1 /* 2 * Copyright (c) 2001, 2013, 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_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 // Requires that the concrete subclass sets the alignment constraints 65 // before calling. 66 virtual void initialize_flags(); 67 virtual void initialize_size_info(); 68 69 size_t _initial_heap_byte_size; 70 size_t _max_heap_byte_size; 71 size_t _min_heap_byte_size; 72 73 size_t _min_alignment; 74 size_t _max_alignment; 75 76 // The sizing of the heap are controlled by a sizing policy. 77 AdaptiveSizePolicy* _size_policy; 78 79 // Set to true when policy wants soft refs cleared. 80 // Reset to false by gc after it clears all soft refs. 81 bool _should_clear_all_soft_refs; 82 83 // Set to true by the GC if the just-completed gc cleared all 84 // softrefs. This is set to true whenever a gc clears all softrefs, and 85 // set to false each time gc returns to the mutator. For example, in the 86 // ParallelScavengeHeap case the latter would be done toward the end of 87 // mem_allocate() where it returns op.result() 88 bool _all_soft_refs_clear; 89 90 CollectorPolicy() : 91 _min_alignment(1), 92 _max_alignment(1), 93 _initial_heap_byte_size(0), 94 _max_heap_byte_size(0), 95 _min_heap_byte_size(0), 96 _size_policy(NULL), 97 _should_clear_all_soft_refs(false), 98 _all_soft_refs_clear(false) 99 {} 100 101 public: 102 // Return maximum heap alignment that may be imposed by the policy 103 static size_t compute_max_alignment(); 104 105 size_t min_alignment() { return _min_alignment; } 106 size_t max_alignment() { return _max_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 enum Name { 113 CollectorPolicyKind, 114 TwoGenerationCollectorPolicyKind, 115 ConcurrentMarkSweepPolicyKind, 116 ASConcurrentMarkSweepPolicyKind, 117 G1CollectorPolicyKind 118 }; 119 120 AdaptiveSizePolicy* size_policy() { return _size_policy; } 121 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; } 122 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; } 123 // Returns the current value of _should_clear_all_soft_refs. 124 // _should_clear_all_soft_refs is set to false as a side effect. 125 bool use_should_clear_all_soft_refs(bool v); 126 bool all_soft_refs_clear() { return _all_soft_refs_clear; } 127 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; } 128 129 // Called by the GC after Soft Refs have been cleared to indicate 130 // that the request in _should_clear_all_soft_refs has been fulfilled. 131 void cleared_all_soft_refs(); 132 133 // Identification methods. 134 virtual GenCollectorPolicy* as_generation_policy() { return NULL; } 135 virtual TwoGenerationCollectorPolicy* as_two_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_two_generation_policy() { return as_two_generation_policy() != NULL; } 144 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; } 145 #if INCLUDE_ALL_GCS 146 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; } 147 bool is_g1_policy() { return as_g1_policy() != NULL; } 148 #else // INCLUDE_ALL_GCS 149 bool is_concurrent_mark_sweep_policy() { return false; } 150 bool is_g1_policy() { return false; } 151 #endif // INCLUDE_ALL_GCS 152 153 154 virtual BarrierSet::Name barrier_set_name() = 0; 155 156 // Create the remembered set (to cover the given reserved region, 157 // allowing breaking up into at most "max_covered_regions"). 158 virtual GenRemSet* create_rem_set(MemRegion reserved, 159 int max_covered_regions); 160 161 // This method controls how a collector satisfies a request 162 // for a block of memory. "gc_time_limit_was_exceeded" will 163 // be set to true if the adaptive size policy determine that 164 // an excessive amount of time is being spent doing collections 165 // and caused a NULL to be returned. If a NULL is not returned, 166 // "gc_time_limit_was_exceeded" has an undefined meaning. 167 virtual HeapWord* mem_allocate_work(size_t size, 168 bool is_tlab, 169 bool* gc_overhead_limit_was_exceeded) = 0; 170 171 // This method controls how a collector handles one or more 172 // of its generations being fully allocated. 173 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0; 174 // This method controls how a collector handles a metadata allocation 175 // failure. 176 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 177 size_t size, 178 Metaspace::MetadataType mdtype); 179 180 // Performace Counter support 181 GCPolicyCounters* counters() { return _gc_policy_counters; } 182 183 // Create the jstat counters for the GC policy. By default, policy's 184 // don't have associated counters, and we complain if this is invoked. 185 virtual void initialize_gc_policy_counters() { 186 ShouldNotReachHere(); 187 } 188 189 virtual CollectorPolicy::Name kind() { 190 return CollectorPolicy::CollectorPolicyKind; 191 } 192 193 // Returns true if a collector has eden space with soft end. 194 virtual bool has_soft_ended_eden() { 195 return false; 196 } 197 198 }; 199 200 class ClearedAllSoftRefs : public StackObj { 201 bool _clear_all_soft_refs; 202 CollectorPolicy* _collector_policy; 203 public: 204 ClearedAllSoftRefs(bool clear_all_soft_refs, 205 CollectorPolicy* collector_policy) : 206 _clear_all_soft_refs(clear_all_soft_refs), 207 _collector_policy(collector_policy) {} 208 209 ~ClearedAllSoftRefs() { 210 if (_clear_all_soft_refs) { 211 _collector_policy->cleared_all_soft_refs(); 212 } 213 } 214 }; 215 216 class GenCollectorPolicy : public CollectorPolicy { 217 protected: 218 size_t _min_gen0_size; 219 size_t _initial_gen0_size; 220 size_t _max_gen0_size; 221 222 GenerationSpec **_generations; 223 224 // Return true if an allocation should be attempted in the older 225 // generation if it fails in the younger generation. Return 226 // false, otherwise. 227 virtual bool should_try_older_generation_allocation(size_t word_size) const; 228 229 void initialize_flags(); 230 void initialize_size_info(); 231 232 // Try to allocate space by expanding the heap. 233 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 234 235 // Scale the base_size by NewRation according to 236 // result = base_size / (NewRatio + 1) 237 // and align by min_alignment() 238 size_t scale_by_NewRatio_aligned(size_t base_size); 239 240 // Bound the value by the given maximum minus the 241 // min_alignment. 242 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 243 244 public: 245 // Accessors 246 size_t min_gen0_size() { return _min_gen0_size; } 247 size_t initial_gen0_size() { return _initial_gen0_size; } 248 size_t max_gen0_size() { return _max_gen0_size; } 249 250 virtual int number_of_generations() = 0; 251 252 virtual GenerationSpec **generations() { 253 assert(_generations != NULL, "Sanity check"); 254 return _generations; 255 } 256 257 virtual GenCollectorPolicy* as_generation_policy() { return this; } 258 259 virtual void initialize_generations() = 0; 260 261 virtual void initialize_all() { 262 initialize_flags(); 263 initialize_size_info(); 264 initialize_generations(); 265 } 266 267 HeapWord* mem_allocate_work(size_t size, 268 bool is_tlab, 269 bool* gc_overhead_limit_was_exceeded); 270 271 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab); 272 273 // Adaptive size policy 274 virtual void initialize_size_policy(size_t init_eden_size, 275 size_t init_promo_size, 276 size_t init_survivor_size); 277 278 // The alignment used for eden and survivors within the young gen 279 // and for boundary between young gen and old gen. 280 static size_t intra_heap_alignment() { 281 return 64 * K * HeapWordSize; 282 } 283 }; 284 285 // All of hotspot's current collectors are subtypes of this 286 // class. Currently, these collectors all use the same gen[0], 287 // but have different gen[1] types. If we add another subtype 288 // of CollectorPolicy, this class should be broken out into 289 // its own file. 290 291 class TwoGenerationCollectorPolicy : public GenCollectorPolicy { 292 protected: 293 size_t _min_gen1_size; 294 size_t _initial_gen1_size; 295 size_t _max_gen1_size; 296 297 void initialize_flags(); 298 void initialize_size_info(); 299 void initialize_generations() { ShouldNotReachHere(); } 300 301 public: 302 // Accessors 303 size_t min_gen1_size() { return _min_gen1_size; } 304 size_t initial_gen1_size() { return _initial_gen1_size; } 305 size_t max_gen1_size() { return _max_gen1_size; } 306 307 // Inherited methods 308 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; } 309 310 int number_of_generations() { return 2; } 311 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; } 312 313 virtual CollectorPolicy::Name kind() { 314 return CollectorPolicy::TwoGenerationCollectorPolicyKind; 315 } 316 317 // Returns true is gen0 sizes were adjusted 318 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr, 319 const size_t heap_size, const size_t min_gen1_size); 320 }; 321 322 class MarkSweepPolicy : public TwoGenerationCollectorPolicy { 323 protected: 324 void initialize_generations(); 325 326 public: 327 MarkSweepPolicy(); 328 329 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 330 331 void initialize_gc_policy_counters(); 332 }; 333 334 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP