1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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 TwoGenerationCollectorPolicy;
51 class AdaptiveSizePolicy;
52 #if INCLUDE_ALL_GCS
53 class ConcurrentMarkSweepPolicy;
54 class G1CollectorPolicy;
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();
65 virtual void initialize_flags();
66 virtual void initialize_size_info();
67
68 virtual void assert_flags();
69 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 are 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 enum Name {
116 CollectorPolicyKind,
117 TwoGenerationCollectorPolicyKind,
118 ConcurrentMarkSweepPolicyKind,
119 ASConcurrentMarkSweepPolicyKind,
120 G1CollectorPolicyKind
121 };
122
123 AdaptiveSizePolicy* size_policy() { return _size_policy; }
124 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; }
125 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; }
126 // Returns the current value of _should_clear_all_soft_refs.
127 // _should_clear_all_soft_refs is set to false as a side effect.
128 bool use_should_clear_all_soft_refs(bool v);
129 bool all_soft_refs_clear() { return _all_soft_refs_clear; }
130 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; }
131
132 // Called by the GC after Soft Refs have been cleared to indicate
133 // that the request in _should_clear_all_soft_refs has been fulfilled.
134 void cleared_all_soft_refs();
135
136 // Identification methods.
137 virtual GenCollectorPolicy* as_generation_policy() { return NULL; }
138 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; }
139 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; }
140 #if INCLUDE_ALL_GCS
141 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; }
142 virtual G1CollectorPolicy* as_g1_policy() { return NULL; }
143 #endif // INCLUDE_ALL_GCS
144 // Note that these are not virtual.
145 bool is_generation_policy() { return as_generation_policy() != NULL; }
146 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; }
147 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; }
148 #if INCLUDE_ALL_GCS
149 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; }
150 bool is_g1_policy() { return as_g1_policy() != NULL; }
151 #else // INCLUDE_ALL_GCS
152 bool is_concurrent_mark_sweep_policy() { return false; }
153 bool is_g1_policy() { return false; }
154 #endif // INCLUDE_ALL_GCS
155
156
157 virtual BarrierSet::Name barrier_set_name() = 0;
158
159 // Create the remembered set (to cover the given reserved region,
160 // allowing breaking up into at most "max_covered_regions").
161 virtual GenRemSet* create_rem_set(MemRegion reserved,
162 int max_covered_regions);
163
164 // This method controls how a collector satisfies a request
165 // for a block of memory. "gc_time_limit_was_exceeded" will
166 // be set to true if the adaptive size policy determine that
167 // an excessive amount of time is being spent doing collections
168 // and caused a NULL to be returned. If a NULL is not returned,
169 // "gc_time_limit_was_exceeded" has an undefined meaning.
170 virtual HeapWord* mem_allocate_work(size_t size,
171 bool is_tlab,
172 bool* gc_overhead_limit_was_exceeded) = 0;
173
174 // This method controls how a collector handles one or more
175 // of its generations being fully allocated.
176 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0;
177 // This method controls how a collector handles a metadata allocation
178 // failure.
179 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
180 size_t size,
181 Metaspace::MetadataType mdtype);
182
183 // Performace Counter support
184 GCPolicyCounters* counters() { return _gc_policy_counters; }
185
186 // Create the jstat counters for the GC policy. By default, policy's
187 // don't have associated counters, and we complain if this is invoked.
188 virtual void initialize_gc_policy_counters() {
189 ShouldNotReachHere();
190 }
191
192 virtual CollectorPolicy::Name kind() {
193 return CollectorPolicy::CollectorPolicyKind;
194 }
195
196 // Returns true if a collector has eden space with soft end.
197 virtual bool has_soft_ended_eden() {
198 return false;
199 }
200
201 // Do any updates required to global flags that are due to heap initialization
202 // changes
203 virtual void post_heap_initialize() = 0;
204 };
205
206 class ClearedAllSoftRefs : public StackObj {
207 bool _clear_all_soft_refs;
208 CollectorPolicy* _collector_policy;
209 public:
210 ClearedAllSoftRefs(bool clear_all_soft_refs,
211 CollectorPolicy* collector_policy) :
212 _clear_all_soft_refs(clear_all_soft_refs),
213 _collector_policy(collector_policy) {}
214
215 ~ClearedAllSoftRefs() {
216 if (_clear_all_soft_refs) {
217 _collector_policy->cleared_all_soft_refs();
218 }
219 }
220 };
221
222 class GenCollectorPolicy : public CollectorPolicy {
223 protected:
224 size_t _min_gen0_size;
225 size_t _initial_gen0_size;
226 size_t _max_gen0_size;
227
228 // _gen_alignment and _space_alignment will have the same value most of the
229 // time. When using large pages they can differ.
230 size_t _gen_alignment;
231
232 GenerationSpec **_generations;
233
234 // Return true if an allocation should be attempted in the older
235 // generation if it fails in the younger generation. Return
236 // false, otherwise.
237 virtual bool should_try_older_generation_allocation(size_t word_size) const;
238
239 void initialize_alignments();
240 void initialize_flags();
241 void initialize_size_info();
242
243 void assert_flags();
244 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() : CollectorPolicy(), _min_gen0_size(0), _initial_gen0_size(0),
262 _max_gen0_size(0), _generations(NULL) {}
263
264 // Accessors
265 size_t min_gen0_size() { return _min_gen0_size; }
266 size_t initial_gen0_size() { return _initial_gen0_size; }
267 size_t max_gen0_size() { return _max_gen0_size; }
268 size_t gen_alignment() { return _gen_alignment; }
269
270 virtual int number_of_generations() = 0;
271
272 virtual GenerationSpec **generations() {
273 assert(_generations != NULL, "Sanity check");
274 return _generations;
275 }
276
277 virtual GenCollectorPolicy* as_generation_policy() { return this; }
278
279 virtual void initialize_generations() { };
280
281 virtual void initialize_all() {
282 CollectorPolicy::initialize_all();
283 initialize_generations();
284 }
285
286 size_t young_gen_size_lower_bound();
287
288 HeapWord* mem_allocate_work(size_t size,
289 bool is_tlab,
290 bool* gc_overhead_limit_was_exceeded);
291
292 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab);
293
294 // Adaptive size policy
295 virtual void initialize_size_policy(size_t init_eden_size,
296 size_t init_promo_size,
297 size_t init_survivor_size);
298
299 virtual void post_heap_initialize() {
300 assert(_max_gen0_size == MaxNewSize, "Should be taken care of by initialize_size_info");
301 }
302
303 // The alignment used for boundary between young gen and old gen
304 static size_t default_gen_alignment() {
305 return 64 * K * HeapWordSize;
306 }
307 };
308
309 // All of hotspot's current collectors are subtypes of this
310 // class. Currently, these collectors all use the same gen[0],
311 // but have different gen[1] types. If we add another subtype
312 // of CollectorPolicy, this class should be broken out into
313 // its own file.
314
315 class TwoGenerationCollectorPolicy : public GenCollectorPolicy {
316 protected:
317 size_t _min_gen1_size;
318 size_t _initial_gen1_size;
319 size_t _max_gen1_size;
320
321 void initialize_flags();
322 void initialize_size_info();
323
324 void assert_flags();
325 void assert_size_info();
326
327 public:
328 TwoGenerationCollectorPolicy() : GenCollectorPolicy(), _min_gen1_size(0),
329 _initial_gen1_size(0), _max_gen1_size(0) {}
330
331 // Accessors
332 size_t min_gen1_size() { return _min_gen1_size; }
333 size_t initial_gen1_size() { return _initial_gen1_size; }
334 size_t max_gen1_size() { return _max_gen1_size; }
335
336 // Inherited methods
337 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; }
338
339 int number_of_generations() { return 2; }
340 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; }
341
342 virtual CollectorPolicy::Name kind() {
343 return CollectorPolicy::TwoGenerationCollectorPolicyKind;
344 }
345
346 // Returns true is gen0 sizes were adjusted
347 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr,
348 const size_t heap_size, const size_t min_gen1_size);
349 };
350
351 class MarkSweepPolicy : public TwoGenerationCollectorPolicy {
352 protected:
353 void initialize_generations();
354
355 public:
356 MarkSweepPolicy() {}
357
358 MarkSweepPolicy* as_mark_sweep_policy() { return this; }
359
360 void initialize_gc_policy_counters();
361 };
362
363 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP