1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta name="generator" content="HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" />
<title>Priority Queue Text Modify (Up) Timing Test</title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
</head>
<body>
<div id="page">
<h1>Priority Queue Text <tt>modify</tt> Timing Test - I</h1>
<h2><a name="description" id="description">Description</a></h2>
<p>This test inserts a number of values with keys from an
arbitrary text ([ <a href="references.html#wickland96thirty">wickland96thirty</a> ]) into
into a container then modifies each one "up" (<i>i.e.,</i> it
makes it larger). It uses <tt>modify</tt> for <tt>pb_ds</tt>'s
priority queues; for the STL's priority queues, it pops values
from a container until it reaches the value that should be
modified, then pushes values back in. It measures the average
time for <tt>modify</tt> as a function of the number of
values.</p>
<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_up_timing_test</tt></a>
thirty_years_among_the_dead_preproc.txt 200 200 2100 t)</p>
<h2><a name="purpose" id="purpose">Purpose</a></h2>
<p>The test checks the effect of different underlying
data structures (see <a href="pq_design.html#pq_imp">Design::Priority
Queues::Implementations</a>) for graph algorithms settings.
Note that making an arbitrary value larger (in the sense of the
priority queue's comparison functor) corresponds to
decrease-key in standard graph algorithms [<a href="references.html#clrs2001">clrs2001</a>].</p>
<h2><a name="results" id="results">Results</a></h2>
<p>Figures <a href="#NPG">NPG</a>, <a href="#NPM">NPM</a>, and
<a href="#NPL">NPL</a> show the results for the native priority
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
<a href="pq_performance_tests.html#local"><u>local</u></a>,
respectively; Figures <a href="#NRTG">NRTG</a>, <a href="#NRTM">NRTM</a>, and <a href="#NRTL">NRTL</a> show the results
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
<a href="pq_performance_tests.html#local"><u>local</u></a>,
respectively,</p>
<div id="NPG_res_div">
<div id="NPG_gcc">
<div id="NPG_priority_queue_text_modify_up_timing_test">
<div id="NPG_pq">
<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_up_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>
<ol>
<li>
n_pq_deque-
<tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
<li>
n_pq_vector-
<tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
<li>
binary_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
</li>
<li>
rc_binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
</li>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NPM_res_div">
<div id="NPM_msvc">
<div id="NPM_priority_queue_text_modify_up_timing_test">
<div id="NPM_pq">
<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_up_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>
<ol>
<li>
n_pq_deque-
<tt>std::priority_queue</tt> adapting <tt>std::deque</tt></li>
<li>
n_pq_vector-
<tt>std::priority_queue</tt> adapting <tt>std::vector</tt></li>
<li>
binary_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binary_heap_tag.html"><tt>binary_heap_tag</tt></a>
</li>
<li>
rc_binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="rc_binomial_heap_tag.html"><tt>rc_binomial_heap_tag</tt></a>
</li>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
binomial_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="binomial_heap_tag.html"><tt>binomial_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NPL_res_div">
<div id="NPL_local">
<div id="NPL_priority_queue_text_modify_up_timing_test">
<div id="NPL_pq">
<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_up_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>
</div>
</div>
</div>
</div>
<div id="NRTG_res_div">
<div id="NRTG_gcc">
<div id="NRTG_priority_queue_text_modify_up_timing_test_pairing_thin">
<div id="NRTG_pq">
<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_up_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>
<ol>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NRTM_res_div">
<div id="NRTM_msvc">
<div id="NRTM_priority_queue_text_modify_up_timing_test_pairing_thin">
<div id="NRTM_pq">
<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_up_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>
<ol>
<li>
pairing_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>
</li>
<li>
thin_heap-
<a href="priority_queue.html"><tt>priority_queue</tt></a>
with <tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>
</li>
</ol>
</div><div style="width: 100%; height: 20px"></div></div>
</div>
</div>
</div>
</div>
<div id="NRTL_res_div">
<div id="NRTL_local">
<div id="NRTL_priority_queue_text_modify_up_timing_test_pairing_thin">
<div id="NRTL_pq">
<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_up_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>
</div>
</div>
</div>
</div>
<h2><a name="observations" id="observations">Observations</a></h2>
<p>As noted above, increasing an arbitrary value (in the sense
of the priority queue's comparison functor) is very common in
graph-related algorithms. In this case, a thin heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
<tt>Tag</tt> = <a href="thin_heap_tag.html"><tt>thin_heap_tag</tt></a>)
outperforms a pairing heap (<a href="priority_queue.html"><tt>priority_queue</tt></a> with
<tt>Tag</tt> = <a href="pairing_heap_tag.html"><tt>pairing_heap_tag</tt></a>).
Conversely, <a href="priority_queue_text_push_timing_test.html">Priority Queue Text
<tt>push</tt> Timing Test</a>, <a href="priority_queue_text_push_pop_timing_test.html">Priority Queue
Text <tt>push</tt> and <tt>pop</tt> Timing Test</a>, <a href="priority_queue_random_int_push_timing_test.html">Priority
Queue Random Integer <tt>push</tt> Timing Test</a>, and
<a href="priority_queue_random_int_push_pop_timing_test.html">Priority
Queue Random Integer <tt>push</tt> and <tt>pop</tt> Timing
Test</a> show that the situation is reversed for other
operations. It is not clear when to prefer one of these two
different types.</p>
<p>In this test <tt>pb_ds</tt>'s binary heaps effectively
perform modify in linear time. As explained in <a href="pq_design.html#pq_traits">Priority Queue Design::Traits</a>,
given a valid point-type iterator, a binary heap can perform
<tt>modify</tt> logarithmically. The problem is that binary
heaps invalidate their find iterators with each modifying
operation, and so the only way to obtain a valid point-type
iterator is to iterate using a range-type iterator until
finding the appropriate value, then use the range-type iterator
for the <tt>modify</tt> operation.</p>
<p>The explanation for the STL's priority queues' performance
is similar to that in <a href="priority_queue_text_join_timing_test.html">Priority Queue Text
<tt>join</tt> Timing Test</a>.</p>
<p><a href="pq_performance_tests.html#pq_observations">Priority-Queue
Performance Tests::Observations</a> discusses this further and
summarizes.</p>
</div>
</body>
</html>
|
