1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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,
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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/genRemSet.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 GCPolicyCounters* _gc_policy_counters;
62
63 virtual void initialize_alignments() = 0;
64 virtual void initialize_flags();
65 virtual void initialize_size_info();
66
67 DEBUG_ONLY(virtual void assert_flags();)
68 DEBUG_ONLY(virtual void assert_size_info();)
69
70 size_t _initial_heap_byte_size;
71 size_t _max_heap_byte_size;
72 size_t _min_heap_byte_size;
73
74 size_t _space_alignment;
75 size_t _heap_alignment;
76
77 // Needed to keep information if MaxHeapSize was set on the command line
78 // when the flag value is aligned etc by ergonomics.
79 bool _max_heap_size_cmdline;
80
81 // The sizing of the heap is controlled by a sizing policy.
82 AdaptiveSizePolicy* _size_policy;
83
84 // Set to true when policy wants soft refs cleared.
85 // Reset to false by gc after it clears all soft refs.
86 bool _should_clear_all_soft_refs;
87
88 // Set to true by the GC if the just-completed gc cleared all
89 // softrefs. This is set to true whenever a gc clears all softrefs, and
90 // set to false each time gc returns to the mutator. For example, in the
91 // ParallelScavengeHeap case the latter would be done toward the end of
92 // mem_allocate() where it returns op.result()
93 bool _all_soft_refs_clear;
94
95 CollectorPolicy();
96
97 public:
98 virtual void initialize_all() {
99 initialize_alignments();
100 initialize_flags();
101 initialize_size_info();
102 }
103
104 // Return maximum heap alignment that may be imposed by the policy.
105 static size_t compute_heap_alignment();
106
107 size_t space_alignment() { return _space_alignment; }
108 size_t heap_alignment() { return _heap_alignment; }
109
110 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
111 size_t max_heap_byte_size() { return _max_heap_byte_size; }
112 size_t min_heap_byte_size() { return _min_heap_byte_size; }
113
114 AdaptiveSizePolicy* size_policy() { return _size_policy; }
115 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
116 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
117 // Returns the current value of _should_clear_all_soft_refs.
118 // _should_clear_all_soft_refs is set to false as a side effect.
119 bool use_should_clear_all_soft_refs(bool v);
120 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
121 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
122
123 // Called by the GC after Soft Refs have been cleared to indicate
124 // that the request in _should_clear_all_soft_refs has been fulfilled.
125 void cleared_all_soft_refs();
126
127 // Identification methods.
128 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
129 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
130 #if INCLUDE_ALL_GCS
131 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
132 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
133 #endif // INCLUDE_ALL_GCS
134 // Note that these are not virtual.
135 bool is_generation_policy() { return as_generation_policy() != NULL; }
136 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
137 #if INCLUDE_ALL_GCS
138 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
139 bool is_g1_policy() { return as_g1_policy() != NULL; }
140 #else // INCLUDE_ALL_GCS
141 bool is_concurrent_mark_sweep_policy() { return false; }
142 bool is_g1_policy() { return false; }
143 #endif // INCLUDE_ALL_GCS
144
145
146 virtual GenRemSet* create_rem_set(MemRegion reserved);
147
148 // This method controls how a collector satisfies a request
149 // for a block of memory. "gc_time_limit_was_exceeded" will
150 // be set to true if the adaptive size policy determine that
151 // an excessive amount of time is being spent doing collections
152 // and caused a NULL to be returned. If a NULL is not returned,
153 // "gc_time_limit_was_exceeded" has an undefined meaning.
154 virtual HeapWord* mem_allocate_work(size_t size,
155 bool is_tlab,
156 bool* gc_overhead_limit_was_exceeded) = 0;
157
158 // This method controls how a collector handles one or more
159 // of its generations being fully allocated.
160 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
161 // This method controls how a collector handles a metadata allocation
162 // failure.
163 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
164 size_t size,
165 Metaspace::MetadataType mdtype);
166
167 // Performance Counter support
168 GCPolicyCounters* counters() { return _gc_policy_counters; }
169
170 // Create the jstat counters for the GC policy. By default, policy's
171 // don't have associated counters, and we complain if this is invoked.
172 virtual void initialize_gc_policy_counters() {
173 ShouldNotReachHere();
174 }
175
176 // Do any updates required to global flags that are due to heap initialization
177 // changes
178 virtual void post_heap_initialize() = 0;
179 };
180
181 class ClearedAllSoftRefs : public StackObj {
182 bool _clear_all_soft_refs;
183 CollectorPolicy* _collector_policy;
184 public:
185 ClearedAllSoftRefs(bool clear_all_soft_refs,
186 CollectorPolicy* collector_policy) :
187 _clear_all_soft_refs(clear_all_soft_refs),
188 _collector_policy(collector_policy) {}
189
190 ~ClearedAllSoftRefs() {
191 if (_clear_all_soft_refs) {
192 _collector_policy->cleared_all_soft_refs();
193 }
194 }
195 };
196
197 class GenCollectorPolicy : public CollectorPolicy {
198 friend class TestGenCollectorPolicy;
199 friend class VMStructs;
200 protected:
201 size_t _min_young_size;
202 size_t _initial_young_size;
203 size_t _max_young_size;
204 size_t _min_old_size;
205 size_t _initial_old_size;
206 size_t _max_old_size;
207
208 // _gen_alignment and _space_alignment will have the same value most of the
209 // time. When using large pages they can differ.
210 size_t _gen_alignment;
211
212 GenerationSpec* _young_gen_spec;
213 GenerationSpec* _old_gen_spec;
214
215 // Return true if an allocation should be attempted in the older generation
216 // if it fails in the younger generation. Return false, otherwise.
217 virtual bool should_try_older_generation_allocation(size_t word_size) const;
218
219 void initialize_flags();
220 void initialize_size_info();
221
222 DEBUG_ONLY(void assert_flags();)
223 DEBUG_ONLY(void assert_size_info();)
224
225 // Try to allocate space by expanding the heap.
226 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
227
228 // Compute max heap alignment.
229 size_t compute_max_alignment();
230
231 // Scale the base_size by NewRatio according to
232 // result = base_size / (NewRatio + 1)
233 // and align by min_alignment()
234 size_t scale_by_NewRatio_aligned(size_t base_size);
235
236 // Bound the value by the given maximum minus the min_alignment.
237 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
238
239 public:
240 GenCollectorPolicy();
241
242 // Accessors
243 size_t min_young_size() { return _min_young_size; }
244 size_t initial_young_size() { return _initial_young_size; }
245 size_t max_young_size() { return _max_young_size; }
246 size_t gen_alignment() { return _gen_alignment; }
247 size_t min_old_size() { return _min_old_size; }
248 size_t initial_old_size() { return _initial_old_size; }
249 size_t max_old_size() { return _max_old_size; }
250
251 GenerationSpec* young_gen_spec() const {
252 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");
253 return _young_gen_spec;
254 }
255
256 GenerationSpec* old_gen_spec() const {
257 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");
258 return _old_gen_spec;
259 }
260
261 virtual GenCollectorPolicy* as_generation_policy() { return this; }
262
263 virtual void initialize_generations() { };
264
265 virtual void initialize_all() {
266 CollectorPolicy::initialize_all();
267 initialize_generations();
268 }
269
270 size_t young_gen_size_lower_bound();
271
272 size_t old_gen_size_lower_bound();
273
274 HeapWord* mem_allocate_work(size_t size,
275 bool is_tlab,
276 bool* gc_overhead_limit_was_exceeded);
277
278 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
279
280 // Adaptive size policy
281 virtual void initialize_size_policy(size_t init_eden_size,
282 size_t init_promo_size,
283 size_t init_survivor_size);
284
285 virtual void post_heap_initialize() {
286 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info");
287 }
288 };
289
290 class MarkSweepPolicy : public GenCollectorPolicy {
291 protected:
292 void initialize_alignments();
293 void initialize_generations();
294
295 public:
296 MarkSweepPolicy() {}
297
298 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
299
300 void initialize_gc_policy_counters();
301 };
302
303 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP