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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Design</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><meta name="keywords" content=" C++ , library , parallel " /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="parallel_mode.html" title="Chapter 31. Parallel Mode" /><link rel="prev" href="bk01pt12ch31s03.html" title="Using" /><link rel="next" href="bk01pt12ch31s05.html" title="Testing" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Design</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bk01pt12ch31s03.html">Prev</a> </td><th width="60%" align="center">Chapter 31. Parallel Mode</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt12ch31s05.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="Design"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.ext.parallel_mode.design"></a>Design</h2></div></div></div><p>
|
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Design</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><meta name="keywords" content=" C++ , library , parallel " /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="parallel_mode.html" title="Chapter 31. Parallel Mode" /><link rel="prev" href="bk01pt12ch31s03.html" title="Using" /><link rel="next" href="bk01pt12ch31s05.html" title="Testing" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Design</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bk01pt12ch31s03.html">Prev</a> </td><th width="60%" align="center">Chapter 31. Parallel Mode</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt12ch31s05.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="Design"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.ext.parallel_mode.design"></a>Design</h2></div></div></div><p>
|
</p><div class="sect2" title="Interface Basics"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.intro"></a>Interface Basics</h3></div></div></div><p>
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</p><div class="sect2" title="Interface Basics"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.intro"></a>Interface Basics</h3></div></div></div><p>
|
All parallel algorithms are intended to have signatures that are
|
All parallel algorithms are intended to have signatures that are
|
equivalent to the ISO C++ algorithms replaced. For instance, the
|
equivalent to the ISO C++ algorithms replaced. For instance, the
|
<code class="function">std::adjacent_find</code> function is declared as:
|
<code class="function">std::adjacent_find</code> function is declared as:
|
</p><pre class="programlisting">
|
</p><pre class="programlisting">
|
namespace std
|
namespace std
|
{
|
{
|
template<typename _FIter>
|
template<typename _FIter>
|
_FIter
|
_FIter
|
adjacent_find(_FIter, _FIter);
|
adjacent_find(_FIter, _FIter);
|
}
|
}
|
</pre><p>
|
</pre><p>
|
Which means that there should be something equivalent for the parallel
|
Which means that there should be something equivalent for the parallel
|
version. Indeed, this is the case:
|
version. Indeed, this is the case:
|
</p><pre class="programlisting">
|
</p><pre class="programlisting">
|
namespace std
|
namespace std
|
{
|
{
|
namespace __parallel
|
namespace __parallel
|
{
|
{
|
template<typename _FIter>
|
template<typename _FIter>
|
_FIter
|
_FIter
|
adjacent_find(_FIter, _FIter);
|
adjacent_find(_FIter, _FIter);
|
|
|
...
|
...
|
}
|
}
|
}
|
}
|
</pre><p>But.... why the ellipses?
|
</pre><p>But.... why the ellipses?
|
</p><p> The ellipses in the example above represent additional overloads
|
</p><p> The ellipses in the example above represent additional overloads
|
required for the parallel version of the function. These additional
|
required for the parallel version of the function. These additional
|
overloads are used to dispatch calls from the ISO C++ function
|
overloads are used to dispatch calls from the ISO C++ function
|
signature to the appropriate parallel function (or sequential
|
signature to the appropriate parallel function (or sequential
|
function, if no parallel functions are deemed worthy), based on either
|
function, if no parallel functions are deemed worthy), based on either
|
compile-time or run-time conditions.
|
compile-time or run-time conditions.
|
</p><p> The available signature options are specific for the different
|
</p><p> The available signature options are specific for the different
|
algorithms/algorithm classes.</p><p> The general view of overloads for the parallel algorithms look like this:
|
algorithms/algorithm classes.</p><p> The general view of overloads for the parallel algorithms look like this:
|
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>ISO C++ signature</p></li><li class="listitem"><p>ISO C++ signature + sequential_tag argument</p></li><li class="listitem"><p>ISO C++ signature + algorithm-specific tag type
|
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>ISO C++ signature</p></li><li class="listitem"><p>ISO C++ signature + sequential_tag argument</p></li><li class="listitem"><p>ISO C++ signature + algorithm-specific tag type
|
(several signatures)</p></li></ul></div><p> Please note that the implementation may use additional functions
|
(several signatures)</p></li></ul></div><p> Please note that the implementation may use additional functions
|
(designated with the <code class="code">_switch</code> suffix) to dispatch from the
|
(designated with the <code class="code">_switch</code> suffix) to dispatch from the
|
ISO C++ signature to the correct parallel version. Also, some of the
|
ISO C++ signature to the correct parallel version. Also, some of the
|
algorithms do not have support for run-time conditions, so the last
|
algorithms do not have support for run-time conditions, so the last
|
overload is therefore missing.
|
overload is therefore missing.
|
</p></div><div class="sect2" title="Configuration and Tuning"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.tuning"></a>Configuration and Tuning</h3></div></div></div><div class="sect3" title="Setting up the OpenMP Environment"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.omp"></a>Setting up the OpenMP Environment</h4></div></div></div><p>
|
</p></div><div class="sect2" title="Configuration and Tuning"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.tuning"></a>Configuration and Tuning</h3></div></div></div><div class="sect3" title="Setting up the OpenMP Environment"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.omp"></a>Setting up the OpenMP Environment</h4></div></div></div><p>
|
Several aspects of the overall runtime environment can be manipulated
|
Several aspects of the overall runtime environment can be manipulated
|
by standard OpenMP function calls.
|
by standard OpenMP function calls.
|
</p><p>
|
</p><p>
|
To specify the number of threads to be used for the algorithms globally,
|
To specify the number of threads to be used for the algorithms globally,
|
use the function <code class="function">omp_set_num_threads</code>. An example:
|
use the function <code class="function">omp_set_num_threads</code>. An example:
|
</p><pre class="programlisting">
|
</p><pre class="programlisting">
|
#include <stdlib.h>
|
#include <stdlib.h>
|
#include <omp.h>
|
#include <omp.h>
|
|
|
int main()
|
int main()
|
{
|
{
|
// Explicitly set number of threads.
|
// Explicitly set number of threads.
|
const int threads_wanted = 20;
|
const int threads_wanted = 20;
|
omp_set_dynamic(false);
|
omp_set_dynamic(false);
|
omp_set_num_threads(threads_wanted);
|
omp_set_num_threads(threads_wanted);
|
|
|
// Call parallel mode algorithms.
|
// Call parallel mode algorithms.
|
|
|
return 0;
|
return 0;
|
}
|
}
|
</pre><p>
|
</pre><p>
|
Some algorithms allow the number of threads being set for a particular call,
|
Some algorithms allow the number of threads being set for a particular call,
|
by augmenting the algorithm variant.
|
by augmenting the algorithm variant.
|
See the next section for further information.
|
See the next section for further information.
|
</p><p>
|
</p><p>
|
Other parts of the runtime environment able to be manipulated include
|
Other parts of the runtime environment able to be manipulated include
|
nested parallelism (<code class="function">omp_set_nested</code>), schedule kind
|
nested parallelism (<code class="function">omp_set_nested</code>), schedule kind
|
(<code class="function">omp_set_schedule</code>), and others. See the OpenMP
|
(<code class="function">omp_set_schedule</code>), and others. See the OpenMP
|
documentation for more information.
|
documentation for more information.
|
</p></div><div class="sect3" title="Compile Time Switches"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.compile"></a>Compile Time Switches</h4></div></div></div><p>
|
</p></div><div class="sect3" title="Compile Time Switches"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.compile"></a>Compile Time Switches</h4></div></div></div><p>
|
To force an algorithm to execute sequentially, even though parallelism
|
To force an algorithm to execute sequentially, even though parallelism
|
is switched on in general via the macro <code class="constant">_GLIBCXX_PARALLEL</code>,
|
is switched on in general via the macro <code class="constant">_GLIBCXX_PARALLEL</code>,
|
add <code class="classname">__gnu_parallel::sequential_tag()</code> to the end
|
add <code class="classname">__gnu_parallel::sequential_tag()</code> to the end
|
of the algorithm's argument list.
|
of the algorithm's argument list.
|
</p><p>
|
</p><p>
|
Like so:
|
Like so:
|
</p><pre class="programlisting">
|
</p><pre class="programlisting">
|
std::sort(v.begin(), v.end(), __gnu_parallel::sequential_tag());
|
std::sort(v.begin(), v.end(), __gnu_parallel::sequential_tag());
|
</pre><p>
|
</pre><p>
|
Some parallel algorithm variants can be excluded from compilation by
|
Some parallel algorithm variants can be excluded from compilation by
|
preprocessor defines. See the doxygen documentation on
|
preprocessor defines. See the doxygen documentation on
|
<code class="code">compiletime_settings.h</code> and <code class="code">features.h</code> for details.
|
<code class="code">compiletime_settings.h</code> and <code class="code">features.h</code> for details.
|
</p><p>
|
</p><p>
|
For some algorithms, the desired variant can be chosen at compile-time by
|
For some algorithms, the desired variant can be chosen at compile-time by
|
appending a tag object. The available options are specific to the particular
|
appending a tag object. The available options are specific to the particular
|
algorithm (class).
|
algorithm (class).
|
</p><p>
|
</p><p>
|
For the "embarrassingly parallel" algorithms, there is only one "tag object
|
For the "embarrassingly parallel" algorithms, there is only one "tag object
|
type", the enum _Parallelism.
|
type", the enum _Parallelism.
|
It takes one of the following values,
|
It takes one of the following values,
|
<code class="code">__gnu_parallel::parallel_tag</code>,
|
<code class="code">__gnu_parallel::parallel_tag</code>,
|
<code class="code">__gnu_parallel::balanced_tag</code>,
|
<code class="code">__gnu_parallel::balanced_tag</code>,
|
<code class="code">__gnu_parallel::unbalanced_tag</code>,
|
<code class="code">__gnu_parallel::unbalanced_tag</code>,
|
<code class="code">__gnu_parallel::omp_loop_tag</code>,
|
<code class="code">__gnu_parallel::omp_loop_tag</code>,
|
<code class="code">__gnu_parallel::omp_loop_static_tag</code>.
|
<code class="code">__gnu_parallel::omp_loop_static_tag</code>.
|
This means that the actual parallelization strategy is chosen at run-time.
|
This means that the actual parallelization strategy is chosen at run-time.
|
(Choosing the variants at compile-time will come soon.)
|
(Choosing the variants at compile-time will come soon.)
|
</p><p>
|
</p><p>
|
For the following algorithms in general, we have
|
For the following algorithms in general, we have
|
<code class="code">__gnu_parallel::parallel_tag</code> and
|
<code class="code">__gnu_parallel::parallel_tag</code> and
|
<code class="code">__gnu_parallel::default_parallel_tag</code>, in addition to
|
<code class="code">__gnu_parallel::default_parallel_tag</code>, in addition to
|
<code class="code">__gnu_parallel::sequential_tag</code>.
|
<code class="code">__gnu_parallel::sequential_tag</code>.
|
<code class="code">__gnu_parallel::default_parallel_tag</code> chooses the default
|
<code class="code">__gnu_parallel::default_parallel_tag</code> chooses the default
|
algorithm at compiletime, as does omitting the tag.
|
algorithm at compiletime, as does omitting the tag.
|
<code class="code">__gnu_parallel::parallel_tag</code> postpones the decision to runtime
|
<code class="code">__gnu_parallel::parallel_tag</code> postpones the decision to runtime
|
(see next section).
|
(see next section).
|
For all tags, the number of threads desired for this call can optionally be
|
For all tags, the number of threads desired for this call can optionally be
|
passed to the respective tag's constructor.
|
passed to the respective tag's constructor.
|
</p><p>
|
</p><p>
|
The <code class="code">multiway_merge</code> algorithm comes with the additional choices,
|
The <code class="code">multiway_merge</code> algorithm comes with the additional choices,
|
<code class="code">__gnu_parallel::exact_tag</code> and
|
<code class="code">__gnu_parallel::exact_tag</code> and
|
<code class="code">__gnu_parallel::sampling_tag</code>.
|
<code class="code">__gnu_parallel::sampling_tag</code>.
|
Exact and sampling are the two available splitting strategies.
|
Exact and sampling are the two available splitting strategies.
|
</p><p>
|
</p><p>
|
For the <code class="code">sort</code> and <code class="code">stable_sort</code> algorithms, there are
|
For the <code class="code">sort</code> and <code class="code">stable_sort</code> algorithms, there are
|
several additional choices, namely
|
several additional choices, namely
|
<code class="code">__gnu_parallel::multiway_mergesort_tag</code>,
|
<code class="code">__gnu_parallel::multiway_mergesort_tag</code>,
|
<code class="code">__gnu_parallel::multiway_mergesort_exact_tag</code>,
|
<code class="code">__gnu_parallel::multiway_mergesort_exact_tag</code>,
|
<code class="code">__gnu_parallel::multiway_mergesort_sampling_tag</code>,
|
<code class="code">__gnu_parallel::multiway_mergesort_sampling_tag</code>,
|
<code class="code">__gnu_parallel::quicksort_tag</code>, and
|
<code class="code">__gnu_parallel::quicksort_tag</code>, and
|
<code class="code">__gnu_parallel::balanced_quicksort_tag</code>.
|
<code class="code">__gnu_parallel::balanced_quicksort_tag</code>.
|
Multiway mergesort comes with the two splitting strategies for multi-way
|
Multiway mergesort comes with the two splitting strategies for multi-way
|
merging. The quicksort options cannot be used for <code class="code">stable_sort</code>.
|
merging. The quicksort options cannot be used for <code class="code">stable_sort</code>.
|
</p></div><div class="sect3" title="Run Time Settings and Defaults"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.settings"></a>Run Time Settings and Defaults</h4></div></div></div><p>
|
</p></div><div class="sect3" title="Run Time Settings and Defaults"><div class="titlepage"><div><div><h4 class="title"><a id="parallel_mode.design.tuning.settings"></a>Run Time Settings and Defaults</h4></div></div></div><p>
|
The default parallelization strategy, the choice of specific algorithm
|
The default parallelization strategy, the choice of specific algorithm
|
strategy, the minimum threshold limits for individual parallel
|
strategy, the minimum threshold limits for individual parallel
|
algorithms, and aspects of the underlying hardware can be specified as
|
algorithms, and aspects of the underlying hardware can be specified as
|
desired via manipulation
|
desired via manipulation
|
of <code class="classname">__gnu_parallel::_Settings</code> member data.
|
of <code class="classname">__gnu_parallel::_Settings</code> member data.
|
</p><p>
|
</p><p>
|
First off, the choice of parallelization strategy: serial, parallel,
|
First off, the choice of parallelization strategy: serial, parallel,
|
or heuristically deduced. This corresponds
|
or heuristically deduced. This corresponds
|
to <code class="code">__gnu_parallel::_Settings::algorithm_strategy</code> and is a
|
to <code class="code">__gnu_parallel::_Settings::algorithm_strategy</code> and is a
|
value of enum <span class="type">__gnu_parallel::_AlgorithmStrategy</span>
|
value of enum <span class="type">__gnu_parallel::_AlgorithmStrategy</span>
|
type. Choices
|
type. Choices
|
include: <span class="type">heuristic</span>, <span class="type">force_sequential</span>,
|
include: <span class="type">heuristic</span>, <span class="type">force_sequential</span>,
|
and <span class="type">force_parallel</span>. The default is <span class="type">heuristic</span>.
|
and <span class="type">force_parallel</span>. The default is <span class="type">heuristic</span>.
|
</p><p>
|
</p><p>
|
Next, the sub-choices for algorithm variant, if not fixed at compile-time.
|
Next, the sub-choices for algorithm variant, if not fixed at compile-time.
|
Specific algorithms like <code class="function">find</code> or <code class="function">sort</code>
|
Specific algorithms like <code class="function">find</code> or <code class="function">sort</code>
|
can be implemented in multiple ways: when this is the case,
|
can be implemented in multiple ways: when this is the case,
|
a <code class="classname">__gnu_parallel::_Settings</code> member exists to
|
a <code class="classname">__gnu_parallel::_Settings</code> member exists to
|
pick the default strategy. For
|
pick the default strategy. For
|
example, <code class="code">__gnu_parallel::_Settings::sort_algorithm</code> can
|
example, <code class="code">__gnu_parallel::_Settings::sort_algorithm</code> can
|
have any values of
|
have any values of
|
enum <span class="type">__gnu_parallel::_SortAlgorithm</span>: <span class="type">MWMS</span>, <span class="type">QS</span>,
|
enum <span class="type">__gnu_parallel::_SortAlgorithm</span>: <span class="type">MWMS</span>, <span class="type">QS</span>,
|
or <span class="type">QS_BALANCED</span>.
|
or <span class="type">QS_BALANCED</span>.
|
</p><p>
|
</p><p>
|
Likewise for setting the minimal threshold for algorithm
|
Likewise for setting the minimal threshold for algorithm
|
parallelization. Parallelism always incurs some overhead. Thus, it is
|
parallelization. Parallelism always incurs some overhead. Thus, it is
|
not helpful to parallelize operations on very small sets of
|
not helpful to parallelize operations on very small sets of
|
data. Because of this, measures are taken to avoid parallelizing below
|
data. Because of this, measures are taken to avoid parallelizing below
|
a certain, pre-determined threshold. For each algorithm, a minimum
|
a certain, pre-determined threshold. For each algorithm, a minimum
|
problem size is encoded as a variable in the
|
problem size is encoded as a variable in the
|
active <code class="classname">__gnu_parallel::_Settings</code> object. This
|
active <code class="classname">__gnu_parallel::_Settings</code> object. This
|
threshold variable follows the following naming scheme:
|
threshold variable follows the following naming scheme:
|
<code class="code">__gnu_parallel::_Settings::[algorithm]_minimal_n</code>. So,
|
<code class="code">__gnu_parallel::_Settings::[algorithm]_minimal_n</code>. So,
|
for <code class="function">fill</code>, the threshold variable
|
for <code class="function">fill</code>, the threshold variable
|
is <code class="code">__gnu_parallel::_Settings::fill_minimal_n</code>,
|
is <code class="code">__gnu_parallel::_Settings::fill_minimal_n</code>,
|
</p><p>
|
</p><p>
|
Finally, hardware details like L1/L2 cache size can be hardwired
|
Finally, hardware details like L1/L2 cache size can be hardwired
|
via <code class="code">__gnu_parallel::_Settings::L1_cache_size</code> and friends.
|
via <code class="code">__gnu_parallel::_Settings::L1_cache_size</code> and friends.
|
</p><p>
|
</p><p>
|
</p><p>
|
</p><p>
|
All these configuration variables can be changed by the user, if
|
All these configuration variables can be changed by the user, if
|
desired.
|
desired.
|
There exists one global instance of the class <code class="classname">_Settings</code>,
|
There exists one global instance of the class <code class="classname">_Settings</code>,
|
i. e. it is a singleton. It can be read and written by calling
|
i. e. it is a singleton. It can be read and written by calling
|
<code class="code">__gnu_parallel::_Settings::get</code> and
|
<code class="code">__gnu_parallel::_Settings::get</code> and
|
<code class="code">__gnu_parallel::_Settings::set</code>, respectively.
|
<code class="code">__gnu_parallel::_Settings::set</code>, respectively.
|
Please note that the first call return a const object, so direct manipulation
|
Please note that the first call return a const object, so direct manipulation
|
is forbidden.
|
is forbidden.
|
See <a class="ulink" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01005.html" target="_top">
|
See <a class="ulink" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01005.html" target="_top">
|
<code class="filename">settings.h</code></a>
|
<code class="filename">settings.h</code></a>
|
for complete details.
|
for complete details.
|
</p><p>
|
</p><p>
|
A small example of tuning the default:
|
A small example of tuning the default:
|
</p><pre class="programlisting">
|
</p><pre class="programlisting">
|
#include <parallel/algorithm>
|
#include <parallel/algorithm>
|
#include <parallel/settings.h>
|
#include <parallel/settings.h>
|
|
|
int main()
|
int main()
|
{
|
{
|
__gnu_parallel::_Settings s;
|
__gnu_parallel::_Settings s;
|
s.algorithm_strategy = __gnu_parallel::force_parallel;
|
s.algorithm_strategy = __gnu_parallel::force_parallel;
|
__gnu_parallel::_Settings::set(s);
|
__gnu_parallel::_Settings::set(s);
|
|
|
// Do work... all algorithms will be parallelized, always.
|
// Do work... all algorithms will be parallelized, always.
|
|
|
return 0;
|
return 0;
|
}
|
}
|
</pre></div></div><div class="sect2" title="Implementation Namespaces"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.impl"></a>Implementation Namespaces</h3></div></div></div><p> One namespace contain versions of code that are always
|
</pre></div></div><div class="sect2" title="Implementation Namespaces"><div class="titlepage"><div><div><h3 class="title"><a id="parallel_mode.design.impl"></a>Implementation Namespaces</h3></div></div></div><p> One namespace contain versions of code that are always
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explicitly sequential:
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explicitly sequential:
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<code class="code">__gnu_serial</code>.
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<code class="code">__gnu_serial</code>.
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</p><p> Two namespaces contain the parallel mode:
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</p><p> Two namespaces contain the parallel mode:
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<code class="code">std::__parallel</code> and <code class="code">__gnu_parallel</code>.
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<code class="code">std::__parallel</code> and <code class="code">__gnu_parallel</code>.
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</p><p> Parallel implementations of standard components, including
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</p><p> Parallel implementations of standard components, including
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template helpers to select parallelism, are defined in <code class="code">namespace
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template helpers to select parallelism, are defined in <code class="code">namespace
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std::__parallel</code>. For instance, <code class="function">std::transform</code> from <code class="filename">algorithm</code> has a parallel counterpart in
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std::__parallel</code>. For instance, <code class="function">std::transform</code> from <code class="filename">algorithm</code> has a parallel counterpart in
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<code class="function">std::__parallel::transform</code> from <code class="filename">parallel/algorithm</code>. In addition, these parallel
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<code class="function">std::__parallel::transform</code> from <code class="filename">parallel/algorithm</code>. In addition, these parallel
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implementations are injected into <code class="code">namespace
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implementations are injected into <code class="code">namespace
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__gnu_parallel</code> with using declarations.
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__gnu_parallel</code> with using declarations.
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</p><p> Support and general infrastructure is in <code class="code">namespace
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</p><p> Support and general infrastructure is in <code class="code">namespace
|
__gnu_parallel</code>.
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__gnu_parallel</code>.
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</p><p> More information, and an organized index of types and functions
|
</p><p> More information, and an organized index of types and functions
|
related to the parallel mode on a per-namespace basis, can be found in
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related to the parallel mode on a per-namespace basis, can be found in
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the generated source documentation.
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the generated source documentation.
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