Mercurial > hg > sv-dependency-builds
diff src/fftw-3.3.3/doc/html/Multi_002dthreaded-FFTW.html @ 10:37bf6b4a2645
Add FFTW3
| author | Chris Cannam |
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| date | Wed, 20 Mar 2013 15:35:50 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.3/doc/html/Multi_002dthreaded-FFTW.html Wed Mar 20 15:35:50 2013 +0000 @@ -0,0 +1,90 @@ +<html lang="en"> +<head> +<title>Multi-threaded FFTW - FFTW 3.3.3</title> +<meta http-equiv="Content-Type" content="text/html"> +<meta name="description" content="FFTW 3.3.3"> +<meta name="generator" content="makeinfo 4.13"> +<link title="Top" rel="start" href="index.html#Top"> +<link rel="prev" href="FFTW-Reference.html#FFTW-Reference" title="FFTW Reference"> +<link rel="next" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" title="Distributed-memory FFTW with MPI"> +<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> +<!-- +This manual is for FFTW +(version 3.3.3, 25 November 2012). + +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. + --> +<meta http-equiv="Content-Style-Type" content="text/css"> +<style type="text/css"><!-- + pre.display { font-family:inherit } + pre.format { font-family:inherit } + pre.smalldisplay { font-family:inherit; font-size:smaller } + pre.smallformat { font-family:inherit; font-size:smaller } + pre.smallexample { font-size:smaller } + pre.smalllisp { font-size:smaller } + span.sc { font-variant:small-caps } + span.roman { font-family:serif; font-weight:normal; } + span.sansserif { font-family:sans-serif; font-weight:normal; } +--></style> +</head> +<body> +<div class="node"> +<a name="Multi-threaded-FFTW"></a> +<a name="Multi_002dthreaded-FFTW"></a> +<p> +Next: <a rel="next" accesskey="n" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI">Distributed-memory FFTW with MPI</a>, +Previous: <a rel="previous" accesskey="p" href="FFTW-Reference.html#FFTW-Reference">FFTW Reference</a>, +Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> +<hr> +</div> + +<h2 class="chapter">5 Multi-threaded FFTW</h2> + +<p><a name="index-parallel-transform-326"></a>In this chapter we document the parallel FFTW routines for +shared-memory parallel hardware. These routines, which support +parallel one- and multi-dimensional transforms of both real and +complex data, are the easiest way to take advantage of multiple +processors with FFTW. They work just like the corresponding +uniprocessor transform routines, except that you have an extra +initialization routine to call, and there is a routine to set the +number of threads to employ. Any program that uses the uniprocessor +FFTW can therefore be trivially modified to use the multi-threaded +FFTW. + + <p>A shared-memory machine is one in which all CPUs can directly access +the same main memory, and such machines are now common due to the +ubiquity of multi-core CPUs. FFTW's multi-threading support allows +you to utilize these additional CPUs transparently from a single +program. However, this does not necessarily translate into +performance gains—when multiple threads/CPUs are employed, there is +an overhead required for synchronization that may outweigh the +computatational parallelism. Therefore, you can only benefit from +threads if your problem is sufficiently large. +<a name="index-shared_002dmemory-327"></a><a name="index-threads-328"></a> + +<ul class="menu"> +<li><a accesskey="1" href="Installation-and-Supported-Hardware_002fSoftware.html#Installation-and-Supported-Hardware_002fSoftware">Installation and Supported Hardware/Software</a> +<li><a accesskey="2" href="Usage-of-Multi_002dthreaded-FFTW.html#Usage-of-Multi_002dthreaded-FFTW">Usage of Multi-threaded FFTW</a> +<li><a accesskey="3" href="How-Many-Threads-to-Use_003f.html#How-Many-Threads-to-Use_003f">How Many Threads to Use?</a> +<li><a accesskey="4" href="Thread-safety.html#Thread-safety">Thread safety</a> +</ul> + +<!-- --> + </body></html> +