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| 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), se
e www.w3.org" /> | |
| 7 <title>Tree Split Join 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 Split-Join Timing Test</h1> | |
| 13 <h2><a name="description" id="description">Description</a></h2> | |
| 14 <p>This test a container, inserts into a number of values, | |
| 15 splits the container at the median, and joins the two | |
| 16 containers. (If the containers are one of <tt>pb_ds</tt> 's | |
| 17 trees, it splits and joins with the <tt>split</tt> and | |
| 18 <tt>join</tt> method; otherwise, it uses the <tt>erase</tt> and | |
| 19 <tt>insert</tt> methods.) It measures the time for splitting | |
| 20 and joining the containers as a function of the number of | |
| 21 values inserted.</p> | |
| 22 <p>(The test was executed with <a href="http://gcc.gnu.org/viewcvs/*checkout*/tr
unk/libstdc%2B%2B-v3/testsuite/performance/ext/pb_ds/tree_split_join_timing.cc">
<tt>tree_split_join_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 <tt>join</tt> | |
| 26 as opposed to a sequence of <tt>insert</tt> operations; by | |
| 27 implication, this test checks the most efficient way to erase a | |
| 28 sub-sequence from a tree-like-based container, since this can | |
| 29 always be performed by a small sequence of splits and joins | |
| 30 (see <a href="motivation.html#assoc_split_join_methods">Motivation::Associat
ive | |
| 31 Containers::Slightly Different Methods::Methods Related to | |
| 32 Split and Join</a> and <a href="tree_based_containers.html#add_methods">Desi
gn::Associative | |
| 33 Containers::Tree-Based Containers::Additional Methods</a> | |
| 34 .)</p> | |
| 35 <h2><a name="results" id="results">Results</a></h2> | |
| 36 <p>Figures <a href="#NTG">NTG</a>, <a href="#NTM">NTM</a>, and | |
| 37 <a href="#NTL">NTL</a> show the results for the native and | |
| 38 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 | |
| 39 <a href="assoc_performance_tests.html#local"><u>local</u></a>, | |
| 40 respectively.</p> | |
| 41 <div id="NTG_res_div"> | |
| 42 <div id="NTG_gcc"> | |
| 43 <div id="NTG_tree_split_join_timing_test"> | |
| 44 <div id="NTG_assoc"> | |
| 45 <div id="NTG_Native_and_tree-based_container_splits_and_joins"><div style="borde
r-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a n
ame="NTG" id="NTG"><img src="tree_split_join_timing_test_gcc.png" alt="no image"
/></a></h6>NTG: Native and tree-based container splits and joins - <a href="ass
oc_performance_tests.html#gcc">g++</a><p>In the above figure, the names in the l
egends have the following meaning:</p> | |
| 46 <ol> | |
| 47 <li> | |
| 48 n_set- | |
| 49 <tt>std::set</tt></li> | |
| 50 <li> | |
| 51 splay_tree_set- | |
| 52 <a href="tree.html"><tt>tree</tt></a> | |
| 53 with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> | |
| 54 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 55 </li> | |
| 56 <li> | |
| 57 rb_tree_set- | |
| 58 <a href="tree.html"><tt>tree</tt></a> | |
| 59 with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> | |
| 60 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 61 </li> | |
| 62 <li> | |
| 63 ov_tree_set- | |
| 64 <a href="tree.html"><tt>tree</tt></a> | |
| 65 with <tt>Tag</tt> = <a href="ov_tree_tag.html"><tt>ov_tree_tag</tt></a> | |
| 66 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 67 </li> | |
| 68 </ol> | |
| 69 </div><div style="width: 100%; height: 20px"></div></div> | |
| 70 </div> | |
| 71 </div> | |
| 72 </div> | |
| 73 </div> | |
| 74 <div id="NTM_res_div"> | |
| 75 <div id="NTM_msvc"> | |
| 76 <div id="NTM_tree_split_join_timing_test"> | |
| 77 <div id="NTM_assoc"> | |
| 78 <div id="NTM_Native_and_tree-based_container_splits_and_joins"><div style="borde
r-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a n
ame="NTM" id="NTM"><img src="tree_split_join_timing_test_msvc.png" alt="no image
" /></a></h6>NTM: Native and tree-based container splits and joins - <a href="as
soc_performance_tests.html#msvc">msvc++</a><p>In the above figure, the names in
the legends have the following meaning:</p> | |
| 79 <ol> | |
| 80 <li> | |
| 81 n_set- | |
| 82 <tt>std::set</tt></li> | |
| 83 <li> | |
| 84 splay_tree_set- | |
| 85 <a href="tree.html"><tt>tree</tt></a> | |
| 86 with <tt>Tag</tt> = <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a> | |
| 87 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 88 </li> | |
| 89 <li> | |
| 90 rb_tree_set- | |
| 91 <a href="tree.html"><tt>tree</tt></a> | |
| 92 with <tt>Tag</tt> = <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> | |
| 93 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 94 </li> | |
| 95 <li> | |
| 96 ov_tree_set- | |
| 97 <a href="tree.html"><tt>tree</tt></a> | |
| 98 with <tt>Tag</tt> = <a href="ov_tree_tag.html"><tt>ov_tree_tag</tt></a> | |
| 99 , and <tt>Node_Update</tt> = <a href="null_tree_node_update.html"><tt>null_tree_
node_update</tt></a> | |
| 100 </li> | |
| 101 </ol> | |
| 102 </div><div style="width: 100%; height: 20px"></div></div> | |
| 103 </div> | |
| 104 </div> | |
| 105 </div> | |
| 106 </div> | |
| 107 <div id="NTL_res_div"> | |
| 108 <div id="NTL_local"> | |
| 109 <div id="NTL_tree_split_join_timing_test"> | |
| 110 <div id="NTL_assoc"> | |
| 111 <div id="NTL_Native_and_tree-based_container_splits_and_joins"><div style = "bor
der-style: dotted; border-width: 1px; border-color: lightgray"><h6 class="c1"><a
name="NTL" id= "NTL"><img src="tree_split_join_timing_test_local.png" alt="no i
mage" /></a></h6>NTL: Native and tree-based container splits and joins - <a href
= "assoc_performance_tests.html#local">local</a></div><div style = "width: 100%
; height: 20px"></div></div> | |
| 112 </div> | |
| 113 </div> | |
| 114 </div> | |
| 115 </div> | |
| 116 <h2><a name="observations" id="observations">Observations</a></h2> | |
| 117 <p>In this test, the native red-black trees must be split and | |
| 118 joined externally, through a sequence of <tt>erase</tt> and | |
| 119 <tt>insert</tt> operations. This is clearly super-linear, and | |
| 120 it is not that surprising that the cost is high.</p> | |
| 121 <p><tt>pb_ds</tt> 's tree-based containers use in this test the | |
| 122 <tt>split</tt> and <tt>join</tt> methods, which have lower | |
| 123 complexity: the <tt>join</tt> method of a splay tree ( <a href="tree.html"><
tt>tree</tt></a> | |
| 124 with <tt>Tag =</tt> <a href="splay_tree_tag.html"><tt>splay_tree_tag</tt></a
> ) is | |
| 125 quadratic in the length of the longest root-leaf path, and | |
| 126 linear in the total number of elements; the <tt>join</tt> | |
| 127 method of a red-black tree ( <a href="tree.html"><tt>tree</tt></a> | |
| 128 with <tt>Tag =</tt> <a href="rb_tree_tag.html"><tt>rb_tree_tag</tt></a> ) or
an | |
| 129 ordered-vector tree ( <a href="tree.html"><tt>tree</tt></a> | |
| 130 with <tt>Tag =</tt> <a href="ov_tree_tag.html"><tt>ov_tree_tag</tt></a> ) is
linear | |
| 131 in the number of elements.</p> | |
| 132 <p>Asides from orders of growth, <tt>pb_ds</tt> 's trees access | |
| 133 their allocator very little in these operations, and some of | |
| 134 them do not access it at all. This leads to lower constants in | |
| 135 their complexity, and, for some containers, to exception-free | |
| 136 splits and joins (which can be determined via <a href="assoc_container_trait
s.html"><tt>container_traits</tt></a>).</p> | |
| 137 <p>It is important to note that <tt>split</tt> and | |
| 138 <tt>join</tt> are not esoteric methods - they are the most | |
| 139 efficient means of erasing a contiguous range of values from a | |
| 140 tree based container.</p> | |
| 141 </div> | |
| 142 </body> | |
| 143 </html> | |
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Chromium Code Reviews
Issue 3050029:
[gcc] GCC 4.5.0=>4.5.1 (Closed)
Base URL: ssh://git@gitrw.chromium.org:9222/nacl-toolchain.git
