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| author | Chris Cannam |
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| date | Wed, 20 Mar 2013 15:35:50 +0000 |
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| 9:c0fb53affa76 | 10:37bf6b4a2645 |
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| 1 <html lang="en"> | |
| 2 <head> | |
| 3 <title>Multi-threaded FFTW - FFTW 3.3.3</title> | |
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| 5 <meta name="description" content="FFTW 3.3.3"> | |
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| 9 <link rel="next" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" title="Distributed-memory FFTW with MPI"> | |
| 10 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> | |
| 11 <!-- | |
| 12 This manual is for FFTW | |
| 13 (version 3.3.3, 25 November 2012). | |
| 14 | |
| 15 Copyright (C) 2003 Matteo Frigo. | |
| 16 | |
| 17 Copyright (C) 2003 Massachusetts Institute of Technology. | |
| 18 | |
| 19 Permission is granted to make and distribute verbatim copies of | |
| 20 this manual provided the copyright notice and this permission | |
| 21 notice are preserved on all copies. | |
| 22 | |
| 23 Permission is granted to copy and distribute modified versions of | |
| 24 this manual under the conditions for verbatim copying, provided | |
| 25 that the entire resulting derived work is distributed under the | |
| 26 terms of a permission notice identical to this one. | |
| 27 | |
| 28 Permission is granted to copy and distribute translations of this | |
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| 30 modified versions, except that this permission notice may be | |
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| 47 <div class="node"> | |
| 48 <a name="Multi-threaded-FFTW"></a> | |
| 49 <a name="Multi_002dthreaded-FFTW"></a> | |
| 50 <p> | |
| 51 Next: <a rel="next" accesskey="n" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI">Distributed-memory FFTW with MPI</a>, | |
| 52 Previous: <a rel="previous" accesskey="p" href="FFTW-Reference.html#FFTW-Reference">FFTW Reference</a>, | |
| 53 Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> | |
| 54 <hr> | |
| 55 </div> | |
| 56 | |
| 57 <h2 class="chapter">5 Multi-threaded FFTW</h2> | |
| 58 | |
| 59 <p><a name="index-parallel-transform-326"></a>In this chapter we document the parallel FFTW routines for | |
| 60 shared-memory parallel hardware. These routines, which support | |
| 61 parallel one- and multi-dimensional transforms of both real and | |
| 62 complex data, are the easiest way to take advantage of multiple | |
| 63 processors with FFTW. They work just like the corresponding | |
| 64 uniprocessor transform routines, except that you have an extra | |
| 65 initialization routine to call, and there is a routine to set the | |
| 66 number of threads to employ. Any program that uses the uniprocessor | |
| 67 FFTW can therefore be trivially modified to use the multi-threaded | |
| 68 FFTW. | |
| 69 | |
| 70 <p>A shared-memory machine is one in which all CPUs can directly access | |
| 71 the same main memory, and such machines are now common due to the | |
| 72 ubiquity of multi-core CPUs. FFTW's multi-threading support allows | |
| 73 you to utilize these additional CPUs transparently from a single | |
| 74 program. However, this does not necessarily translate into | |
| 75 performance gains—when multiple threads/CPUs are employed, there is | |
| 76 an overhead required for synchronization that may outweigh the | |
| 77 computatational parallelism. Therefore, you can only benefit from | |
| 78 threads if your problem is sufficiently large. | |
| 79 <a name="index-shared_002dmemory-327"></a><a name="index-threads-328"></a> | |
| 80 | |
| 81 <ul class="menu"> | |
| 82 <li><a accesskey="1" href="Installation-and-Supported-Hardware_002fSoftware.html#Installation-and-Supported-Hardware_002fSoftware">Installation and Supported Hardware/Software</a> | |
| 83 <li><a accesskey="2" href="Usage-of-Multi_002dthreaded-FFTW.html#Usage-of-Multi_002dthreaded-FFTW">Usage of Multi-threaded FFTW</a> | |
| 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> | |
| 85 <li><a accesskey="4" href="Thread-safety.html#Thread-safety">Thread safety</a> | |
| 86 </ul> | |
| 87 | |
| 88 <!-- --> | |
| 89 </body></html> | |
| 90 |