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comparison: src/share/vm/gc_implementation/shared/gcOverheadReporter.hpp

src/share/vm/gc_implementation/shared/gcOverheadReporter.hpp

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1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Keeps track of the GC overhead (both concurrent and STW). It stores
26 // it in a large array and then prints it to tty at the end of the
27 // execution.
28
29 // See coTracker.hpp for the explanation on what groups are.
30
31 // Let's set a maximum number of concurrent overhead groups, to
32 // statically allocate any arrays we need and not to have to
33 // malloc/free them. This is just a bit more convenient.
34 enum {
35 MaxGCOverheadGroupNum = 4
36 };
37
38 typedef struct {
39 double _start_sec;
40 double _end_sec;
41
42 double _conc_overhead[MaxGCOverheadGroupNum];
43 double _stw_overhead;
44 } GCOverheadReporterEntry;
45
46 class GCOverheadReporter {
47 friend class COReportingThread;
48
49 private:
50 enum PrivateConstants {
51 DefaultReporterLength = 128 * 1024
52 };
53
54 // Reference to the single instance of this class.
55 static GCOverheadReporter* _reporter;
56
57 // These three references point to the array that contains the GC
58 // overhead entries (_base is the base of the array, _top is the
59 // address passed the last entry of the array, _curr is the next
60 // entry to be used).
61 GCOverheadReporterEntry* _base;
62 GCOverheadReporterEntry* _top;
63 GCOverheadReporterEntry* _curr;
64
65 // The number of concurrent overhead groups.
66 size_t _group_num;
67
68 // The wall-clock time of the end of the last recorded period of GC
69 // overhead.
70 double _prev_end_sec;
71
72 // Names for the concurrent overhead groups.
73 const char* _group_names[MaxGCOverheadGroupNum];
74
75 // Add a new entry to the large array. conc_overhead being NULL is
76 // equivalent to an array full of 0.0s. conc_overhead should have a
77 // length of at least _group_num.
78 void add(double start_sec, double end_sec,
79 double* conc_overhead,
80 double stw_overhead);
81
82 // Add an entry that represents concurrent GC overhead.
83 // conc_overhead must be at least of length _group_num.
84 // conc_overhead being NULL is equivalent to an array full of 0.0s.
85 void add_conc_overhead(double start_sec, double end_sec,
86 double* conc_overhead) {
87 add(start_sec, end_sec, conc_overhead, 0.0);
88 }
89
90 // Add an entry that represents STW GC overhead.
91 void add_stw_overhead(double start_sec, double end_sec,
92 double stw_overhead) {
93 add(start_sec, end_sec, NULL, stw_overhead);
94 }
95
96 // It records the start of a STW pause (i.e. it records the
97 // concurrent overhead up to that point)
98 void record_stw_start(double start_sec);
99
100 // It records the end of a STW pause (i.e. it records the overhead
101 // associated with the pause and adjusts all the trackers to reflect
102 // the pause)
103 void record_stw_end(double end_sec);
104
105 // It queries all the trackers of their concurrent overhead and
106 // records it.
107 void collect_and_record_conc_overhead(double end_sec);
108
109 // It prints the contents of the GC overhead array
110 void print() const;
111
112
113 // Constructor. The same preconditions for group_num and group_names
114 // from initGCOverheadReporter apply here too.
115 GCOverheadReporter(size_t group_num,
116 const char* group_names[],
117 size_t length = DefaultReporterLength);
118
119 public:
120
121 // statics
122
123 // It initialises the GCOverheadReporter and launches the concurrent
124 // overhead reporting thread. Both actions happen only if the
125 // GCOverheadReporting parameter is set. The length of the
126 // group_names array should be >= group_num and group_num should be
127 // <= MaxGCOverheadGroupNum. Entries group_namnes[0..group_num-1]
128 // should not be NULL.
129 static void initGCOverheadReporter(size_t group_num,
130 const char* group_names[]);
131
132 // The following three are provided for convenience and they are
133 // wrappers around record_stw_start(start_sec), record_stw_end(end_sec),
134 // and print(). Each of these checks whether GC overhead reporting
135 // is on (i.e. _reporter != NULL) and, if it is, calls the
136 // corresponding method. Saves from repeating this pattern again and
137 // again from the places where they need to be called.
138 static void recordSTWStart(double start_sec);
139 static void recordSTWEnd(double end_sec);
140 static void printGCOverhead();
141 };

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