1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP
27
28 #ifndef SERIALGC
29 #include "gc_implementation/shared/gcUtil.hpp"
30 #include "memory/allocation.hpp"
31 #include "utilities/globalDefinitions.hpp"
32 #endif
33
34 class AllocationStats VALUE_OBJ_CLASS_SPEC {
35 // A duration threshold (in ms) used to filter
36 // possibly unreliable samples.
37 static float _threshold;
38
39 // We measure the demand between the end of the previous sweep and
40 // beginning of this sweep:
41 // Count(end_last_sweep) - Count(start_this_sweep)
42 // + splitBirths(between) - splitDeaths(between)
43 // The above number divided by the time since the end of the
44 // previous sweep gives us a time rate of demand for blocks
45 // of this size. We compute a padded average of this rate as
46 // our current estimate for the time rate of demand for blocks
47 // of this size. Similarly, we keep a padded average for the time
48 // between sweeps. Our current estimate for demand for blocks of
49 // this size is then simply computed as the product of these two
50 // estimates.
51 AdaptivePaddedAverage _demand_rate_estimate;
52
53 ssize_t _desired; // Demand stimate computed as described above
54 ssize_t _coalDesired; // desired +/- small-percent for tuning coalescing
55
56 ssize_t _surplus; // count - (desired +/- small-percent),
57 // used to tune splitting in best fit
58 ssize_t _bfrSurp; // surplus at start of current sweep
59 ssize_t _prevSweep; // count from end of previous sweep
60 ssize_t _beforeSweep; // count from before current sweep
61 ssize_t _coalBirths; // additional chunks from coalescing
62 ssize_t _coalDeaths; // loss from coalescing
63 ssize_t _splitBirths; // additional chunks from splitting
64 ssize_t _splitDeaths; // loss from splitting
65 size_t _returnedBytes; // number of bytes returned to list.
66 public:
67 void initialize(bool split_birth = false) {
68 AdaptivePaddedAverage* dummy =
69 new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight,
70 CMS_FLSPadding);
71 _desired = 0;
72 _coalDesired = 0;
73 _surplus = 0;
74 _bfrSurp = 0;
75 _prevSweep = 0;
76 _beforeSweep = 0;
77 _coalBirths = 0;
78 _coalDeaths = 0;
79 _splitBirths = split_birth? 1 : 0;
80 _splitDeaths = 0;
81 _returnedBytes = 0;
82 }
83
84 AllocationStats() {
85 initialize();
86 }
87
88 // The rate estimate is in blocks per second.
89 void compute_desired(size_t count,
90 float inter_sweep_current,
91 float inter_sweep_estimate,
92 float intra_sweep_estimate) {
93 // If the latest inter-sweep time is below our granularity
94 // of measurement, we may call in here with
95 // inter_sweep_current == 0. However, even for suitably small
96 // but non-zero inter-sweep durations, we may not trust the accuracy
97 // of accumulated data, since it has not been "integrated"
98 // (read "low-pass-filtered") long enough, and would be
99 // vulnerable to noisy glitches. In such cases, we
100 // ignore the current sample and use currently available
101 // historical estimates.
102 // XXX NEEDS TO BE FIXED
103 // assert(prevSweep() + splitBirths() >= splitDeaths() + (ssize_t)count, "Conservation Principle");
104 // ^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
105 // "Total Stock" "Not used at this block size"
106 if (inter_sweep_current > _threshold) {
107 ssize_t demand = prevSweep() - (ssize_t)count + splitBirths() - splitDeaths();
108 // XXX NEEDS TO BE FIXED
109 // assert(demand >= 0, "Demand should be non-negative");
110 // Defensive: adjust for imprecision in event counting
111 if (demand < 0) {
112 demand = 0;
113 }
114 float old_rate = _demand_rate_estimate.padded_average();
115 float rate = ((float)demand)/inter_sweep_current;
116 _demand_rate_estimate.sample(rate);
117 float new_rate = _demand_rate_estimate.padded_average();
118 ssize_t old_desired = _desired;
119 _desired = (ssize_t)(new_rate * (inter_sweep_estimate
120 + CMSExtrapolateSweep
121 ? intra_sweep_estimate
122 : 0.0));
123 if (PrintFLSStatistics > 1) {
124 gclog_or_tty->print_cr("demand: %d, old_rate: %f, current_rate: %f, new_rate: %f, old_desired: %d, new_desired: %d",
125 demand, old_rate, rate, new_rate, old_desired, _desired);
126 }
127 }
128 }
129
130 ssize_t desired() const { return _desired; }
131 void set_desired(ssize_t v) { _desired = v; }
132
133 ssize_t coalDesired() const { return _coalDesired; }
134 void set_coalDesired(ssize_t v) { _coalDesired = v; }
135
136 ssize_t surplus() const { return _surplus; }
137 void set_surplus(ssize_t v) { _surplus = v; }
138 void increment_surplus() { _surplus++; }
139 void decrement_surplus() { _surplus--; }
140
141 ssize_t bfrSurp() const { return _bfrSurp; }
142 void set_bfrSurp(ssize_t v) { _bfrSurp = v; }
143 ssize_t prevSweep() const { return _prevSweep; }
144 void set_prevSweep(ssize_t v) { _prevSweep = v; }
145 ssize_t beforeSweep() const { return _beforeSweep; }
146 void set_beforeSweep(ssize_t v) { _beforeSweep = v; }
147
148 ssize_t coalBirths() const { return _coalBirths; }
149 void set_coalBirths(ssize_t v) { _coalBirths = v; }
150 void increment_coalBirths() { _coalBirths++; }
151
152 ssize_t coalDeaths() const { return _coalDeaths; }
153 void set_coalDeaths(ssize_t v) { _coalDeaths = v; }
154 void increment_coalDeaths() { _coalDeaths++; }
155
156 ssize_t splitBirths() const { return _splitBirths; }
157 void set_splitBirths(ssize_t v) { _splitBirths = v; }
158 void increment_splitBirths() { _splitBirths++; }
159
160 ssize_t splitDeaths() const { return _splitDeaths; }
161 void set_splitDeaths(ssize_t v) { _splitDeaths = v; }
162 void increment_splitDeaths() { _splitDeaths++; }
163
164 NOT_PRODUCT(
165 size_t returnedBytes() const { return _returnedBytes; }
166 void set_returnedBytes(size_t v) { _returnedBytes = v; }
167 )
168 };
169
170 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP