Mercurial > hg > sv-dependency-builds
diff src/fftw-3.3.5/doc/html/Multi_002dthreaded-FFTW.html @ 127:7867fa7e1b6b
Current fftw source
| author | Chris Cannam <cannam@all-day-breakfast.com> |
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| date | Tue, 18 Oct 2016 13:40:26 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.5/doc/html/Multi_002dthreaded-FFTW.html Tue Oct 18 13:40:26 2016 +0100 @@ -0,0 +1,120 @@ +<!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 3.3.5, 30 July 2016). + +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 5.2, http://www.gnu.org/software/texinfo/ --> +<head> +<title>FFTW 3.3.5: Multi-threaded FFTW</title> + +<meta name="description" content="FFTW 3.3.5: Multi-threaded FFTW"> +<meta name="keywords" content="FFTW 3.3.5: Multi-threaded FFTW"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="index.html#Top" rel="up" title="Top"> +<link href="Installation-and-Supported-Hardware_002fSoftware.html#Installation-and-Supported-Hardware_002fSoftware" rel="next" title="Installation and Supported Hardware/Software"> +<link href="Multi_002ddimensional-Transforms.html#Multi_002ddimensional-Transforms" rel="prev" title="Multi-dimensional Transforms"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {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} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Multi_002dthreaded-FFTW"></a> +<div class="header"> +<p> +Next: <a href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" accesskey="n" rel="next">Distributed-memory FFTW with MPI</a>, Previous: <a href="FFTW-Reference.html#FFTW-Reference" accesskey="p" rel="prev">FFTW Reference</a>, Up: <a href="index.html#Top" 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#Concept-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Multi_002dthreaded-FFTW-1"></a> +<h2 class="chapter">5 Multi-threaded FFTW</h2> + +<a name="index-parallel-transform"></a> +<p>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> +<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"></a> +<a name="index-threads"></a> +</p> +<table class="menu" border="0" cellspacing="0"> +<tr><td align="left" valign="top">• <a href="Installation-and-Supported-Hardware_002fSoftware.html#Installation-and-Supported-Hardware_002fSoftware" accesskey="1">Installation and Supported Hardware/Software</a>:</td><td> </td><td align="left" valign="top"> +</td></tr> +<tr><td align="left" valign="top">• <a href="Usage-of-Multi_002dthreaded-FFTW.html#Usage-of-Multi_002dthreaded-FFTW" accesskey="2">Usage of Multi-threaded FFTW</a>:</td><td> </td><td align="left" valign="top"> +</td></tr> +<tr><td align="left" valign="top">• <a href="How-Many-Threads-to-Use_003f.html#How-Many-Threads-to-Use_003f" accesskey="3">How Many Threads to Use?</a>:</td><td> </td><td align="left" valign="top"> +</td></tr> +<tr><td align="left" valign="top">• <a href="Thread-safety.html#Thread-safety" accesskey="4">Thread safety</a>:</td><td> </td><td align="left" valign="top"> +</td></tr> +</table> + + + + +</body> +</html>