annotate fft/fftw/fftw-3.3.4/doc/html/Multi_002dthreaded-FFTW.html @ 40:223f770b5341 kissfft-double tip

Try a double-precision kissfft
author Chris Cannam
date Wed, 07 Sep 2016 10:40:32 +0100
parents 26056e866c29
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Chris@19 3 <title>Multi-threaded FFTW - FFTW 3.3.4</title>
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Chris@19 50 <p>
Chris@19 51 Next:&nbsp;<a rel="next" accesskey="n" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI">Distributed-memory FFTW with MPI</a>,
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Chris@19 53 Up:&nbsp;<a rel="up" accesskey="u" href="index.html#Top">Top</a>
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Chris@19 56
Chris@19 57 <h2 class="chapter">5 Multi-threaded FFTW</h2>
Chris@19 58
Chris@19 59 <p><a name="index-parallel-transform-329"></a>In this chapter we document the parallel FFTW routines for
Chris@19 60 shared-memory parallel hardware. These routines, which support
Chris@19 61 parallel one- and multi-dimensional transforms of both real and
Chris@19 62 complex data, are the easiest way to take advantage of multiple
Chris@19 63 processors with FFTW. They work just like the corresponding
Chris@19 64 uniprocessor transform routines, except that you have an extra
Chris@19 65 initialization routine to call, and there is a routine to set the
Chris@19 66 number of threads to employ. Any program that uses the uniprocessor
Chris@19 67 FFTW can therefore be trivially modified to use the multi-threaded
Chris@19 68 FFTW.
Chris@19 69
Chris@19 70 <p>A shared-memory machine is one in which all CPUs can directly access
Chris@19 71 the same main memory, and such machines are now common due to the
Chris@19 72 ubiquity of multi-core CPUs. FFTW's multi-threading support allows
Chris@19 73 you to utilize these additional CPUs transparently from a single
Chris@19 74 program. However, this does not necessarily translate into
Chris@19 75 performance gains&mdash;when multiple threads/CPUs are employed, there is
Chris@19 76 an overhead required for synchronization that may outweigh the
Chris@19 77 computatational parallelism. Therefore, you can only benefit from
Chris@19 78 threads if your problem is sufficiently large.
Chris@19 79 <a name="index-shared_002dmemory-330"></a><a name="index-threads-331"></a>
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Chris@19 81 <ul class="menu">
Chris@19 82 <li><a accesskey="1" href="Installation-and-Supported-Hardware_002fSoftware.html#Installation-and-Supported-Hardware_002fSoftware">Installation and Supported Hardware/Software</a>
Chris@19 83 <li><a accesskey="2" href="Usage-of-Multi_002dthreaded-FFTW.html#Usage-of-Multi_002dthreaded-FFTW">Usage of Multi-threaded FFTW</a>
Chris@19 84 <li><a accesskey="3" href="How-Many-Threads-to-Use_003f.html#How-Many-Threads-to-Use_003f">How Many Threads to Use?</a>
Chris@19 85 <li><a accesskey="4" href="Thread-safety.html#Thread-safety">Thread safety</a>
Chris@19 86 </ul>
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