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.
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_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 class ShenandoahCollectorPolicy;
55 #endif // INCLUDE_ALL_GCS
56
57 class GCPolicyCounters;
58 class MarkSweepPolicy;
59
60 class CollectorPolicy : public CHeapObj<mtGC> {
61 protected:
62 GCPolicyCounters* _gc_policy_counters;
63
64 virtual void initialize_alignments() = 0;
65 virtual void initialize_flags();
66 virtual void initialize_size_info();
67
68 DEBUG_ONLY(virtual void assert_flags();)
69 DEBUG_ONLY(virtual void assert_size_info();)
70
71 size_t _initial_heap_byte_size;
72 size_t _max_heap_byte_size;
73 size_t _min_heap_byte_size;
74
75 size_t _space_alignment;
76 size_t _heap_alignment;
77
78 // Needed to keep information if MaxHeapSize was set on the command line
79 // when the flag value is aligned etc by ergonomics.
80 bool _max_heap_size_cmdline;
81
82 // The sizing of the heap is controlled by a sizing policy.
83 AdaptiveSizePolicy* _size_policy;
84
85 // Set to true when policy wants soft refs cleared.
86 // Reset to false by gc after it clears all soft refs.
87 bool _should_clear_all_soft_refs;
88
89 // Set to true by the GC if the just-completed gc cleared all
90 // softrefs. This is set to true whenever a gc clears all softrefs, and
91 // set to false each time gc returns to the mutator. For example, in the
92 // ParallelScavengeHeap case the latter would be done toward the end of
93 // mem_allocate() where it returns op.result()
94 bool _all_soft_refs_clear;
95
96 CollectorPolicy();
97
98 public:
99 virtual void initialize_all() {
100 initialize_alignments();
101 initialize_flags();
102 initialize_size_info();
103 }
104
105 // Return maximum heap alignment that may be imposed by the policy.
106 static size_t compute_heap_alignment();
107
108 size_t space_alignment() { return _space_alignment; }
109 size_t heap_alignment() { return _heap_alignment; }
110
111 size_t initial_heap_byte_size() { return _initial_heap_byte_size; }
112 size_t max_heap_byte_size() { return _max_heap_byte_size; }
113 size_t min_heap_byte_size() { return _min_heap_byte_size; }
114
115 AdaptiveSizePolicy* size_policy() { return _size_policy; }
116 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
117 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
118 // Returns the current value of _should_clear_all_soft_refs.
119 // _should_clear_all_soft_refs is set to false as a side effect.
120 bool use_should_clear_all_soft_refs(bool v);
121 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
122 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
123
124 // Called by the GC after Soft Refs have been cleared to indicate
125 // that the request in _should_clear_all_soft_refs has been fulfilled.
126 void cleared_all_soft_refs();
127
128 // Identification methods.
129 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
130 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
131 #if INCLUDE_ALL_GCS
132 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
133 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
134 #endif // INCLUDE_ALL_GCS
135 // Note that these are not virtual.
136 bool is_generation_policy() { return as_generation_policy() != NULL; }
137 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
138 #if INCLUDE_ALL_GCS
139 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
140 bool is_g1_policy() { return as_g1_policy() != NULL; }
141 #else // INCLUDE_ALL_GCS
142 bool is_concurrent_mark_sweep_policy() { return false; }
143 bool is_g1_policy() { return false; }
144 bool is_pgc_policy() { return false; }
145 #endif // INCLUDE_ALL_GCS
146
147
148 virtual GenRemSet* create_rem_set(MemRegion reserved);
149
150 // This method controls how a collector satisfies a request
151 // for a block of memory. "gc_time_limit_was_exceeded" will
152 // be set to true if the adaptive size policy determine that
153 // an excessive amount of time is being spent doing collections
154 // and caused a NULL to be returned. If a NULL is not returned,
155 // "gc_time_limit_was_exceeded" has an undefined meaning.
156 virtual HeapWord* mem_allocate_work(size_t size,
157 bool is_tlab,
158 bool* gc_overhead_limit_was_exceeded) = 0;
159
160 // This method controls how a collector handles one or more
161 // of its generations being fully allocated.
162 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
163 // This method controls how a collector handles a metadata allocation
164 // failure.
165 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
166 size_t size,
167 Metaspace::MetadataType mdtype);
168
169 // Performance Counter support
170 GCPolicyCounters* counters() { return _gc_policy_counters; }
171
172 // Create the jstat counters for the GC policy. By default, policy's
173 // don't have associated counters, and we complain if this is invoked.
174 virtual void initialize_gc_policy_counters() {
175 ShouldNotReachHere();
176 }
177
178 // Do any updates required to global flags that are due to heap initialization
179 // changes
180 virtual void post_heap_initialize() = 0;
181 };
182
183 class ClearedAllSoftRefs : public StackObj {
184 bool _clear_all_soft_refs;
185 CollectorPolicy* _collector_policy;
186 public:
187 ClearedAllSoftRefs(bool clear_all_soft_refs,
188 CollectorPolicy* collector_policy) :
189 _clear_all_soft_refs(clear_all_soft_refs),
190 _collector_policy(collector_policy) {}
191
192 ~ClearedAllSoftRefs() {
193 if (_clear_all_soft_refs) {
194 _collector_policy->cleared_all_soft_refs();
195 }
196 }
197 };
198
199 class GenCollectorPolicy : public CollectorPolicy {
200 friend class TestGenCollectorPolicy;
201 friend class VMStructs;
202 protected:
203 size_t _min_young_size;
204 size_t _initial_young_size;
205 size_t _max_young_size;
206 size_t _min_old_size;
207 size_t _initial_old_size;
208 size_t _max_old_size;
209
210 // _gen_alignment and _space_alignment will have the same value most of the
211 // time. When using large pages they can differ.
212 size_t _gen_alignment;
213
214 GenerationSpec* _young_gen_spec;
215 GenerationSpec* _old_gen_spec;
216
217 // Return true if an allocation should be attempted in the older generation
218 // if it fails in the younger generation. Return false, otherwise.
219 virtual bool should_try_older_generation_allocation(size_t word_size) const;
220
221 void initialize_flags();
222 void initialize_size_info();
223
224 DEBUG_ONLY(void assert_flags();)
225 DEBUG_ONLY(void assert_size_info();)
226
227 // Try to allocate space by expanding the heap.
228 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
229
230 // Compute max heap alignment.
231 size_t compute_max_alignment();
232
233 // Scale the base_size by NewRatio according to
234 // result = base_size / (NewRatio + 1)
235 // and align by min_alignment()
236 size_t scale_by_NewRatio_aligned(size_t base_size);
237
238 // Bound the value by the given maximum minus the min_alignment.
239 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
240
241 public:
242 GenCollectorPolicy();
243
244 // Accessors
245 size_t min_young_size() { return _min_young_size; }
246 size_t initial_young_size() { return _initial_young_size; }
247 size_t max_young_size() { return _max_young_size; }
248 size_t gen_alignment() { return _gen_alignment; }
249 size_t min_old_size() { return _min_old_size; }
250 size_t initial_old_size() { return _initial_old_size; }
251 size_t max_old_size() { return _max_old_size; }
252
253 GenerationSpec* young_gen_spec() const {
254 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");
255 return _young_gen_spec;
256 }
257
258 GenerationSpec* old_gen_spec() const {
259 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");
260 return _old_gen_spec;
261 }
262
263 virtual GenCollectorPolicy* as_generation_policy() { return this; }
264
265 virtual void initialize_generations() { };
266
267 virtual void initialize_all() {
268 CollectorPolicy::initialize_all();
269 initialize_generations();
270 }
271
272 size_t young_gen_size_lower_bound();
273
274 size_t old_gen_size_lower_bound();
275
276 HeapWord* mem_allocate_work(size_t size,
277 bool is_tlab,
278 bool* gc_overhead_limit_was_exceeded);
279
280 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
281
282 // Adaptive size policy
283 virtual void initialize_size_policy(size_t init_eden_size,
284 size_t init_promo_size,
285 size_t init_survivor_size);
286
287 virtual void post_heap_initialize() {
288 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info");
289 }
290 };
291
292 class MarkSweepPolicy : public GenCollectorPolicy {
293 protected:
294 void initialize_alignments();
295 void initialize_generations();
296
297 public:
298 MarkSweepPolicy() {}
299
300 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
301
302 void initialize_gc_policy_counters();
303 };
304
305 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP