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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 2cd0e3b3e1fd
children
rev   line source
Chris@42 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
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Chris@42 6 Copyright (C) 2003 Matteo Frigo.
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Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Avoiding MPI Deadlocks</title>
Chris@42 26
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Chris@42 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" rel="up" title="Distributed-memory FFTW with MPI">
Chris@42 37 <link href="FFTW-MPI-Performance-Tips.html#FFTW-MPI-Performance-Tips" rel="next" title="FFTW MPI Performance Tips">
Chris@42 38 <link href="FFTW-MPI-Wisdom.html#FFTW-MPI-Wisdom" rel="prev" title="FFTW MPI Wisdom">
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Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Avoiding-MPI-Deadlocks"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Next: <a href="FFTW-MPI-Performance-Tips.html#FFTW-MPI-Performance-Tips" accesskey="n" rel="next">FFTW MPI Performance Tips</a>, Previous: <a href="FFTW-MPI-Wisdom.html#FFTW-MPI-Wisdom" accesskey="p" rel="prev">FFTW MPI Wisdom</a>, Up: <a href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" accesskey="u" rel="up">Distributed-memory FFTW with MPI</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>
Chris@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Avoiding-MPI-Deadlocks-1"></a>
Chris@42 79 <h3 class="section">6.9 Avoiding MPI Deadlocks</h3>
Chris@42 80 <a name="index-deadlock"></a>
Chris@42 81
Chris@42 82 <p>An MPI program can <em>deadlock</em> if one process is waiting for a
Chris@42 83 message from another process that never gets sent. To avoid deadlocks
Chris@42 84 when using FFTW&rsquo;s MPI routines, it is important to know which
Chris@42 85 functions are <em>collective</em>: that is, which functions must
Chris@42 86 <em>always</em> be called in the <em>same order</em> from <em>every</em>
Chris@42 87 process in a given communicator. (For example, <code>MPI_Barrier</code> is
Chris@42 88 the canonical example of a collective function in the MPI standard.)
Chris@42 89 <a name="index-collective-function-2"></a>
Chris@42 90 <a name="index-MPI_005fBarrier"></a>
Chris@42 91 </p>
Chris@42 92
Chris@42 93 <p>The functions in FFTW that are <em>always</em> collective are: every
Chris@42 94 function beginning with &lsquo;<samp>fftw_mpi_plan</samp>&rsquo;, as well as
Chris@42 95 <code>fftw_mpi_broadcast_wisdom</code> and <code>fftw_mpi_gather_wisdom</code>.
Chris@42 96 Also, the following functions from the ordinary FFTW interface are
Chris@42 97 collective when they are applied to a plan created by an
Chris@42 98 &lsquo;<samp>fftw_mpi_plan</samp>&rsquo; function: <code>fftw_execute</code>,
Chris@42 99 <code>fftw_destroy_plan</code>, and <code>fftw_flops</code>.
Chris@42 100 <a name="index-fftw_005fexecute-4"></a>
Chris@42 101 <a name="index-fftw_005fdestroy_005fplan-2"></a>
Chris@42 102 <a name="index-fftw_005fflops-1"></a>
Chris@42 103 </p>
Chris@42 104
Chris@42 105
Chris@42 106
Chris@42 107 </body>
Chris@42 108 </html>