Mercurial > hg > batch-feature-extraction-tool
diff Lib/fftw-3.2.1/doc/html/.svn/text-base/Thread-safety.html.svn-base @ 15:585caf503ef5 tip
Tidy up for ROLI
| author | Geogaddi\David <d.m.ronan@qmul.ac.uk> |
|---|---|
| date | Tue, 17 May 2016 18:50:19 +0100 |
| parents | 636c989477e7 |
| children |
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--- a/Lib/fftw-3.2.1/doc/html/.svn/text-base/Thread-safety.html.svn-base Wed May 04 11:02:59 2016 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,86 +0,0 @@ -<html lang="en"> -<head> -<title>Thread safety - FFTW 3.2.1</title> -<meta http-equiv="Content-Type" content="text/html"> -<meta name="description" content="FFTW 3.2.1"> -<meta name="generator" content="makeinfo 4.8"> -<link title="Top" rel="start" href="index.html#Top"> -<link rel="up" href="Multi_002dthreaded-FFTW.html#Multi_002dthreaded-FFTW" title="Multi-threaded FFTW"> -<link rel="prev" href="How-Many-Threads-to-Use_003f.html#How-Many-Threads-to-Use_003f" title="How Many Threads to Use?"> -<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> -<!-- -This manual is for FFTW -(version 3.2.1, 5 February 2009). - -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"> -<p> -<a name="Thread-safety"></a> -Previous: <a rel="previous" accesskey="p" href="How-Many-Threads-to-Use_003f.html#How-Many-Threads-to-Use_003f">How Many Threads to Use?</a>, -Up: <a rel="up" accesskey="u" href="Multi_002dthreaded-FFTW.html#Multi_002dthreaded-FFTW">Multi-threaded FFTW</a> -<hr> -</div> - -<h3 class="section">5.4 Thread safety</h3> - -<p><a name="index-threads-327"></a><a name="index-thread-safety-328"></a>Users writing multi-threaded programs must concern themselves with the -<dfn>thread safety</dfn> of the libraries they use—that is, whether it is -safe to call routines in parallel from multiple threads. FFTW can be -used in such an environment, but some care must be taken because the -planner routines share data (e.g. wisdom and trigonometric tables) -between calls and plans. - - <p>The upshot is that the only thread-safe (re-entrant) routine in FFTW is -<code>fftw_execute</code> (and the new-array variants thereof). All other routines -(e.g. the planner) should only be called from one thread at a time. So, -for example, you can wrap a semaphore lock around any calls to the -planner; even more simply, you can just create all of your plans from -one thread. We do not think this should be an important restriction -(FFTW is designed for the situation where the only performance-sensitive -code is the actual execution of the transform), and the benefits of -shared data between plans are great. - - <p>Note also that, since the plan is not modified by <code>fftw_execute</code>, -it is safe to execute the <em>same plan</em> in parallel by multiple -threads. However, since a given plan operates by default on a fixed -array, you need to use one of the new-array execute functions (see <a href="New_002darray-Execute-Functions.html#New_002darray-Execute-Functions">New-array Execute Functions</a>) so that different threads compute the transform of different data. - - <p>(Users should note that these comments only apply to programs using -shared-memory threads. Parallelism using MPI or forked processes -involves a separate address-space and global variables for each process, -and is not susceptible to problems of this sort.) - -<!-- ************************************************************ --> -</body></html> -