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Re: [PATCH][libstdc++-v3 parallel mode] PR 33491

Benjamin Kosnik wrote:

> Just add the individual papers cited:
> To the bottom of parallel_mode.html in a new section at the bottom of
> the page called "References/Further Reading."

Done and committed as attached.

2007-10-08  Johannes Singler  <>

      * docs/html/parallel_mode.html: Added reference to MCSTL.
      More documentation on compile-time settings and tuning.
      * include/parallel/multiway_merge.h: Added reference to paper.
      * include/parallel/multiseq_selection.h: Added reference to paper.
      * include/parallel/workstealing.h: Added reference to paper.
      * include/parallel/balanced_quicksort.h: Added reference to paper.
      * include/parallel/tree.h: Added reference to paper.

Index: docs/html/parallel_mode.html
--- docs/html/parallel_mode.html	(revision 129126)
+++ docs/html/parallel_mode.html	(working copy)
@@ -35,7 +35,7 @@
 Several of the standard algorithms, for instance
-<code>std::search</code>, are made parallel using OpenMP
+<code>std::sort</code>, are made parallel using OpenMP
 annotations. These parallel mode constructs and can be invoked by
 explicit source declaration or by compiling existing sources with a
 specific compiler flag.
@@ -43,7 +43,7 @@
 <h3 class="left"><a name="parallel">The libstdc++ parallel mode</a></h3>
-<p>The libstdc++ parallel mode performs parallization of algorithms,
+<p>The libstdc++ parallel mode performs parallelization of algorithms,
 function objects, classes, and functions in the C++ Standard.</p>
 <h4 class="left">Using the libstdc++ parallel mode</h4>
@@ -53,7 +53,7 @@
   will link in <code>libgomp</code>, the GNU OpenMP <a
   whose presence is mandatory. In addition, hardware capable of atomic
-  operations is de rigueur. Actually activating these atomic
+  operations is mandatory. Actually activating these atomic
   operations may require explicit compiler flags on some targets
   (like sparc and x86), such as <code>-march=i686</code>,
   <code>-march=native</code> or <code>-mcpu=v9</code>.
@@ -113,7 +113,14 @@
+<p>The following library components in the includes
+<code>&lt;set&gt;</code> and <code>&lt;map&gt;</code> are included in the parallel mode:</p>
+  <li><code>std::(multi_)map/set&lt;T&gt;::(multi_)map/set(Iterator begin, Iterator end)</code> (bulk construction)</li>
+  <li><code>std::(multi_)map/set&lt;T&gt;::insert(Iterator begin, Iterator end)</code> (bulk insertion)</li>
 <h4 class="left">Using the parallel algorithms without parallel mode</h4>
 <p>When it is not feasible to recompile your entire application, or
@@ -380,14 +387,48 @@
 <h4 class="left">Parallel mode semantics</h4>
-<p> Something about exception safety, interaction with threads,
-etc. Goal is to have the usual constraints of the STL with respect to
-exception safety and threads, but add in support for parallel
-<p> Something about compile-time settings and configuration, ie using
-<code>__gnu_parallel::Settings</code>. XXX Up in the air.</p>
+<p> The parallel mode STL algorithms are currently not exception-safe,
+i. e. user-defined functors must not throw exceptions.
+<p> Since the current GCC OpenMP implementation does not support
+OpenMP parallel regions in concurrent threads,
+it is not possible to call parallel STL algorithm in
+concurrent threads, either.
+It might work with other compilers, though.</p>
+<h4 class="left">Configuration and Tuning</h4>
+<p> Some algorithm variants can be enabled/disabled/selected at compile-time.
+See <a href="latest-doxygen/compiletime__settings_8h.html">
+<code>&lt;compiletime_settings.h&gt;</code></a> and
+See <a href="latest-doxygen/compiletime__settings_8h.html">
+<code>&lt;features.h&gt;</code></a> for details.
+To specify the number of threads to be used for an algorithm,
+use <code>omp_set_num_threads</code>.
+To force a function to execute sequentially,
+even though parallelism is switched on in general,
+add <code>__gnu_parallel::sequential_tag()</code>
+to the end of the argument list.
+Parallelism always incurs some overhead. Thus, it is not
+helpful to parallelize operations on very small sets of data.
+There are measures to avoid parallelizing stuff that is not worth it.
+For each algorithm, a minimum problem size can be stated,
+usually using the variable
+Please see <a href="latest-doxygen/settings_8h.html">
+<code>&lt;settings.h&gt;</code><a> for details.</p>
 <h4 class="left">Interface basics and general design</h4>
 <p>All parallel algorithms are intended to have signatures that are
@@ -485,7 +526,7 @@
 &lt;algorithm&gt; has a parallel counterpart in
 <code>std::__parallel::transform</code> from
 &lt;parallel/algorithm&gt;. In addition, these parallel
-implementatations are injected into <code>namespace
+implementations are injected into <code>namespace
 __gnu_parallel</code> with using declarations.
@@ -526,6 +567,16 @@
+<h4 class="left">References / Further Reading</h4>
+Johannes Singler, Peter Sanders, Felix Putze. The Multi-Core Standard Template Library. Euro-Par 2007: Parallel Processing. (LNCS 4641)
+Leonor Frias, Johannes Singler: Parallelization of Bulk Operations for STL Dictionaries. Workshop on Highly Parallel Processing on a Chip (HPPC) 2007. (LNCS)
 <!-- ####################################################### -->
 <hr />
Index: include/parallel/multiway_merge.h
--- include/parallel/multiway_merge.h	(revision 129126)
+++ include/parallel/multiway_merge.h	(working copy)
@@ -30,6 +30,13 @@
 /** @file parallel/multiway_merge.h
  *  @brief Implementation of sequential and parallel multiway merge.
+ *
+ *  Explanations on the high-speed merging routines in the appendix of
+ *
+ *  P. Sanders.
+ *  Fast priority queues for cached memory.
+ *  ACM Journal of Experimental Algorithmics, 5, 2000.
+ *
  *  This file is a GNU parallel extension to the Standard C++ Library.
Index: include/parallel/multiseq_selection.h
--- include/parallel/multiseq_selection.h	(revision 129126)
+++ include/parallel/multiseq_selection.h	(working copy)
@@ -32,6 +32,13 @@
  *  @brief Functions to find elements of a certain global rank in
  *  multiple sorted sequences.  Also serves for splitting such
  *  sequence sets.
+ *
+ *  The algorithm description can be found in 
+ *
+ *  P. J. Varman, S. D. Scheufler, B. R. Iyer, and G. R. Ricard.
+ *  Merging Multiple Lists on Hierarchical-Memory Multiprocessors.
+ *  Journal of Parallel and Distributed Computing, 12(2):171â??177, 1991.
+ *
  *  This file is a GNU parallel extension to the Standard C++ Library.
Index: include/parallel/workstealing.h
--- include/parallel/workstealing.h	(revision 129126)
+++ include/parallel/workstealing.h	(working copy)
@@ -31,6 +31,13 @@
 /** @file parallel/workstealing.h
  *  @brief Parallelization of embarrassingly parallel execution by
  *  means of work-stealing.
+ *
+ *  Work stealing is described in
+ *
+ *  R. D. Blumofe and C. E. Leiserson.
+ *  Scheduling multithreaded computations by work stealing.
+ *  Journal of the ACM, 46(5):720â??748, 1999.
+ *
  *  This file is a GNU parallel extension to the Standard C++ Library.
Index: include/parallel/balanced_quicksort.h
--- include/parallel/balanced_quicksort.h	(revision 129126)
+++ include/parallel/balanced_quicksort.h	(working copy)
@@ -32,6 +32,14 @@
  *  @brief Implementation of a dynamically load-balanced parallel quicksort.
  *  It works in-place and needs only logarithmic extra memory.
+ *  The algorithm is similar to the one proposed in
+ *
+ *  P. Tsigas and Y. Zhang.
+ *  A simple, fast parallel implementation of quicksort and
+ *  its performance evaluation on SUN enterprise 10000.
+ *  In 11th Euromicro Conference on Parallel, Distributed and
+ *  Network-Based Processing, page 372, 2003.
+ *
  *  This file is a GNU parallel extension to the Standard C++ Library.
Index: include/parallel/tree.h
--- include/parallel/tree.h	(revision 129126)
+++ include/parallel/tree.h	(working copy)
@@ -30,6 +30,13 @@
 /** @file parallel/tree.h
  *  @brief Parallel red-black tree operations.
+ *
+ *  This implementation is described in
+ *
+ *  Leonor Frias, Johannes Singler.
+ *  Parallelization of Bulk Operations for STL Dictionaries.
+ *  Workshop on Highly Parallel Processing on a Chip (HPPC) 2007.
+ *
  *  This file is a GNU parallel extension to the Standard C++ Library.

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