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<html>
<head>
<title>
OPENMP_STUBS - A C++ "Stub" Library for OpenMP
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
OPENMP_STUBS <br> A C++ "Stub" Library for OpenMP
</h1>
<hr>
<p>
<b>OPENMP_STUBS</b>
is a C++ library which
constitute a "stub" implementation of the OpenMP 2.5 standard.
</p>
<p>
A stub library is useful when you want to try out a program on a system
that does not have OpenMP, or when you need to have a formally complete
program to analyze, or in other cases where you want to ignore the actual
OpenMP library. A stub library can also help to understand the structure
of the actual library.
</p>
<h3 align = "center">
Licensing:
</h3>
<p>
The computer code and data files described and made available on this web page
are distributed under
<a href = "../../txt/gnu_lgpl.txt">the GNU LGPL license.</a>
</p>
<h3 align = "center">
Languages:
</h3>
<p>
<b>OPENMP_STUBS</b> is available in
<a href = "../../c_src/openmp_stubs/openmp_stubs.html">a C version</a> and
<a href = "../../cpp_src/openmp_stubs/openmp_stubs.html">a C++ version</a> and
<a href = "../../f77_src/openmp_stubs/openmp_stubs.html">a FORTRAN77 version</a> and
<a href = "../../f_src/openmp_stubs/openmp_stubs.html">a FORTRAN90 version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../cpp_src/dijkstra_openmp/dijkstra_openmp.html">
DIJKSTRA_OPENMP</a>,
a C++ program which
uses OpenMP to parallelize a simple example of Dijkstra's
minimum distance algorithm for graphs.
</p>
<p>
<a href = "../../cpp_src/fft_openmp/fft_openmp.html">
FFT_OPENMP</a>,
a C++ program which
demonstrates the computation of a Fast Fourier Transform
in parallel, using OpenMP.
</p>
<p>
<a href = "../../cpp_src/heated_plate_openmp/heated_plate_openmp.html">
HEATED_PLATE_OPENMP</a>,
a C++ program which
solves the steady (time independent) heat equation in a 2D
rectangular region, using OpenMP to run in parallel.
</p>
<p>
<a href = "../../cpp_src/hello_openmp/hello_openmp.html">
HELLO_OPENMP</a>,
a C++ program which
prints out "Hello, world!" using the OpenMP parallel programming environment.
</p>
<p>
<a href = "../../cpp_src/md_openmp/md_openmp.html">
MD_OPENMP</a>,
a C++ program which
carries out a molecular dynamics simulation using OpenMP.
<p>
<p>
<a href = "../../cpp_src/multitask_openmp/multitask_openmp.html">
MULTITASK_OPENMP</a>,
a C++ program which
demonstrates how to "multitask", that is, to execute several unrelated
and distinct tasks simultaneously, using OpenMP for parallel execution.
</p>
<p>
<a href = "../../cpp_src/mxv_openmp/mxv_openmp.html">
MXM_OPENMP</a>,
a C++ program which
computes a dense matrix product C=A*B,
using OpenMP for parallel execution.
<p>
<p>
<a href = "../../cpp_src/openmp/openmp.html">
OPENMP</a>,
C++ programs which
illustrate the use of OpenMP directives and function calls
to solve problems in parallel.
</p>
<p>
<a href = "../../cpp_src/prime_openmp/prime_openmp.html">
PRIME_OPENMP</a>,
a C++ program which
counts the number of primes between 1 and N, using OpenMP for parallel execution.
</p>
<p>
<a href = "../../cpp_src/quad_openmp/quad_openmp.html">
QUAD_OPENMP</a>,
a C++ program which
approximates an integral using a quadrature rule, and carries out the
computation in parallel using OpenMP.
</p>
<p>
<a href = "../../cpp_src/satisfy_openmp/satisfy_openmp.html">
SATISFY_OPENMP</a>,
a C++ program which
demonstrates, for a particular circuit, an exhaustive search
for solutions of the circuit satisfiability problem,
using OpenMP for parallel execution.
<p>
<p>
<a href = "../../cpp_src/schedule_openmp/schedule_openmp.html">
SCHEDULE_OPENMP</a>,
a C++ program which
demonstrates the default, static, and dynamic methods of "scheduling"
loop iterations in OpenMP to avoid work imbalance.
<p>
<p>
<a href = "../../cpp_src/sgefa_openmp/sgefa_openmp.html">
SGEFA_OPENMP</a>,
a C++ program which
reimplements the SGEFA/SGESL linear algebra routines from
LINPACK for use with OpenMP.
</p>
<p>
<a href = "../../cpp_src/ziggurat_openmp/ziggurat_openmp.html">
ZIGGURAT_OPENMP</a>,
a C++ program which
demonstrates how the ZIGGURAT library can be used to generate random numbers
in an OpenMP parallel program.
</p>
<h3 align = "center">
Reference:
</h3>
<p>
<ol>
<li>
Rohit Chandra, Leonardo Dagum, Dave Kohr, Dror Maydan,
Jeff McDonald, Ramesh Menon,<br>
Parallel Programming in OpenMP,<br>
Morgan Kaufmann, 2001,<br>
ISBN: 1-55860-671-8,<br>
LC: QA76.642.P32.
</li>
<li>
Barbara Chapman, Gabriele Jost, Ruud vanderPas, David Kuck,<br>
Using OpenMP: Portable Shared Memory Parallel Processing,<br>
MIT Press, 2007,<br>
ISBN13: 978-0262533027.
</li>
<li>
<a href = "http://www.openmp.org/">The OpenMP web site</a>
</li>
<li>
OpenMP Architecture Review Board,<br>
OpenMP Application Program Interface,<br>
Version 3.0,<br>
May 2008.
</li>
</ol>
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "openmp_stubs.cpp">openmp_stubs.cpp</a>, the source code.
</li>
<li>
<a href = "openmp_stubs.sh">openmp_stubs.sh</a>,
commands to compile the source code.
</li>
<li>
<a href = "openmp_stubs.hpp">openmp_stubs.hpp</a>,
a simple "include" file that declares the type of the
functions that are part of the library. An OpenMP code
will probably be looking for a file called "omp.h" instead.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<b>
Note that these examples are normally run in parallel with OpenMP.
The point being made here is that such programs can be run sequentially,
as though OpenMP were available, by calling the OPENMP_STUBS library.
They don't run well (fast) - it's just remarkable that they run at all.
</b>
</p>
<p>
<b>COMPUTE_PI</b> shows how information can be shared.
Several processors need to compute pieces of a sum that will
approximate pi.
<ul>
<li>
<a href = "../../cpp_src/openmp/compute_pi.cpp">compute_pi.cpp</a>,
the source code;
</li>
<li>
<a href = "compute_pi.sh">compute_pi.sh</a>,
BASH commands to compile, link, load and run the program
with the OPENMP_STUBS library.
</li>
<li>
<a href = "compute_pi_output.txt">compute_pi_output.txt</a>,
the output file;
</li>
</ul>
</p>
<p>
<b>HELLO</b> is a very simple program which calls an
OpenMP subroutine to set the number of threads, and then has
each thread say hello;
<ul>
<li>
<a href = "../../cpp_src/openmp/hello.cpp">hello.cpp</a>,
the source code;
</li>
<li>
<a href = "hello.sh">hello.sh</a>,
BASH commands to compile, link, load and run the program
with the OPENMP_STUBS library.
</li>
<li>
<a href = "hello_output.txt">hello_output.txt</a>,
the output file;
</li>
</ul>
</p>
<p>
<b>HELMHOLTZ</b> is a program that solves
the Helmholtz equation on a rectangular grid, using Jacobi iteration
with overrelaxation;
<ul>
<li>
<a href = "../../cpp_src/helmholtz.cpp">helmholtz.cpp</a>,
the source code;
</li>
<li>
BASH commands to compile, link, load and run the program
with the OPENMP_STUBS library.
</li>
<li>
<a href = "helmholtz_output.txt">helmholtz_output.txt</a>,
the output file;
</li>
</ul>
</p>
<h3 align = "center">
List of Routines:
</h3>
<p>
<b>
Again, please don't be confused. These routines have the same names
as the real OpenMP library; they just don't do anything. Well, not much,
anyway. They do just enough to let a program run in sequential mode.
</b>
</p>
<p>
<ul>
<li>
<b>OMP_DESTROY_LOCK</b> destroys a simple lock.
</li>
<li>
<b>OMP_DESTROY_NEST_LOCK</b> destroys a nestable lock.
</li>
<li>
<b>OMP_GET_DYNAMIC</b> reports if dynamic adjustment of thread number is allowed.
</li>
<li>
<b>OMP_GET_MAX_THREADS</b> returns the default number of threads.
</li>
<li>
<b>OMP_GET_NESTED</b> reports if nested parallelism has been enabled.
</li>
<li>
<b>OMP_GET_NUM_PROCS</b> returns the number of processors available to the program.
</li>
<li>
<b>OMP_GET_NUM_THREADS</b> returns the number of threads in the current team.
</li>
<li>
<b>OMP_GET_THREAD_NUM</b> returns the thread number of a thread in a team.
</li>
<li>
<b>OMP_GET_WTICK</b> returns the precision of the timer used by OMP_GET_WTIME.
</li>
<li>
<b>OMP_GET_WTIME</b> returns elapsed wall clock time in seconds.
</li>
<li>
<b>OMP_IN_PARALLEL</b> returns TRUE if the call is made from a parallel region.
</li>
<li>
<b>OMP_INIT_LOCK</b> initializes a simple lock.
</li>
<li>
<b>OMP_INIT_NEST_LOCK</b> initializes a nestable lock.
</li>
<li>
<b>OMP_SET_DYNAMIC</b> enables dynamic adjustment of the number of threads.
</li>
<li>
<b>OMP_SET_LOCK</b> sets a simple lock.
</li>
<li>
<b>OMP_SET_NEST_LOCK</b> sets a nestable lock.
</li>
<li>
<b>OMP_SET_NESTED</b> controls the use of nested parallelism.
</li>
<li>
<b>OMP_SET_NUM_THREADS</b> sets the number of threads.
</li>
<li>
<b>OMP_TEST_LOCK</b> tests a simple lock.
</li>
<li>
<b>OMP_TEST_NEST_LOCK</b> tests a nestable lock.
</li>
<li>
<b>OMP_UNSET_LOCK</b> unsets a simple lock.
</li>
<li>
<b>OMP_UNSET_NEST_LOCK</b> unsets a nestable lock.
</li>
</ul>
</p>
<p>
You can go up one level to <a href = "../cpp_src.html">
the C++ source codes</a>.
</p>
<hr>
<i>
Last revised on 20 November 2007.
</i>
<!-- John Burkardt -->
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