1 /*
2 * Copyright (c) 2001, 2016, 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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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_SHARED_COLLECTORPOLICY_HPP
26 #define SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP
27
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/cardTableRS.hpp"
30 #include "gc/shared/generationSpec.hpp"
31 #include "memory/allocation.hpp"
32 #include "utilities/macros.hpp"
33
34 // This class (or more correctly, subtypes of this class)
35 // are used to define global garbage collector attributes.
36 // This includes initialization of generations and any other
37 // shared resources they may need.
38 //
39 // In general, all flag adjustment and validation should be
40 // done in initialize_flags(), which is called prior to
41 // initialize_size_info().
42 //
43 // This class is not fully developed yet. As more collector(s)
44 // are added, it is expected that we will come across further
45 // behavior that requires global attention. The correct place
46 // to deal with those issues is this class.
47
48 // Forward declarations.
49 class GenCollectorPolicy;
50 class AdaptiveSizePolicy;
51 #if INCLUDE_ALL_GCS
52 class ConcurrentMarkSweepPolicy;
53 class G1CollectorPolicy;
54 #endif // INCLUDE_ALL_GCS
55
56 class GCPolicyCounters;
57 class MarkSweepPolicy;
58
59 class CollectorPolicy : public CHeapObj<mtGC> {
60 protected:
61 virtual void initialize_alignments() = 0;
62 virtual void initialize_flags();
63 virtual void initialize_size_info();
64
65 DEBUG_ONLY(virtual void assert_flags();)
66 DEBUG_ONLY(virtual void assert_size_info();)
67
68 size_t _initial_heap_byte_size;
69 size_t _max_heap_byte_size;
70 size_t _min_heap_byte_size;
71
72 size_t _space_alignment;
73 size_t _heap_alignment;
74
75 // Needed to keep information if MaxHeapSize was set on the command line
76 // when the flag value is aligned etc by ergonomics.
77 bool _max_heap_size_cmdline;
78
79 // The sizing of the heap is controlled by a sizing policy.
80 AdaptiveSizePolicy* _size_policy;
81
82 // Set to true when policy wants soft refs cleared.
83 // Reset to false by gc after it clears all soft refs.
84 bool _should_clear_all_soft_refs;
85
86 // Set to true by the GC if the just-completed gc cleared all
87 // softrefs. This is set to true whenever a gc clears all softrefs, and
88 // set to false each time gc returns to the mutator. For example, in the
89 // ParallelScavengeHeap case the latter would be done toward the end of
90 // mem_allocate() where it returns op.result()
91 bool _all_soft_refs_clear;
92
93 CollectorPolicy();
94
95 public:
96 virtual void initialize_all() {
97 initialize_alignments();
98 initialize_flags();
99 initialize_size_info();
100 }
101
102 // Return maximum heap alignment that may be imposed by the policy.
103 static size_t compute_heap_alignment();
104
105 size_t space_alignment() { return _space_alignment; }
106 size_t heap_alignment() { return _heap_alignment; }
107
108 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
109 size_t max_heap_byte_size() { return _max_heap_byte_size; }
110 size_t min_heap_byte_size() { return _min_heap_byte_size; }
111
112 AdaptiveSizePolicy* size_policy() { return _size_policy; }
113 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
114 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
115 // Returns the current value of _should_clear_all_soft_refs.
116 // _should_clear_all_soft_refs is set to false as a side effect.
117 bool use_should_clear_all_soft_refs(bool v);
118 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
119 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
120
121 // Called by the GC after Soft Refs have been cleared to indicate
122 // that the request in _should_clear_all_soft_refs has been fulfilled.
123 void cleared_all_soft_refs();
124
125 // Identification methods.
126 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
127 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
128 #if INCLUDE_ALL_GCS
129 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
130 #endif // INCLUDE_ALL_GCS
131 // Note that these are not virtual.
132 bool is_generation_policy() { return as_generation_policy() != NULL; }
133 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
134 #if INCLUDE_ALL_GCS
135 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
136 #else // INCLUDE_ALL_GCS
137 bool is_concurrent_mark_sweep_policy() { return false; }
138 #endif // INCLUDE_ALL_GCS
139
140
141 virtual CardTableRS* create_rem_set(MemRegion reserved);
142
143 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
144 size_t size,
145 Metaspace::MetadataType mdtype);
146 };
147
148 class ClearedAllSoftRefs : public StackObj {
149 bool _clear_all_soft_refs;
150 CollectorPolicy* _collector_policy;
151 public:
152 ClearedAllSoftRefs(bool clear_all_soft_refs,
153 CollectorPolicy* collector_policy) :
154 _clear_all_soft_refs(clear_all_soft_refs),
155 _collector_policy(collector_policy) {}
156
157 ~ClearedAllSoftRefs() {
158 if (_clear_all_soft_refs) {
159 _collector_policy->cleared_all_soft_refs();
160 }
161 }
162 };
163
164 class GenCollectorPolicy : public CollectorPolicy {
165 friend class TestGenCollectorPolicy;
166 friend class VMStructs;
167 protected:
168 size_t _min_young_size;
169 size_t _initial_young_size;
170 size_t _max_young_size;
171 size_t _min_old_size;
172 size_t _initial_old_size;
173 size_t _max_old_size;
174
175 // _gen_alignment and _space_alignment will have the same value most of the
176 // time. When using large pages they can differ.
177 size_t _gen_alignment;
178
179 GenerationSpec* _young_gen_spec;
180 GenerationSpec* _old_gen_spec;
181
182 GCPolicyCounters* _gc_policy_counters;
183
184 // Return true if an allocation should be attempted in the older generation
185 // if it fails in the younger generation. Return false, otherwise.
186 virtual bool should_try_older_generation_allocation(size_t word_size) const;
187
188 void initialize_flags();
189 void initialize_size_info();
190
191 DEBUG_ONLY(void assert_flags();)
192 DEBUG_ONLY(void assert_size_info();)
193
194 // Try to allocate space by expanding the heap.
195 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
196
197 // Compute max heap alignment.
198 size_t compute_max_alignment();
199
200 // Scale the base_size by NewRatio according to
201 // result = base_size / (NewRatio + 1)
202 // and align by min_alignment()
203 size_t scale_by_NewRatio_aligned(size_t base_size);
204
205 // Bound the value by the given maximum minus the min_alignment.
206 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
207
208 public:
209 GenCollectorPolicy();
210
211 // Accessors
212 size_t min_young_size() { return _min_young_size; }
213 size_t initial_young_size() { return _initial_young_size; }
214 size_t max_young_size() { return _max_young_size; }
215 size_t gen_alignment() { return _gen_alignment; }
216 size_t min_old_size() { return _min_old_size; }
217 size_t initial_old_size() { return _initial_old_size; }
218 size_t max_old_size() { return _max_old_size; }
219
220 GenerationSpec* young_gen_spec() const {
221 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");
222 return _young_gen_spec;
223 }
224
225 GenerationSpec* old_gen_spec() const {
226 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");
227 return _old_gen_spec;
228 }
229
230 // Performance Counter support
231 GCPolicyCounters* counters() { return _gc_policy_counters; }
232
233 // Create the jstat counters for the GC policy.
234 virtual void initialize_gc_policy_counters() = 0;
235
236 virtual GenCollectorPolicy* as_generation_policy() { return this; }
237
238 virtual void initialize_generations() { };
239
240 virtual void initialize_all() {
241 CollectorPolicy::initialize_all();
242 initialize_generations();
243 }
244
245 size_t young_gen_size_lower_bound();
246
247 size_t old_gen_size_lower_bound();
248
249 HeapWord* mem_allocate_work(size_t size,
250 bool is_tlab,
251 bool* gc_overhead_limit_was_exceeded);
252
253 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
254
255 // Adaptive size policy
256 virtual void initialize_size_policy(size_t init_eden_size,
257 size_t init_promo_size,
258 size_t init_survivor_size);
259 };
260
261 class MarkSweepPolicy : public GenCollectorPolicy {
262 protected:
263 void initialize_alignments();
264 void initialize_generations();
265
266 public:
267 MarkSweepPolicy() {}
268
269 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
270
271 void initialize_gc_policy_counters();
272 };
273
274 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP