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  1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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  2.     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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  3. 

  4. <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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  5. <head>
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  6. <meta name="generator" content="HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" />
    7. 

  7. <title>Tree Text Locality of Reference Timing Test</title>
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  8. <meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
    9. 

  9. </head>
    10. 

  10. <body>
    11. 

  11. <div id="page">
    12. 

  12. <h1>Hash-Based Erase Memory-Use Test</h1>
    13. 

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

  14. <p>This test inserts a number of uniform i.i.d. integer keys
    15. 

  15.     into a container, then erases all keys except one. It measures
    16. 

  16.     the final size of the container.</p>
    17. 

  17. <p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/hash_random_int_erase_mem_usage.cc"><tt>hash_random_int_erase_mem_usage.cc</tt></a>
    18. 

  18.     2000 2000 2100)</p>
    19. 

  19. <h2><a name="purpose" id="purpose">Purpose</a></h2>
    20. 

  20. <p>The test checks how containers adjust internally as their
    21. 

  21.     logical size decreases (see <a href="motivation.html#assoc_ers_methods">Motivation::Associative
    22. 

  22.     Containers::Slightly Different Methods::Methods Related to
    23. 

  23.     Erase</a>).</p>
    24. 

  24. <h2><a name="results" id="results">Results</a></h2>
    25. 

  25. <p>Figures <a href="#NHG">NHG</a>, <a href="#NHM">NHM</a> and
    26. 

  26.     <a href="#NHL">NHL</a> show the results for the native and
    27. 

  27.     collision-chaining types in <a href="assoc_performance_tests.html#gcc"><u>g++</u></a>, <a href="assoc_performance_tests.html#msvc"><u>msvc++</u></a> and
    28. 

  28.     <a href="assoc_performance_tests.html#local"><u>local</u></a>,
    29. 

  29.     respectively.</p>
    30. 

  30. <div id="NHG_res_div">
    31. 

  31. <div id="NHG_gcc">
    32. 

  32. <div id="NHG_hash_random_int_erase_mem_usage_test">
    33. 

  33. <div id="NHG_assoc">
    34. 

  34. <div id="NHG_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHG" id="NHG"><img src="hash_random_int_erase_mem_usage_test_gcc.png" alt="no image" /></a></h6>NHG: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
    35. 

  35. <ol>
    36. 

  36. <li>
    37. 

  37. n_hash_set_ncah-
    38. 

  38. <tt>std::tr1::unordered_set</tt> with <tt>cache_hash_code</tt> = <tt><b>false</b></tt></li>
    39. 

  39. <li>
    40. 

  40. gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
    41. 

  41. <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
    42. 

  42.  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    43. 

  43. , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    44. 

  44.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    45. 

  45. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    46. 

  46.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
    47. 

  47. </li>
    48. 

  48. <li>
    49. 

  49. cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
    50. 

  50. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    51. 

  51. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
    52. 

  52. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    53. 

  53.  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
    54. 

  54. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    55. 

  55.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
    56. 

  56. <li>
    57. 

  57. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
    58. 

  58. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    59. 

  59. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    60. 

  60. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    61. 

  61.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    62. 

  62. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    63. 

  63.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
    64. 

  64. </ol>
    65. 

  65. </div><div style="width: 100%; height: 20px"></div></div>
    66. 

  66. </div>
    67. 

  67. </div>
    68. 

  68. </div>
    69. 

  69. </div>
    70. 

  70. <div id="NHM_res_div">
    71. 

  71. <div id="NHM_msvc">
    72. 

  72. <div id="NHM_hash_random_int_erase_mem_usage_test">
    73. 

  73. <div id="NHM_assoc">
    74. 

  74. <div id="NHM_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHM" id="NHM"><img src="hash_random_int_erase_mem_usage_test_msvc.png" alt="no image" /></a></h6>NHM: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
    75. 

  75. <ol>
    76. 

  76. <li>
    77. 

  77. n_hash_set_ncah-
    78. 

  78. <tt>stdext::hash_set</tt></li>
    79. 

  79. <li>
    80. 

  80. gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
    81. 

  81. <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
    82. 

  82.  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    83. 

  83. , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    84. 

  84.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    85. 

  85. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    86. 

  86.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
    87. 

  87. </li>
    88. 

  88. <li>
    89. 

  89. cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
    90. 

  90. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    91. 

  91. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
    92. 

  92. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    93. 

  93.  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
    94. 

  94. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    95. 

  95.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
    96. 

  96. <li>
    97. 

  97. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
    98. 

  98. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    99. 

  99. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    100. 

  100. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    101. 

  101.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    102. 

  102. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    103. 

  103.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
    104. 

  104. </ol>
    105. 

  105. </div><div style="width: 100%; height: 20px"></div></div>
    106. 

  106. </div>
    107. 

  107. </div>
    108. 

  108. </div>
    109. 

  109. </div>
    110. 

  110. <div id="NHM_res_div">
    111. 

  111. <div id="NHM_msvc">
    112. 

  112. <div id="NHM_hash_random_int_erase_mem_usage_test">
    113. 

  113. <div id="NHM_assoc">
    114. 

  114. <div id="NHM_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHM" id="NHM"><img src="hash_random_int_erase_mem_usage_test_msvc.png" alt="no image" /></a></h6>NHM: Native, collision-chaing, and probing, hash random int erase test - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
    115. 

  115. <ol>
    116. 

  116. <li>
    117. 

  117. n_hash_set_ncah-
    118. 

  118. <tt>stdext::hash_set</tt></li>
    119. 

  119. <li>
    120. 

  120. gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_set-
    121. 

  121. <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
    122. 

  122.  with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    123. 

  123. , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    124. 

  124.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    125. 

  125. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    126. 

  126.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="linear_probe_fn.html"><tt>linear_probe_fn</tt></a>
    127. 

  127. </li>
    128. 

  128. <li>
    129. 

  129. cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_set-
    130. 

  130. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    131. 

  131. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
    132. 

  132. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    133. 

  133.  with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
    134. 

  134. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    135. 

  135.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/1</i></li>
    136. 

  136. <li>
    137. 

  137. cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_set-
    138. 

  138. <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
    139. 

  139. with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
    140. 

  140. , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
    141. 

  141.  with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
    142. 

  142. , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
    143. 

  143.  with <i>&alpha;<sub>min</sub></i> = <i>1/8</i> and <i>&alpha;<sub>max</sub></i> = <i>1/2</i></li>
    144. 

  144. </ol>
    145. 

  145. </div><div style="width: 100%; height: 20px"></div></div>
    146. 

  146. </div>
    147. 

  147. </div>
    148. 

  148. </div>
    149. 

  149. </div>
    150. 

  150. <div id="NHL_res_div">
    151. 

  151. <div id="NHL_local">
    152. 

  152. <div id="NHL_hash_random_int_erase_mem_usage_test">
    153. 

  153. <div id="NHL_assoc">
    154. 

  154. <div id="NHL_Native_456_collision-chaing_456_and_probing_456_hash_random_int_erase_test"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NHL" id= "NHL"><img src="hash_random_int_erase_mem_usage_test_local.png" alt="no image" /></a></h6>NHL: Native, collision-chaing, and probing, hash random int erase test - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
    155. 

  155. </div>
    156. 

  156. </div>
    157. 

  157. </div>
    158. 

  158. </div>
    159. 

  159. <h2><a name="observations" id="observations">Observations</a></h2>
    160. 

  160. <p>STL hash-based containers act very differently than trees in
    161. 

  161.     this respect. When erasing numerous keys from an STL
    162. 

  162.     associative-container, the resulting memory user varies greatly
    163. 

  163.     depending on whether the container is tree-based or hash-based.
    164. 

  164.     As noted in <a href="motivation.html#assoc_methods">Motivation::Choice of
    165. 

  165.     Methods</a> , this is a fundamental consequence of the STL's
    166. 

  166.     associative containers' interface, it is not due to a specific
    167. 

  167.     implementation.</p>
    168. 

  168. <p>(See <a href="priority_queue_text_pop_mem_usage_test.html">Priority Queue
    169. 

  169.     Text <tt>pop</tt> Memory Use Test</a> for a similar phenomenon
    170. 

  170.     regarding priority queues.)</p>
    171. 

  171. </div>
    172. 

  172. </body>
    173. 

  173. </html>
    174. 

  174.