably high communications overhead for small problems;
|
||
|
|
the threshold problem size for which parallelism becomes advantageous
|
||
|
|
will depend on the precise problem you are interested in, your
|
||
|
|
hardware, and your MPI implementation.
|
||
|
|
</p>
|
||
|
|
<p>A note on terminology: in MPI, you divide the data among a set of
|
||
|
|
“processes” which each run in their own memory address space.
|
||
|
|
Generally, each process runs on a different physical processor, but
|
||
|
|
this is not required. A set of processes in MPI is described by an
|
||
|
|
opaque data structure called a “communicator,” the most common of
|
||
|
|
which is the predefined communicator <code>MPI_COMM_WORLD</code> which
|
||
|
|
refers to <em>all</em> processes. For more information on these and
|
||
|
|
other concepts common to all MPI programs, we refer the reader to the
|
||
|
|
documentation at <a href="http://www.mcs.anl.gov/research/projects/mpi/">the MPI home
|
||
|
|
page</a>.
|
||
|
|
<span id="index-MPI-communicator"></span>
|
||
|
|
<span id="index-MPI_005fCOMM_005fWORLD"></span>
|
||
|
|
</p>
|
||
|
|
|
||
|
|
<p>We assume in this chapter that the reader is familiar with the usage
|
||
|
|
of the serial (uniprocessor) FFTW, and focus only on the concepts new
|
||
|
|
to the MPI interface.
|
||
|
|
</p>
|
||
|
|
<table class="menu" border="0" cellspacing="0">
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Installation.html" accesskey="1">FFTW MPI Installation</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Linking-and-Initializing-MPI-FFTW.html" accesskey="2">Linking and Initializing MPI FFTW</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="2d-MPI-example.html" accesskey="3">2d MPI example</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="MPI-Data-Distribution.html" accesskey="4">MPI Data Distribution</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html" accesskey="5">Multi-dimensional MPI DFTs of Real Data</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html" accesskey="6">Other Multi-dimensional Real-data MPI Transforms</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Transposes.html" accesskey="7">FFTW MPI Transposes</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Wisdom.html" accesskey="8">FFTW MPI Wisdom</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Avoiding-MPI-Deadlocks.html" accesskey="9">Avoiding MPI Deadlocks</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Performance-Tips.html">FFTW MPI Performance Tips</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="Combining-MPI-and-Threads.html">Combining MPI and Threads</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Reference.html">FFTW MPI Reference</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
<tr><td align="left" valign="top">• <a href="FFTW-MPI-Fortran-Interface.html">FFTW MPI Fortran Interface</a></td><td> </td><td align="left" valign="top">
|
||
|
|
</td></tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Calling-FFTW-from-Modern-Fortran.html" accesskey="n" rel="next">Calling FFTW from Modern Fortran</a>, Previous: <a href="Multi_002dthreaded-FFTW.html" accesskey="p" rel="prev">Multi-threaded FFTW</a>, Up: <a href="index.html" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|