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12 <h1>Hash-Based Random-Integer <tt>find</tt> Find Timing
14 <h2><a name="description" id="description">Description</a></h2>
15 <p>This test inserts a number of values with uniform i.i.d.
16 integer keys into a container, then performs a series of finds
17 using <tt>find</tt>. It measures the average time
18 for<tt>find</tt> as a function of the number of values
20 <p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/random_int_find_timing.cc"><tt>random_int_find_timing_test</tt></a>
22 <h2><a name="purpose" id="purpose">Purpose</a></h2>
23 <p>The test checks the effect of different underlying
24 hash-tables (see <a href="hash_based_containers.html">Design::Associative
25 Containers::Associative Containers::Hash-Based Containers</a>),
26 range-hashing functions, and trigger policies (see <a href="hash_based_containers.html#hash_policies">Design::Associative
27 Containers::Hash-Based Containers::Hash Policies</a> and
28 <a href="hash_based_containers.html#resize_policies">Design::Associative
29 Containers::Hash-Based Containers::Resize Policies</a>).</p>
30 <h2><a name="results" id="results">Results</a></h2>
31 <p>Figures <a href="#NCCG">NCCG</a>, <a href="#NCCM">NCCM</a>,
32 and <a href="#NCCL">NCCL</a> show the results for the native
33 and 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
34 <a href="assoc_performance_tests.html#local"><u>local</u></a>,
35 respectively; Figures <a href="#NGPG">NGPG</a>, <a href="#NGPM">NGPM</a>, and <a href="#NGPL">NGPL</a> show the results
36 for the native and probing 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
37 <a href="assoc_performance_tests.html#local"><u>local</u></a>
39 <div id="NCCG_res_div">
41 <div id="NCCG_cc_hash_random_int_find_timing_test">
43 <div id="NCCG_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NCCG" id="NCCG"><img src="cc_hash_random_int_find_timing_test_gcc.png" alt="no image" /></a></h6>NCCG: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href="assoc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
47 <tt>std::tr1::unordered_map</tt> with <tt>cache_hash_code</tt> = <tt><b>false</b></tt></li>
49 cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_map-
50 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
51 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
52 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
53 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
54 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
55 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/1</i></li>
57 cc_hash_mod_prime_nea_lc_1div8_1div2_nsth_map-
58 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
59 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
60 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
61 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
62 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
63 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i></li>
65 cc_hash_mask_exp_nea_lc_1div8_1div1_nsth_map-
66 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
67 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
68 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
69 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
70 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
71 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/1</i></li>
73 cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_map-
74 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
75 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
76 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
77 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
78 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
79 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i></li>
81 </div><div style="width: 100%; height: 20px"></div></div>
86 <div id="NCCM_res_div">
88 <div id="NCCM_cc_hash_random_int_find_timing_test">
90 <div id="NCCM_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NCCM" id="NCCM"><img src="cc_hash_random_int_find_timing_test_msvc.png" alt="no image" /></a></h6>NCCM: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
93 cc_hash_mod_prime_nea_lc_1div8_1div1_nsth_map-
94 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
95 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
96 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
97 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
98 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
99 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/1</i></li>
101 cc_hash_mod_prime_nea_lc_1div8_1div2_nsth_map-
102 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
103 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
104 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
105 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
106 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
107 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i></li>
110 <tt>stdext::hash_map</tt></li>
112 cc_hash_mask_exp_nea_lc_1div8_1div1_nsth_map-
113 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
114 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
115 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
116 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
117 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
118 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/1</i></li>
120 cc_hash_mask_exp_nea_lc_1div8_1div2_nsth_map-
121 <a href="cc_hash_table.html"><tt>cc_hash_table</tt></a>
122 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
123 , and <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
124 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
125 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
126 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i></li>
128 </div><div style="width: 100%; height: 20px"></div></div>
133 <div id="NCCL_res_div">
134 <div id="NCCL_local">
135 <div id="NCCL_cc_hash_random_int_find_timing_test">
136 <div id="NCCL_assoc">
137 <div id="NCCL_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NCCL" id= "NCCL"><img src="cc_hash_random_int_find_timing_test_local.png" alt="no image" /></a></h6>NCCL: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
142 <div id="NGPG_res_div">
144 <div id="NGPG_gp_hash_random_int_find_timing_test">
145 <div id="NGPG_assoc">
146 <div id="NGPG_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NGPG" id="NGPG"><img src="gp_hash_random_int_find_timing_test_gcc.png" alt="no image" /></a></h6>NGPG: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href="assoc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the legends have the following meaning:</p>
149 gp_hash_mod_quadp_prime_nea_lc_1div8_1div2_nsth_map-
150 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
151 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
152 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
153 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
154 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
155 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="quadratic_probe_fn.html"><tt>quadratic_probe_fn</tt></a>
159 <tt>std::tr1::unordered_map</tt> with <tt>cache_hash_code</tt> = <tt><b>false</b></tt></li>
161 gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_map-
162 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
163 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
164 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
165 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
166 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
167 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<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>
170 </div><div style="width: 100%; height: 20px"></div></div>
175 <div id="NGPM_res_div">
177 <div id="NGPM_gp_hash_random_int_find_timing_test">
178 <div id="NGPM_assoc">
179 <div id="NGPM_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NGPM" id="NGPM"><img src="gp_hash_random_int_find_timing_test_msvc.png" alt="no image" /></a></h6>NGPM: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p>
182 gp_hash_mod_quadp_prime_nea_lc_1div8_1div2_nsth_map-
183 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
184 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mod_range_hashing.html"><tt>direct_mod_range_hashing</tt></a>
185 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
186 with <tt>Size_Policy</tt> = <a href="hash_prime_size_policy.html"><tt>hash_prime_size_policy</tt></a>
187 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
188 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<sub>max</sub></i> = <i>1/2</i>, and <tt>Probe_Fn</tt> = <a href="quadratic_probe_fn.html"><tt>quadratic_probe_fn</tt></a>
192 <tt>stdext::hash_map</tt></li>
194 gp_hash_mask_linp_exp_nea_lc_1div8_1div2_nsth_map-
195 <a href="gp_hash_table.html"><tt>gp_hash_table</tt></a>
196 with <tt>Comb_Hash_Fn</tt> = <a href="direct_mask_range_hashing.html"><tt>direct_mask_range_hashing</tt></a>
197 , <tt>Resize_Policy</tt> = <a href="hash_standard_resize_policy.html"><tt>hash_standard_resize_policy</tt></a>
198 with <tt>Size_Policy</tt> = <a href="hash_exponential_size_policy.html"><tt>hash_exponential_size_policy</tt></a>
199 , and <tt>Trigger_Policy</tt> = <a href="hash_load_check_resize_trigger.html"><tt>hash_load_check_resize_trigger</tt></a>
200 with <i>α<sub>min</sub></i> = <i>1/8</i> and <i>α<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>
203 </div><div style="width: 100%; height: 20px"></div></div>
208 <div id="NGPL_res_div">
209 <div id="NGPL_local">
210 <div id="NGPL_gp_hash_random_int_find_timing_test">
211 <div id="NGPL_assoc">
212 <div id="NGPL_Native_and_collision-chaining_hash_random_int_find_timing_test_using__tt_find_455tt_"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NGPL" id= "NGPL"><img src="gp_hash_random_int_find_timing_test_local.png" alt="no image" /></a></h6>NGPL: Native and collision-chaining hash random int find timing test using <tt>find</tt> - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
217 <h2><a name="observations" id="observations">Observations</a></h2>
218 <p>In this setting, the choice of underlying hash-table (see
219 <a href="hash_based_containers.html">Design::Associative
220 Containers::Hash-Based Containers</a> ) affects performance
221 most, then the range-hashing scheme (See <a href="hash_based_containers.html#hash_policies">Design::Associative
222 Containers::Hash-Based Containers::Hash Policies</a> ), and,
223 only finally, other policies.</p>
224 <p>When comparing Figures <a href="#NCCG">NCCG</a> and <a href="#NCCM">NCCM</a> to <a href="#NGPG">NGPG</a> and <a href="#NGPM">NGPM</a> , respectively, it is apparent that the
225 probing containers are less efficient than the
226 collision-chaining containers (both
227 <tt>std::tr1::unordered_map</tt> and <tt>stdext::hash_map</tt>
228 use collision-chaining) in this case.</p>
229 <p>( <a href="hash_random_int_subscript_insert_timing_test.html">Hash-Based
230 Random-Integer Subscript Insert Timing Test</a> shows a
231 different case, where the situation is reversed; <a href="assoc_performance_tests.html#hash_based_types">Observations::Hash-Based
232 Container Types</a> discusses some further considerations.)</p>
233 <p>Within each type of hash-table, the range-hashing scheme
234 affects performance more than other policies; <a href="hash_text_find_find_timing_test.html#observations">Hash-Based
235 Text <tt>find</tt> Find Timing Test::Observations</a> discusses
236 this. In Figures <a href="#NCCG">NCCG</a> , <a href="#NCCM">NCCM</a> , <a href="#NGPG">NGPG</a> , and <a href="#NGPM">NGPM</a> , it should be noted that
237 <tt>std::tr1::unordered_map</tt> and <tt>stdext::hash_map</tt>
238 are hard-wired currently to mod-based and mask-based schemes,
240 <p><a href="assoc_performance_tests.html#hash_based_types">Observations::Hash-Based
241 Container Types</a> summarizes some observations on hash-based
242 containers; <a href="assoc_performance_tests.html#hash_based_policies">Observations::Hash-Based
243 Containers' Policies</a> summarizes some observations on
244 hash-based containers' policies.</p>