1 /*
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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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13 * accompanied this code).
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24
25 #ifndef SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
26 #define SHARE_VM_MEMORY_COLLECTORPOLICY_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/barrierSet.hpp"
30 #include "memory/generationSpec.hpp"
31 #include "memory/genRemSet.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 enum Name {
115 CollectorPolicyKind,
116 GenCollectorPolicyKind,
117 ConcurrentMarkSweepPolicyKind,
118 G1CollectorPolicyKind
119 };
120
121 AdaptiveSizePolicy* size_policy() { return _size_policy; }
122 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
123 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
124 // Returns the current value of _should_clear_all_soft_refs.
125 // _should_clear_all_soft_refs is set to false as a side effect.
126 bool use_should_clear_all_soft_refs(bool v);
127 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
128 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
129
130 // Called by the GC after Soft Refs have been cleared to indicate
131 // that the request in _should_clear_all_soft_refs has been fulfilled.
132 void cleared_all_soft_refs();
133
134 // Identification methods.
135 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
136 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
137 #if INCLUDE_ALL_GCS
138 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
139 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
140 #endif // INCLUDE_ALL_GCS
141 // Note that these are not virtual.
142 bool is_generation_policy() { return as_generation_policy() != NULL; }
143 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
144 #if INCLUDE_ALL_GCS
145 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
146 bool is_g1_policy() { return as_g1_policy() != NULL; }
147 #else // INCLUDE_ALL_GCS
148 bool is_concurrent_mark_sweep_policy() { return false; }
149 bool is_g1_policy() { return false; }
150 #endif // INCLUDE_ALL_GCS
151
152
153 virtual BarrierSet::Name barrier_set_name() = 0;
154
155 // Create the remembered set (to cover the given reserved region,
156 // allowing breaking up into at most "max_covered_regions").
157 virtual GenRemSet* create_rem_set(MemRegion reserved,
158 int max_covered_regions);
159
160 // This method controls how a collector satisfies a request
161 // for a block of memory. "gc_time_limit_was_exceeded" will
162 // be set to true if the adaptive size policy determine that
163 // an excessive amount of time is being spent doing collections
164 // and caused a NULL to be returned. If a NULL is not returned,
165 // "gc_time_limit_was_exceeded" has an undefined meaning.
166 virtual HeapWord* mem_allocate_work(size_t size,
167 bool is_tlab,
168 bool* gc_overhead_limit_was_exceeded) = 0;
169
170 // This method controls how a collector handles one or more
171 // of its generations being fully allocated.
172 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
173 // This method controls how a collector handles a metadata allocation
174 // failure.
175 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
176 size_t size,
177 Metaspace::MetadataType mdtype);
178
179 // Performance Counter support
180 GCPolicyCounters* counters() { return _gc_policy_counters; }
181
182 // Create the jstat counters for the GC policy. By default, policy's
183 // don't have associated counters, and we complain if this is invoked.
184 virtual void initialize_gc_policy_counters() {
185 ShouldNotReachHere();
186 }
187
188 virtual CollectorPolicy::Name kind() {
189 return CollectorPolicy::CollectorPolicyKind;
190 }
191
192 // Returns true if a collector has eden space with soft end.
193 virtual bool has_soft_ended_eden() {
194 return false;
195 }
196
197 // Do any updates required to global flags that are due to heap initialization
198 // changes
199 virtual void post_heap_initialize() = 0;
200 };
201
202 class ClearedAllSoftRefs : public StackObj {
203 bool _clear_all_soft_refs;
204 CollectorPolicy* _collector_policy;
205 public:
206 ClearedAllSoftRefs(bool clear_all_soft_refs,
207 CollectorPolicy* collector_policy) :
208 _clear_all_soft_refs(clear_all_soft_refs),
209 _collector_policy(collector_policy) {}
210
211 ~ClearedAllSoftRefs() {
212 if (_clear_all_soft_refs) {
213 _collector_policy->cleared_all_soft_refs();
214 }
215 }
216 };
217
218 class GenCollectorPolicy : public CollectorPolicy {
219 friend class TestGenCollectorPolicy;
220 friend class VMStructs;
221 protected:
222 size_t _min_young_size;
223 size_t _initial_young_size;
224 size_t _max_young_size;
225 size_t _min_old_size;
226 size_t _initial_old_size;
227 size_t _max_old_size;
228
229 // _gen_alignment and _space_alignment will have the same value most of the
230 // time. When using large pages they can differ.
231 size_t _gen_alignment;
232
233 GenerationSpec* _young_gen_spec;
234 GenerationSpec* _old_gen_spec;
235
236 // Return true if an allocation should be attempted in the older generation
237 // if it fails in the younger generation. Return false, otherwise.
238 virtual bool should_try_older_generation_allocation(size_t word_size) const;
239
240 void initialize_flags();
241 void initialize_size_info();
242
243 DEBUG_ONLY(void assert_flags();)
244 DEBUG_ONLY(void assert_size_info();)
245
246 // Try to allocate space by expanding the heap.
247 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
248
249 // Compute max heap alignment.
250 size_t compute_max_alignment();
251
252 // Scale the base_size by NewRatio according to
253 // result = base_size / (NewRatio + 1)
254 // and align by min_alignment()
255 size_t scale_by_NewRatio_aligned(size_t base_size);
256
257 // Bound the value by the given maximum minus the min_alignment.
258 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size);
259
260 public:
261 GenCollectorPolicy();
262
263 // Accessors
264 size_t min_young_size() { return _min_young_size; }
265 size_t initial_young_size() { return _initial_young_size; }
266 size_t max_young_size() { return _max_young_size; }
267 size_t gen_alignment() { return _gen_alignment; }
268 size_t min_old_size() { return _min_old_size; }
269 size_t initial_old_size() { return _initial_old_size; }
270 size_t max_old_size() { return _max_old_size; }
271
272 int number_of_generations() { return 2; }
273
274 virtual GenerationSpec* young_gen_spec() const {
275 assert(_young_gen_spec != NULL, "Sanity check");
276 return _young_gen_spec;
277 }
278
279 virtual GenerationSpec* old_gen_spec() const {
280 assert(_old_gen_spec != NULL, "Sanity check");
281 return _old_gen_spec;
282 }
283
284 virtual GenCollectorPolicy* as_generation_policy() { return this; }
285
286 virtual void initialize_generations() { };
287
288 virtual void initialize_all() {
289 CollectorPolicy::initialize_all();
290 initialize_generations();
291 }
292
293 size_t young_gen_size_lower_bound();
294
295 HeapWord* mem_allocate_work(size_t size,
296 bool is_tlab,
297 bool* gc_overhead_limit_was_exceeded);
298
299 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
300
301 // Adaptive size policy
302 virtual void initialize_size_policy(size_t init_eden_size,
303 size_t init_promo_size,
304 size_t init_survivor_size);
305
306 virtual void post_heap_initialize() {
307 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info");
308 }
309
310 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
311
312 virtual CollectorPolicy::Name kind() {
313 return CollectorPolicy::GenCollectorPolicyKind;
314 }
315 };
316
317 class MarkSweepPolicy : public GenCollectorPolicy {
318 protected:
319 void initialize_alignments();
320 void initialize_generations();
321
322 public:
323 MarkSweepPolicy() {}
324
325 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
326
327 void initialize_gc_policy_counters();
328 };
329
330 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP