1 /*
2 * Copyright (c) 2018, 2019, Red Hat, 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
26 #define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
27
28 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
29 #include "gc/shenandoah/heuristics/shenandoahSpaceInfo.hpp"
30 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
31 #include "utilities/numberSeq.hpp"
32
33 class ShenandoahAllocationRate : public CHeapObj<mtGC> {
34 public:
35 explicit ShenandoahAllocationRate();
36 void allocation_counter_reset();
37
38 double sample(size_t allocated);
39
40 double upper_bound(double sds) const;
41 bool is_spiking(double rate, double threshold) const;
42
43 private:
44
45 double instantaneous_rate(double time, size_t allocated) const;
46
47 double _last_sample_time;
48 size_t _last_sample_value;
49 double _interval_sec;
50 TruncatedSeq _rate;
51 TruncatedSeq _rate_avg;
52 };
53
54 /*
55 * The adaptive heuristic tracks the allocation behavior and average cycle
56 * time of the application. It attempts to start a cycle with enough time
57 * to complete before the available memory is exhausted. It errors on the
58 * side of starting cycles early to avoid allocation failures (degenerated
59 * cycles).
60 *
61 * This heuristic limits the number of regions for evacuation such that the
62 * evacuation reserve is respected. This helps it avoid allocation failures
121 double _margin_of_error_sd;
122
123 // The allocation spike threshold is expressed in standard deviations.
124 // If the standard deviation of the most recent sample of the allocation
125 // rate exceeds this threshold, a GC cycle is started. As this value
126 // decreases the sensitivity to allocation spikes increases. In other
127 // words, lowering the spike threshold will tend to increase the number
128 // of concurrent GCs.
129 double _spike_threshold_sd;
130
131 // Remember which trigger is responsible for the last GC cycle. When the
132 // outcome of the cycle is evaluated we will adjust the parameters for the
133 // corresponding triggers. Note that successful outcomes will raise
134 // the spike threshold and lower the margin of error.
135 Trigger _last_trigger;
136
137 // Keep track of the available memory at the end of a GC cycle. This
138 // establishes what is 'normal' for the application and is used as a
139 // source of feedback to adjust trigger parameters.
140 TruncatedSeq _available;
141 };
142
143 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
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1 /*
2 * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #ifndef SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
27 #define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
28
29 #include "memory/allocation.hpp"
30 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
31 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
32 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
33 #include "utilities/numberSeq.hpp"
34
35 class ShenandoahAllocationRate : public CHeapObj<mtGC> {
36 public:
37 explicit ShenandoahAllocationRate();
38 void allocation_counter_reset();
39
40 double sample(size_t allocated);
41
42 double upper_bound(double sds) const;
43 bool is_spiking(double rate, double threshold) const;
44 private:
45
46 double instantaneous_rate(double time, size_t allocated) const;
47
48 double _last_sample_time;
49 size_t _last_sample_value;
50 double _interval_sec;
51 TruncatedSeq _rate;
52 TruncatedSeq _rate_avg;
53 };
54
55 /*
56 * The adaptive heuristic tracks the allocation behavior and average cycle
57 * time of the application. It attempts to start a cycle with enough time
58 * to complete before the available memory is exhausted. It errors on the
59 * side of starting cycles early to avoid allocation failures (degenerated
60 * cycles).
61 *
62 * This heuristic limits the number of regions for evacuation such that the
63 * evacuation reserve is respected. This helps it avoid allocation failures
122 double _margin_of_error_sd;
123
124 // The allocation spike threshold is expressed in standard deviations.
125 // If the standard deviation of the most recent sample of the allocation
126 // rate exceeds this threshold, a GC cycle is started. As this value
127 // decreases the sensitivity to allocation spikes increases. In other
128 // words, lowering the spike threshold will tend to increase the number
129 // of concurrent GCs.
130 double _spike_threshold_sd;
131
132 // Remember which trigger is responsible for the last GC cycle. When the
133 // outcome of the cycle is evaluated we will adjust the parameters for the
134 // corresponding triggers. Note that successful outcomes will raise
135 // the spike threshold and lower the margin of error.
136 Trigger _last_trigger;
137
138 // Keep track of the available memory at the end of a GC cycle. This
139 // establishes what is 'normal' for the application and is used as a
140 // source of feedback to adjust trigger parameters.
141 TruncatedSeq _available;
142
143 // A conservative minimum threshold of free space that we'll try to maintain when possible.
144 // For example, we might trigger a concurrent gc if we are likely to drop below
145 // this threshold, or we might consider this when dynamically resizing generations
146 // in the generational case. Controlled by global flag ShenandoahMinFreeThreshold.
147 size_t min_free_threshold();
148 };
149
150 #endif // SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHADAPTIVEHEURISTICS_HPP
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