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  6. <meta name="generator" content="HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" />
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  7. <title>Priority Queue Text Modify (Down) Timing Test</title>
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  12. <h1>Priority Queue Text <tt>modify</tt> Timing Test - II</h1>
    13. 

  13. <h2><a name="description" id="description">Description</a></h2>
    14. 

  14. <p>This test inserts a number of values with keys from an
    15. 

  15.     arbitrary text ([ <a href="references.html#wickland96thirty">wickland96thirty</a> ]) into
    16. 

  16.     into a container then modifies each one "down" (<i>i.e.,</i> it
    17. 

  17.     makes it smaller). It uses <tt>modify</tt> for <tt>pb_ds</tt>'s
    18. 

  18.     priority queues; for the STL's priority queues, it pops values
    19. 

  19.     from a container until it reaches the value that should be
    20. 

  20.     modified, then pushes values back in. It measures the average
    21. 

  21.     time for <tt>modify</tt> as a function of the number of
    22. 

  22.     values.</p>
    23. 

  23. <p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/priority_queue_text_modify_timing.cc"><tt>priority_queue_text_modify_down_timing_test</tt></a>
    24. 

  24.     thirty_years_among_the_dead_preproc.txt 200 200 2100 f)</p>
    25. 

  25. <h2><a name="purpose" id="purpose">Purpose</a></h2>
    26. 

  26. <p>The main purpose of this test is to contrast <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
    27. 

  27.     Text <tt>modify</tt> Timing Test - I</a>.</p>
    28. 

  28. <h2><a name="results" id="results">Results</a></h2>
    29. 

  29. <p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and
    30. 

  30.     <a href="#NPL">NPL</a> show the results for the native priority
    31. 

  31.     queues and <tt>pb_ds</tt> 's priority queues in <a href="pq_performance_tests.html#gcc"><u>g++</u></a>, <a href="pq_performance_tests.html#msvc"><u>msvc++</u></a>, and
    32. 

  32.     <a href="pq_performance_tests.html#local"><u>local</u></a>,
    33. 

  33.     respectively; Figures <a href="#NRTG">NRTG</a>, <a href="#NRTM">NRTM</a>, and <a href="#NRTL">NRTL</a> show the results
    34. 

  34.     for the pairing heap and thin heaps in <a href="pq_performance_tests.html#gcc"><u>g++</u></a>, <a href="pq_performance_tests.html#msvc"><u>msvc++</u></a>, and
    35. 

  35.     <a href="pq_performance_tests.html#local"><u>local</u></a>,
    36. 

  36.     respectively,</p>
    37. 

  37. <div id="NPG_res_div">
    38. 

  38. <div id="NPG_gcc">
    39. 

  39. <div id="NPG_priority_queue_text_modify_down_timing_test">
    40. 

  40. <div id="NPG_pq">
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  41. <div id="NPG_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPG" id="NPG"><img src="priority_queue_text_modify_down_timing_test_gcc.png" alt="no image" /></a></h6>NPG: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
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  42. <ol>
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  43. <li>
    44. 

  44. n_pq_deque-
    45. 

  45. <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
    46. 

  46. <li>
    47. 

  47. n_pq_vector-
    48. 

  48. <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
    49. 

  49. <li>
    50. 

  50. binary_heap-
    51. 

  51. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    52. 

  52.  with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
    53. 

  53. </li>
    54. 

  54. <li>
    55. 

  55. thin_heap-
    56. 

  56. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    57. 

  57.  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
    58. 

  58. </li>
    59. 

  59. <li>
    60. 

  60. rc_binomial_heap-
    61. 

  61. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    62. 

  62.  with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
    63. 

  63. </li>
    64. 

  64. <li>
    65. 

  65. binomial_heap-
    66. 

  66. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    67. 

  67.  with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
    68. 

  68. </li>
    69. 

  69. <li>
    70. 

  70. pairing_heap-
    71. 

  71. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    72. 

  72.  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
    73. 

  73. </li>
    74. 

  74. </ol>
    75. 

  75. </div><div style="width: 100%; height: 20px"></div></div>
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  76. </div>
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  77. </div>
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  78. </div>
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  79. </div>
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  80. <div id="NPM_res_div">
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  81. <div id="NPM_msvc">
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  82. <div id="NPM_priority_queue_text_modify_down_timing_test">
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  83. <div id="NPM_pq">
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  84. <div id="NPM_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPM" id="NPM"><img src="priority_queue_text_modify_down_timing_test_msvc.png" alt="no image" /></a></h6>NPM: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
    85. 

  85. <ol>
    86. 

  86. <li>
    87. 

  87. n_pq_deque-
    88. 

  88. <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
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  89. <li>
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  90. n_pq_vector-
    91. 

  91. <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
    92. 

  92. <li>
    93. 

  93. binary_heap-
    94. 

  94. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    95. 

  95.  with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
    96. 

  96. </li>
    97. 

  97. <li>
    98. 

  98. thin_heap-
    99. 

  99. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    100. 

  100.  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
    101. 

  101. </li>
    102. 

  102. <li>
    103. 

  103. rc_binomial_heap-
    104. 

  104. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    105. 

  105.  with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
    106. 

  106. </li>
    107. 

  107. <li>
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  108. binomial_heap-
    109. 

  109. <a href="priority_queue.html"><tt>priority_queue</tt></a>
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  110.  with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
    111. 

  111. </li>
    112. 

  112. <li>
    113. 

  113. pairing_heap-
    114. 

  114. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    115. 

  115.  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
    116. 

  116. </li>
    117. 

  117. </ol>
    118. 

  118. </div><div style="width: 100%; height: 20px"></div></div>
    119. 

  119. </div>
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  120. </div>
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  121. </div>
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  122. </div>
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  123. <div id="NPL_res_div">
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  124. <div id="NPL_local">
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  125. <div id="NPL_priority_queue_text_modify_down_timing_test">
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  126. <div id="NPL_pq">
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  127. <div id="NPL_Native_and__tt_pb_ds_455tt__priority_queue__tt_modify_455tt__timing_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NPL" id= "NPL"><img src="priority_queue_text_modify_down_timing_test_local.png" alt="no image" /></a></h6>NPL: Native and <tt>pb ds</tt> priority queue <tt>modify</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
    128. 

  128. </div>
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  129. </div>
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  130. </div>
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  131. </div>
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  132. <div id="NRTG_res_div">
    133. 

  133. <div id="NRTG_gcc">
    134. 

  134. <div id="NRTG_priority_queue_text_modify_down_timing_test_pairing_thin">
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  135. <div id="NRTG_pq">
    136. 

  136. <div id="NRTG_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTG" id="NRTG"><img src="priority_queue_text_modify_down_timing_test_pairing_thin_gcc.png" alt="no image" /></a></h6>NRTG: Pairing and thin  priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
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  137. <ol>
    138. 

  138. <li>
    139. 

  139. thin_heap-
    140. 

  140. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    141. 

  141.  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
    142. 

  142. </li>
    143. 

  143. <li>
    144. 

  144. pairing_heap-
    145. 

  145. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    146. 

  146.  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
    147. 

  147. </li>
    148. 

  148. </ol>
    149. 

  149. </div><div style="width: 100%; height: 20px"></div></div>
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  150. </div>
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  151. </div>
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  152. </div>
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  153. </div>
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  154. <div id="NRTM_res_div">
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  155. <div id="NRTM_msvc">
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  156. <div id="NRTM_priority_queue_text_modify_down_timing_test_pairing_thin">
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  157. <div id="NRTM_pq">
    158. 

  158. <div id="NRTM_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTM" id="NRTM"><img src="priority_queue_text_modify_down_timing_test_pairing_thin_msvc.png" alt="no image" /></a></h6>NRTM: Pairing and thin  priority queue <tt>modify</tt> timing test - <a href="pq_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
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  159. <ol>
    160. 

  160. <li>
    161. 

  161. thin_heap-
    162. 

  162. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    163. 

  163.  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
    164. 

  164. </li>
    165. 

  165. <li>
    166. 

  166. pairing_heap-
    167. 

  167. <a href="priority_queue.html"><tt>priority_queue</tt></a>
    168. 

  168.  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
    169. 

  169. </li>
    170. 

  170. </ol>
    171. 

  171. </div><div style="width: 100%; height: 20px"></div></div>
    172. 

  172. </div>
    173. 

  173. </div>
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  174. </div>
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  175. </div>
    176. 

  176. <div id="NRTL_res_div">
    177. 

  177. <div id="NRTL_local">
    178. 

  178. <div id="NRTL_priority_queue_text_modify_down_timing_test_pairing_thin">
    179. 

  179. <div id="NRTL_pq">
    180. 

  180. <div id="NRTL_Pairing_and_thin__priority_queue__tt_modify_455tt__timing_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NRTL" id= "NRTL"><img src="priority_queue_text_modify_down_timing_test_pairing_thin_local.png" alt="no image" /></a></h6>NRTL: Pairing and thin  priority queue <tt>modify</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
    181. 

  181. </div>
    182. 

  182. </div>
    183. 

  183. </div>
    184. 

  184. </div>
    185. 

  185. <h2><a name="observations" id="observations">Observations</a></h2>
    186. 

  186. <p>Most points in these results are similar to <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
    187. 

  187.     Text <tt>modify</tt> Timing Test - I</a>.</p>
    188. 

  188. <p>It is interesting to note, however, that as opposed to that
    189. 

  189.     test, a thin heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
    190. 

  190.     <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>) is
    191. 

  191.     outperformed by a pairing heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
    192. 

  192.     <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>).
    193. 

  193.     In this case, both heaps essentially perform an <tt>erase</tt>
    194. 

  194.     operation followed by a <tt>push</tt> operation. As the other
    195. 

  195.     tests show, a pairing heap is usually far more efficient than a
    196. 

  196.     thin heap, so this is not surprising.</p>
    197. 

  197. <p>Most algorithms that involve priority queues increase values
    198. 

  198.     (in the sense of the priority queue's comparison functor), and
    199. 

  199.     so <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
    200. 

  200.     Text <tt>modify</tt> Timing Test - I</a> is more interesting
    201. 

  201.     than this test.</p>
    202. 

  202. </div>
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  203. </body>
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  204. </html>
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  205.