libstdc++-v3/doc/html/ext/pb_ds/priority_queue_random_int_push_pop_timing_test.html

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   7 <title>Priority Queue Random Int Push Pop Timing Test</title>
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  12 <h1>Priority Queue Random Integer <tt>push</tt> and
  13     <tt>pop</tt> Timing Test</h1>
  14 <h2><a name="description" id="description">Description</a></h2>
  15 <p>This test inserts a number of values with i.i.d. integer
  16     keys into a container using <tt>push</tt> , then removes them
  17     using <tt>pop</tt> . It measures the average time for
  18     <tt>push</tt> and <tt>pop</tt> as a function of the number of
  19     values.</p>
  20 <p>(The test was executed with <a href="../../../../testsuite/performance/ext/pb_ds/priority_queue_random_int_push_pop_timing.cc">
  21 <tt>priority_queue_random_int_push_pop_timing_test</tt></a>
  22     thirty_years_among_the_dead_preproc.txt 200 200 2100)</p>
  23 <h2><a name="purpose" id="purpose">Purpose</a></h2>
  24 <p>The test checks the effect of different underlying
  25     data structures (see <a href="pq_design.html#pq_imp">Design::Priority
  26     Queues::Implementations</a>).</p>
  27 <h2><a name="results" id="results">Results</a></h2>
  28 <p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and
  29     <a href="#NPL">NPL</a> shows the results for the native
  30     priority queues and <tt>pb_ds</tt> 's priority queues in
  31     <a href="pq_performance_tests.html#gcc"><u>g++</u></a>,
  32     <a href="pq_performance_tests.html#msvc"><u>msvc++</u></a>, and
  33     <a href="pq_performance_tests.html#local"><u>local</u></a>,
  34     respectively.</p>
  35 <div id="NPG_res_div">
  36 <div id="NPG_gcc">
  37 <div id="NPG_priority_queue_random_int_push_pop_timing_test">
  38 <div id="NPG_pq">
  39 <div id="NPG_Native_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt___tt_pop_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_random_int_push_pop_timing_test_gcc.png" alt="no image" /></a></h6>NPG: Native and <tt>pb ds</tt> priority queue <tt>push</tt> <tt>pop</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>
  40 <ol>
  41 <li>
  42 thin_heap-
  43 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  44  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
  45 </li>
  46 <li>
  47 rc_binomial_heap-
  48 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  49  with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
  50 </li>
  51 <li>
  52 binomial_heap-
  53 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  54  with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
  55 </li>
  56 <li>
  57 pairing_heap-
  58 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  59  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
  60 </li>
  61 <li>
  62 n_pq_deque-
  63 <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
  64 <li>
  65 n_pq_vector-
  66 <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
  67 <li>
  68 binary_heap-
  69 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  70  with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
  71 </li>
  72 </ol>
  73 </div><div style="width: 100%; height: 20px"></div></div>
  74 </div>
  75 </div>
  76 </div>
  77 </div>
  78 <div id="NPM_res_div">
  79 <div id="NPM_msvc">
  80 <div id="NPM_priority_queue_random_int_push_pop_timing_test">
  81 <div id="NPM_pq">
  82 <div id="NPM_Native_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt___tt_pop_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_random_int_push_pop_timing_test_msvc.png" alt="no image" /></a></h6>NPM: Native and <tt>pb ds</tt> priority queue <tt>push</tt> <tt>pop</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>
  83 <ol>
  84 <li>
  85 thin_heap-
  86 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  87  with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
  88 </li>
  89 <li>
  90 rc_binomial_heap-
  91 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  92  with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
  93 </li>
  94 <li>
  95 binomial_heap-
  96 <a href="priority_queue.html"><tt>priority_queue</tt></a>
  97  with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
  98 </li>
  99 <li>
 100 pairing_heap-
 101 <a href="priority_queue.html"><tt>priority_queue</tt></a>
 102  with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
 103 </li>
 104 <li>
 105 n_pq_deque-
 106 <tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
 107 <li>
 108 n_pq_vector-
 109 <tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
 110 <li>
 111 binary_heap-
 112 <a href="priority_queue.html"><tt>priority_queue</tt></a>
 113  with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
 114 </li>
 115 </ol>
 116 </div><div style="width: 100%; height: 20px"></div></div>
 117 </div>
 118 </div>
 119 </div>
 120 </div>
 121 <div id="NPL_res_div">
 122 <div id="NPL_local">
 123 <div id="NPL_priority_queue_random_int_push_pop_timing_test">
 124 <div id="NPL_pq">
 125 <div id="NPL_Native_and__tt_pb_ds_455tt__priority_queue__tt_push_455tt___tt_pop_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_random_int_push_pop_timing_test_local.png" alt="no image" /></a></h6>NPL: Native and <tt>pb ds</tt> priority queue <tt>push</tt> <tt>pop</tt> timing test - <a href = "pq_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div>
 126 </div>
 127 </div>
 128 </div>
 129 </div>
 130 <h2><a name="observations" id="observations">Observations</a></h2>
 131 <p>Binary heaps are the most suited for sequences of
 132     <tt>push</tt> and <tt>pop</tt> operations of primitive types
 133     (<i>e.g.</i> <tt><b>int</b></tt>s). This is explained in
 134     <a href="priority_queue_random_int_push_timing_test.html">Priority
 135     Queue Random Int <tt>push</tt> Timing Test</a> . (See <a href="priority_queue_text_push_pop_timing_test.html">Priority Queue
 136     Text <tt>push</tt> Timing Test</a> for the case of primitive
 137     types.)</p>
 138 <p>At first glance it seems that the STL's vector-based
 139     priority queue is approximately on par with <tt>pb_ds</tt>'s
 140     corresponding priority queue. There are two differences
 141     however:</p>
 142 <ol>
 143 <li>The STL's priority queue does not downsize the underlying
 144       vector (or deque) as the priority queue becomes smaller
 145       (see <a href="priority_queue_text_pop_mem_usage_test.html">Priority Queue
 146       Text <tt>pop</tt> Memory Use Test</a>). It is therefore
 147       gaining some speed at the expense of space.</li>
 148 <li>From <a href="priority_queue_random_int_push_pop_timing_test.html">Priority
 149       Queue Random Integer <tt>push</tt> and <tt>pop</tt> Timing
 150       Test</a>, it seems that the STL's priority queue is slower in
 151       terms of <tt>pus</tt> operations. Since the number of
 152       <tt>pop</tt> operations is at most that of <tt>push</tt>
 153       operations, the test here is the "best" for the STL's
 154       priority queue.</li>
 155 </ol>
 156 <p><a href="pq_performance_tests.html#pq_observations">Priority-Queue
 157     Performance Tests::Observations</a> discusses this further and
 158     summarizes.</p>
 159 </div>
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