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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 <h2><a name="description" id="description">Description</a></h2>
14 <p>This test inserts a number of values with keys from an
15 arbitrary text ([ <a href="references.html#wickland96thirty">wickland96thirty</a> ]) into
16 into a container then modifies each one "down" (<i>i.e.,</i> it
17 makes it smaller). It uses <tt>modify</tt> for <tt>pb_ds</tt>'s
18 priority queues; for the STL's priority queues, it pops values
19 from a container until it reaches the value that should be
20 modified, then pushes values back in. It measures the average
21 time for <tt>modify</tt> as a function of the number of
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 thirty_years_among_the_dead_preproc.txt 200 200 2100 f)</p>
25 <h2><a name="purpose" id="purpose">Purpose</a></h2>
26 <p>The main purpose of this test is to contrast <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
27 Text <tt>modify</tt> Timing Test - I</a>.</p>
28 <h2><a name="results" id="results">Results</a></h2>
29 <p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and
30 <a href="#NPL">NPL</a> show the results for the native priority
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 <a href="pq_performance_tests.html#local"><u>local</u></a>,
33 respectively; Figures <a href="#NRTG">NRTG</a>, <a href="#NRTM">NRTM</a>, and <a href="#NRTL">NRTL</a> show the results
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 <a href="pq_performance_tests.html#local"><u>local</u></a>,
37 <div id="NPG_res_div">
39 <div id="NPG_priority_queue_text_modify_down_timing_test">
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>
45 <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
48 <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
51 <a href="priority_queue.html"><tt>priority_queue</tt></a>
52 with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
56 <a href="priority_queue.html"><tt>priority_queue</tt></a>
57 with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
61 <a href="priority_queue.html"><tt>priority_queue</tt></a>
62 with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
66 <a href="priority_queue.html"><tt>priority_queue</tt></a>
67 with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
71 <a href="priority_queue.html"><tt>priority_queue</tt></a>
72 with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
75 </div><div style="width: 100%; height: 20px"></div></div>
80 <div id="NPM_res_div">
82 <div id="NPM_priority_queue_text_modify_down_timing_test">
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>
88 <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
91 <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
94 <a href="priority_queue.html"><tt>priority_queue</tt></a>
95 with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
99 <a href="priority_queue.html"><tt>priority_queue</tt></a>
100 with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
104 <a href="priority_queue.html"><tt>priority_queue</tt></a>
105 with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
109 <a href="priority_queue.html"><tt>priority_queue</tt></a>
110 with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
114 <a href="priority_queue.html"><tt>priority_queue</tt></a>
115 with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
118 </div><div style="width: 100%; height: 20px"></div></div>
123 <div id="NPL_res_div">
125 <div id="NPL_priority_queue_text_modify_down_timing_test">
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>
132 <div id="NRTG_res_div">
134 <div id="NRTG_priority_queue_text_modify_down_timing_test_pairing_thin">
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>
140 <a href="priority_queue.html"><tt>priority_queue</tt></a>
141 with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
145 <a href="priority_queue.html"><tt>priority_queue</tt></a>
146 with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
149 </div><div style="width: 100%; height: 20px"></div></div>
154 <div id="NRTM_res_div">
156 <div id="NRTM_priority_queue_text_modify_down_timing_test_pairing_thin">
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>
162 <a href="priority_queue.html"><tt>priority_queue</tt></a>
163 with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
167 <a href="priority_queue.html"><tt>priority_queue</tt></a>
168 with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
171 </div><div style="width: 100%; height: 20px"></div></div>
176 <div id="NRTL_res_div">
177 <div id="NRTL_local">
178 <div id="NRTL_priority_queue_text_modify_down_timing_test_pairing_thin">
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>
185 <h2><a name="observations" id="observations">Observations</a></h2>
186 <p>Most points in these results are similar to <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
187 Text <tt>modify</tt> Timing Test - I</a>.</p>
188 <p>It is interesting to note, however, that as opposed to that
189 test, a thin heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
190 <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>) is
191 outperformed by a pairing heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
192 <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>).
193 In this case, both heaps essentially perform an <tt>erase</tt>
194 operation followed by a <tt>push</tt> operation. As the other
195 tests show, a pairing heap is usually far more efficient than a
196 thin heap, so this is not surprising.</p>
197 <p>Most algorithms that involve priority queues increase values
198 (in the sense of the priority queue's comparison functor), and
199 so <a href="priority_queue_text_modify_up_timing_test.html">Priority Queue
200 Text <tt>modify</tt> Timing Test - I</a> is more interesting