Tue, 08 Aug 2017 15:57:29 +0800
merge
1 /*
2 * Copyright (c) 2001, 2014, 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.
18 *
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 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP
28 #include "utilities/macros.hpp"
29 #include "memory/allocation.hpp"
30 #include "utilities/globalDefinitions.hpp"
31 #include "gc_implementation/shared/gcUtil.hpp"
33 class AllocationStats VALUE_OBJ_CLASS_SPEC {
34 // A duration threshold (in ms) used to filter
35 // possibly unreliable samples.
36 static float _threshold;
38 // We measure the demand between the end of the previous sweep and
39 // beginning of this sweep:
40 // Count(end_last_sweep) - Count(start_this_sweep)
41 // + split_births(between) - split_deaths(between)
42 // The above number divided by the time since the end of the
43 // previous sweep gives us a time rate of demand for blocks
44 // of this size. We compute a padded average of this rate as
45 // our current estimate for the time rate of demand for blocks
46 // of this size. Similarly, we keep a padded average for the time
47 // between sweeps. Our current estimate for demand for blocks of
48 // this size is then simply computed as the product of these two
49 // estimates.
50 AdaptivePaddedAverage _demand_rate_estimate;
52 ssize_t _desired; // Demand stimate computed as described above
53 ssize_t _coal_desired; // desired +/- small-percent for tuning coalescing
55 ssize_t _surplus; // count - (desired +/- small-percent),
56 // used to tune splitting in best fit
57 ssize_t _bfr_surp; // surplus at start of current sweep
58 ssize_t _prev_sweep; // count from end of previous sweep
59 ssize_t _before_sweep; // count from before current sweep
60 ssize_t _coal_births; // additional chunks from coalescing
61 ssize_t _coal_deaths; // loss from coalescing
62 ssize_t _split_births; // additional chunks from splitting
63 ssize_t _split_deaths; // loss from splitting
64 size_t _returned_bytes; // number of bytes returned to list.
65 public:
66 void initialize(bool split_birth = false) {
67 AdaptivePaddedAverage* dummy =
68 new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight,
69 CMS_FLSPadding);
70 _desired = 0;
71 _coal_desired = 0;
72 _surplus = 0;
73 _bfr_surp = 0;
74 _prev_sweep = 0;
75 _before_sweep = 0;
76 _coal_births = 0;
77 _coal_deaths = 0;
78 _split_births = (split_birth ? 1 : 0);
79 _split_deaths = 0;
80 _returned_bytes = 0;
81 }
83 AllocationStats() {
84 initialize();
85 }
87 // The rate estimate is in blocks per second.
88 void compute_desired(size_t count,
89 float inter_sweep_current,
90 float inter_sweep_estimate,
91 float intra_sweep_estimate) {
92 // If the latest inter-sweep time is below our granularity
93 // of measurement, we may call in here with
94 // inter_sweep_current == 0. However, even for suitably small
95 // but non-zero inter-sweep durations, we may not trust the accuracy
96 // of accumulated data, since it has not been "integrated"
97 // (read "low-pass-filtered") long enough, and would be
98 // vulnerable to noisy glitches. In such cases, we
99 // ignore the current sample and use currently available
100 // historical estimates.
101 assert(prev_sweep() + split_births() + coal_births() // "Total Production Stock"
102 >= split_deaths() + coal_deaths() + (ssize_t)count, // "Current stock + depletion"
103 "Conservation Principle");
104 if (inter_sweep_current > _threshold) {
105 ssize_t demand = prev_sweep() - (ssize_t)count + split_births() + coal_births()
106 - split_deaths() - coal_deaths();
107 assert(demand >= 0,
108 err_msg("Demand (" SSIZE_FORMAT ") should be non-negative for "
109 PTR_FORMAT " (size=" SIZE_FORMAT ")",
110 demand, p2i(this), count));
111 // Defensive: adjust for imprecision in event counting
112 if (demand < 0) {
113 demand = 0;
114 }
115 float old_rate = _demand_rate_estimate.padded_average();
116 float rate = ((float)demand)/inter_sweep_current;
117 _demand_rate_estimate.sample(rate);
118 float new_rate = _demand_rate_estimate.padded_average();
119 ssize_t old_desired = _desired;
120 float delta_ise = (CMSExtrapolateSweep ? intra_sweep_estimate : 0.0);
121 _desired = (ssize_t)(new_rate * (inter_sweep_estimate + delta_ise));
122 if (PrintFLSStatistics > 1) {
123 gclog_or_tty->print_cr(
124 "demand: " SSIZE_FORMAT ", old_rate: %f, current_rate: %f, new_rate: %f, old_desired: " SSIZE_FORMAT ", new_desired: " SSIZE_FORMAT,
125 demand, old_rate, rate, new_rate, old_desired, _desired);
126 }
127 }
128 }
130 ssize_t desired() const { return _desired; }
131 void set_desired(ssize_t v) { _desired = v; }
133 ssize_t coal_desired() const { return _coal_desired; }
134 void set_coal_desired(ssize_t v) { _coal_desired = v; }
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--; }
141 ssize_t bfr_surp() const { return _bfr_surp; }
142 void set_bfr_surp(ssize_t v) { _bfr_surp = v; }
143 ssize_t prev_sweep() const { return _prev_sweep; }
144 void set_prev_sweep(ssize_t v) { _prev_sweep = v; }
145 ssize_t before_sweep() const { return _before_sweep; }
146 void set_before_sweep(ssize_t v) { _before_sweep = v; }
148 ssize_t coal_births() const { return _coal_births; }
149 void set_coal_births(ssize_t v) { _coal_births = v; }
150 void increment_coal_births() { _coal_births++; }
152 ssize_t coal_deaths() const { return _coal_deaths; }
153 void set_coal_deaths(ssize_t v) { _coal_deaths = v; }
154 void increment_coal_deaths() { _coal_deaths++; }
156 ssize_t split_births() const { return _split_births; }
157 void set_split_births(ssize_t v) { _split_births = v; }
158 void increment_split_births() { _split_births++; }
160 ssize_t split_deaths() const { return _split_deaths; }
161 void set_split_deaths(ssize_t v) { _split_deaths = v; }
162 void increment_split_deaths() { _split_deaths++; }
164 NOT_PRODUCT(
165 size_t returned_bytes() const { return _returned_bytes; }
166 void set_returned_bytes(size_t v) { _returned_bytes = v; }
167 )
168 };
170 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP