1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3 4<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 5<head> 6<meta name="generator" content="HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" /> 7<title>Tree Order Statistics Timing Test</title> 8<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" /> 9</head> 10<body> 11<div id="page"> 12<h1>Tree Order-Statistics Timing Test</h1> 13<h2><a name="description" id="description">Description</a></h2> 14<p>This test creates a container, inserts random integers into 15 the the container, and then checks the order-statistics of the 16 container's values. (If the container is one of <tt>pb_ds</tt> 17 's trees, it does this with the <tt>order_of_key</tt> method of 18 <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a> 19 ; otherwise, it uses the <tt>find</tt> method and 20 <tt>std::distance</tt> .) It measures the average time for such 21 queries as a function of the number of values inserted.</p> 22<p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/tree_order_statistics_timing.cc"><tt>tree_order_statistics_timing_test</tt></a> 23 200 200 2100)</p> 24<h2><a name="purpose" id="purpose">Purpose</a></h2> 25<p>The test checks the performance difference of policies based 26 on node-invariant as opposed to a external functions. (see 27 <a href="tree_based_containers.html#invariants">Design::Associative 28 Containers::Tree-Based Containers::Node Invariants</a> .)</p> 29<h2><a name="results" id="results">Results</a></h2> 30<p>Figures <a href="#NTG">NTG</a>, <a href="#NTM">NTM</a>, and 31 <a href="#NTL">NTL</a> show the results for the native and 32 tree-based containers in <a href="assoc_performance_tests.html#gcc"><u>g++</u></a>, <a href="assoc_performance_tests.html#msvc"><u>msvc++</u></a>, and 33 <a href="assoc_performance_tests.html#local"><u>local</u></a>, 34 respectively.</p> 35<div id="NTG_res_div"> 36<div id="NTG_gcc"> 37<div id="NTG_tree_order_statistics_timing_test"> 38<div id="NTG_assoc"> 39<div id="NTG_Native_and_tree-based_container_order-statistics_queries"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTG" id="NTG"><img src="tree_order_statistics_timing_test_gcc.png" alt="no image" /></a></h6>NTG: Native and tree-based container order-statistics queries - <a href="assoc_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> 42n_set- 43<tt>std::set</tt></li> 44<li> 45splay_tree_ost_set- 46<a href="tree.html"><tt>tree</tt></a> 47 with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> 48, and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a> 49</li> 50<li> 51rb_tree_ost_set- 52<a href="tree.html"><tt>tree</tt></a> 53 with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> 54, and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a> 55</li> 56</ol> 57</div><div style="width: 100%; height: 20px"></div></div> 58</div> 59</div> 60</div> 61</div> 62<div id="NTM_res_div"> 63<div id="NTM_msvc"> 64<div id="NTM_tree_order_statistics_timing_test"> 65<div id="NTM_assoc"> 66<div id="NTM_Native_and_tree-based_container_order-statistics_queries"><div style="border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTM" id="NTM"><img src="tree_order_statistics_timing_test_msvc.png" alt="no image" /></a></h6>NTM: Native and tree-based container order-statistics queries - <a href="assoc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in the legends have the following meaning:</p> 67<ol> 68<li> 69n_set- 70<tt>std::set</tt></li> 71<li> 72splay_tree_ost_set- 73<a href="tree.html"><tt>tree</tt></a> 74 with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> 75, and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a> 76</li> 77<li> 78rb_tree_ost_set- 79<a href="tree.html"><tt>tree</tt></a> 80 with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> 81, and <tt>Node_Update</tt> = <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a> 82</li> 83</ol> 84</div><div style="width: 100%; height: 20px"></div></div> 85</div> 86</div> 87</div> 88</div> 89<div id="NTL_res_div"> 90<div id="NTL_local"> 91<div id="NTL_tree_order_statistics_timing_test"> 92<div id="NTL_assoc"> 93<div id="NTL_Native_and_tree-based_container_order-statistics_queries"><div style = "border-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a name="NTL" id= "NTL"><img src="tree_order_statistics_timing_test_local.png" alt="no image" /></a></h6>NTL: Native and tree-based container order-statistics queries - <a href = "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%; height: 20px"></div></div> 94</div> 95</div> 96</div> 97</div> 98<h2><a name="observations" id="observations">Observations</a></h2> 99<p>In this test, the native red-black tree can support 100 order-statistics queries only externally, by performing a 101 <tt>find</tt> (alternatively, <tt>lower_bound</tt> or 102 <tt>upper_bound</tt> ) and then using <tt>std::distance</tt> . 103 This is clearly linear, and it is not that surprising that the 104 cost is high.</p> 105<p><tt>pb_ds</tt> 's tree-based containers use in this test the 106 <tt>order_of_key</tt> method of <a href="tree_order_statistics_node_update.html"><tt>tree_order_statistics_node_update</tt></a>. 107 This method has only linear complexity in the length of the 108 root-node path. Unfortunately, the average path of a splay tree 109 (<a href="tree.html"><tt>tree</tt></a> 110 with <tt>Tag =</tt> <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> ) can 111 be higher than logarithmic; the longest path of a red-black 112 tree (<a href="tree.html"><tt>tree</tt></a> 113 with <tt>Tag =</tt> <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> ) is 114 logarithmic in the number of elements. Consequently, the splay 115 tree has worse performance than the red-black tree.</p> 116</div> 117</body> 118</html> 119