1 /*
2 * Copyright Amazon.com Inc. 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 */
24
25 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHGENERATION_HPP
26 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHGENERATION_HPP
27
28 #include "memory/allocation.hpp"
29 #include "gc/shenandoah/heuristics/shenandoahSpaceInfo.hpp"
30 #include "gc/shenandoah/shenandoahGenerationType.hpp"
31 #include "gc/shenandoah/shenandoahLock.hpp"
32 #include "gc/shenandoah/shenandoahMarkingContext.hpp"
33
34 class ShenandoahCollectionSet;
35 class ShenandoahHeap;
36 class ShenandoahHeapRegion;
37 class ShenandoahHeapRegionClosure;
38 class ShenandoahHeuristics;
39 class ShenandoahMode;
40 class ShenandoahReferenceProcessor;
41
42
43 class ShenandoahGeneration : public CHeapObj<mtGC>, public ShenandoahSpaceInfo {
44 friend class VMStructs;
45 private:
46 ShenandoahGenerationType const _type;
47
48 // Marking task queues and completeness
49 ShenandoahObjToScanQueueSet* _task_queues;
50 ShenandoahSharedFlag _is_marking_complete;
51
52 ShenandoahReferenceProcessor* const _ref_processor;
53
54 size_t _affiliated_region_count;
55
56 // How much free memory is left in the last region of humongous objects.
57 // This is _not_ included in used, but it _is_ deducted from available,
58 // which gives the heuristics a more accurate view of how much memory remains
59 // for allocation. This figure is also included the heap status logging.
60 // The units are bytes. The value is only changed on a safepoint or under the
61 // heap lock.
62 size_t _humongous_waste;
63
64 // Bytes reserved within this generation to hold evacuated objects from the collection set
65 size_t _evacuation_reserve;
66
67 protected:
68 // Usage
69
70 volatile size_t _used;
71 volatile size_t _bytes_allocated_since_gc_start;
72 size_t _max_capacity;
73 size_t _soft_max_capacity;
74
75 ShenandoahHeuristics* _heuristics;
76
77 private:
78 // Compute evacuation budgets prior to choosing collection set.
79 void compute_evacuation_budgets(ShenandoahHeap* heap);
80
81 // Adjust evacuation budgets after choosing collection set.
82 void adjust_evacuation_budgets(ShenandoahHeap* heap,
83 ShenandoahCollectionSet* collection_set);
84
85 // Preselect for possible inclusion into the collection set exactly the most
86 // garbage-dense regions, including those that satisfy criteria 1 & 2 below,
87 // and whose live bytes will fit within old_available budget:
88 // Criterion 1. region age >= tenuring threshold
89 // Criterion 2. region garbage percentage > ShenandoahOldGarbageThreshold
90 //
91 // Identifies regions eligible for promotion in place,
92 // being those of at least tenuring_threshold age that have lower garbage
93 // density.
94 //
95 // Updates promotion_potential and pad_for_promote_in_place fields
96 // of the heap. Returns bytes of live object memory in the preselected
97 // regions, which are marked in the preselected_regions() indicator
98 // array of the heap's collection set, which should be initialized
99 // to false.
100 size_t select_aged_regions(size_t old_available);
101
102 size_t available(size_t capacity) const;
103
104 public:
105 ShenandoahGeneration(ShenandoahGenerationType type,
106 uint max_workers,
107 size_t max_capacity,
108 size_t soft_max_capacity);
109 ~ShenandoahGeneration();
110
111 bool is_young() const { return _type == YOUNG; }
112 bool is_old() const { return _type == OLD; }
113 bool is_global() const { return _type == GLOBAL || _type == NON_GEN; }
114
115 // see description in field declaration
116 void set_evacuation_reserve(size_t new_val);
117 size_t get_evacuation_reserve() const;
118 void augment_evacuation_reserve(size_t increment);
119
120 inline ShenandoahGenerationType type() const { return _type; }
121
122 virtual ShenandoahHeuristics* heuristics() const { return _heuristics; }
123
124 ShenandoahReferenceProcessor* ref_processor() { return _ref_processor; }
125
126 virtual ShenandoahHeuristics* initialize_heuristics(ShenandoahMode* gc_mode);
127
128 size_t soft_max_capacity() const override { return _soft_max_capacity; }
129 size_t max_capacity() const override { return _max_capacity; }
130 virtual size_t used_regions() const;
131 virtual size_t used_regions_size() const;
132 virtual size_t free_unaffiliated_regions() const;
133 size_t used() const override { return _used; }
134 size_t available() const override;
135 size_t available_with_reserve() const;
136 size_t used_including_humongous_waste() const {
137 return used() + get_humongous_waste();
138 }
139
140 // Returns the memory available based on the _soft_ max heap capacity (soft_max_heap - used).
141 // The soft max heap size may be adjusted lower than the max heap size to cause the trigger
142 // to believe it has less memory available than is _really_ available. Lowering the soft
143 // max heap size will cause the adaptive heuristic to run more frequent cycles.
144 size_t soft_available() const override;
145
146 size_t bytes_allocated_since_gc_start() const override;
147 void reset_bytes_allocated_since_gc_start();
148 void increase_allocated(size_t bytes);
149
150 // These methods change the capacity of the region by adding or subtracting the given number of bytes from the current
151 // capacity.
152 void increase_capacity(size_t increment);
153 void decrease_capacity(size_t decrement);
154
155 void log_status(const char* msg) const;
156
157 // Used directly by FullGC
158 void reset_mark_bitmap();
159
160 // Used by concurrent and degenerated GC to reset remembered set.
161 void swap_remembered_set();
162
163 // Update the read cards with the state of the write table (write table is not cleared).
164 void merge_write_table();
165
166 // Called before init mark, expected to prepare regions for marking.
167 virtual void prepare_gc();
168
169 // Called during final mark, chooses collection set, rebuilds free set.
170 virtual void prepare_regions_and_collection_set(bool concurrent);
171
172 // Cancel marking (used by Full collect and when cancelling cycle).
173 virtual void cancel_marking();
174
175 // Return true if this region is affiliated with this generation.
176 virtual bool contains(ShenandoahHeapRegion* region) const = 0;
177
178 // Return true if this object is affiliated with this generation.
179 virtual bool contains(oop obj) const = 0;
180
181 // Apply closure to all regions affiliated with this generation.
182 virtual void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* cl) = 0;
183
184 // Apply closure to all regions affiliated with this generation (include free regions);
185 virtual void parallel_region_iterate_free(ShenandoahHeapRegionClosure* cl);
186
187 // Apply closure to all regions affiliated with this generation (single threaded).
188 virtual void heap_region_iterate(ShenandoahHeapRegionClosure* cl) = 0;
189
190 // This is public to support cancellation of marking when a Full cycle is started.
191 virtual void set_concurrent_mark_in_progress(bool in_progress) = 0;
192
193 // Check the bitmap only for regions belong to this generation.
194 bool is_bitmap_clear();
195
196 // We need to track the status of marking for different generations.
197 bool is_mark_complete();
198 virtual void set_mark_complete();
199 virtual void set_mark_incomplete();
200
201 ShenandoahMarkingContext* complete_marking_context();
202
203 // Task queues
204 ShenandoahObjToScanQueueSet* task_queues() const { return _task_queues; }
205 virtual void reserve_task_queues(uint workers);
206 virtual ShenandoahObjToScanQueueSet* old_gen_task_queues() const;
207
208 // Scan remembered set at start of concurrent young-gen marking.
209 void scan_remembered_set(bool is_concurrent);
210
211 // Return the updated value of affiliated_region_count
212 size_t increment_affiliated_region_count();
213
214 // Return the updated value of affiliated_region_count
215 size_t decrement_affiliated_region_count();
216
217 // Return the updated value of affiliated_region_count
218 size_t increase_affiliated_region_count(size_t delta);
219
220 // Return the updated value of affiliated_region_count
221 size_t decrease_affiliated_region_count(size_t delta);
222
223 void establish_usage(size_t num_regions, size_t num_bytes, size_t humongous_waste);
224
225 void increase_used(size_t bytes);
226 void decrease_used(size_t bytes);
227
228 void increase_humongous_waste(size_t bytes);
229 void decrease_humongous_waste(size_t bytes);
230 size_t get_humongous_waste() const { return _humongous_waste; }
231
232 virtual bool is_concurrent_mark_in_progress() = 0;
233 void confirm_heuristics_mode();
234
235 virtual void record_success_concurrent(bool abbreviated);
236 };
237
238 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHGENERATION_HPP