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 // Set to true by the GC if the just-completed gc cleared all 83 // softrefs. This is set to true whenever a gc clears all softrefs, and 84 // set to false each time gc returns to the mutator. For example, in the 85 // ParallelScavengeHeap case the latter would be done toward the end of 86 // mem_allocate() where it returns op.result() 87 bool _all_soft_refs_clear; 88 89 CollectorPolicy() : 90 _min_alignment(1), 91 _max_alignment(1), 92 _initial_heap_byte_size(0), 93 _max_heap_byte_size(0), 94 _min_heap_byte_size(0), 95 _size_policy(NULL), 96 _should_clear_all_soft_refs(false), 97 _all_soft_refs_clear(false) 98 {} 99 100 public: 101 // compute (conservative) maximum heap alignment 102 static size_t compute_max_alignment(); 103 104 void set_min_alignment(size_t align) { _min_alignment = align; } 105 size_t min_alignment() { return _min_alignment; } 106 void set_max_alignment(size_t align) { _max_alignment = align; } 107 size_t max_alignment() { return _max_alignment; } 108 109 size_t initial_heap_byte_size() { return _initial_heap_byte_size; } 110 void set_initial_heap_byte_size(size_t v) { _initial_heap_byte_size = v; } 111 size_t max_heap_byte_size() { return _max_heap_byte_size; } 112 void set_max_heap_byte_size(size_t v) { _max_heap_byte_size = v; } 113 size_t min_heap_byte_size() { return _min_heap_byte_size; } 114 void set_min_heap_byte_size(size_t v) { _min_heap_byte_size = v; } 115 116 enum Name { 117 CollectorPolicyKind, 118 TwoGenerationCollectorPolicyKind, 119 ConcurrentMarkSweepPolicyKind, 120 ASConcurrentMarkSweepPolicyKind, 121 G1CollectorPolicyKind 122 }; 123 124 AdaptiveSizePolicy* size_policy() { return _size_policy; } 125 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; } 126 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; } 127 // Returns the current value of _should_clear_all_soft_refs. 128 // _should_clear_all_soft_refs is set to false as a side effect. 129 bool use_should_clear_all_soft_refs(bool v); 130 bool all_soft_refs_clear() { return _all_soft_refs_clear; } 131 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; } 132 133 // Called by the GC after Soft Refs have been cleared to indicate 134 // that the request in _should_clear_all_soft_refs has been fulfilled. 135 void cleared_all_soft_refs(); 136 137 // Identification methods. 138 virtual GenCollectorPolicy* as_generation_policy() { return NULL; } 139 virtual TwoGenerationCollectorPolicy* as_two_generation_policy() { return NULL; } 140 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; } 141 #if INCLUDE_ALL_GCS 142 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; } 143 virtual G1CollectorPolicy* as_g1_policy() { return NULL; } 144 #endif // INCLUDE_ALL_GCS 145 // Note that these are not virtual. 146 bool is_generation_policy() { return as_generation_policy() != NULL; } 147 bool is_two_generation_policy() { return as_two_generation_policy() != NULL; } 148 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; } 149 #if INCLUDE_ALL_GCS 150 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; } 151 bool is_g1_policy() { return as_g1_policy() != NULL; } 152 #else // INCLUDE_ALL_GCS 153 bool is_concurrent_mark_sweep_policy() { return false; } 154 bool is_g1_policy() { return false; } 155 #endif // INCLUDE_ALL_GCS 156 157 158 virtual BarrierSet::Name barrier_set_name() = 0; 159 virtual GenRemSet::Name rem_set_name() = 0; 160 161 // Create the remembered set (to cover the given reserved region, 162 // allowing breaking up into at most "max_covered_regions"). 163 virtual GenRemSet* create_rem_set(MemRegion reserved, 164 int max_covered_regions); 165 166 // This method controls how a collector satisfies a request 167 // for a block of memory. "gc_time_limit_was_exceeded" will 168 // be set to true if the adaptive size policy determine that 169 // an excessive amount of time is being spent doing collections 170 // and caused a NULL to be returned. If a NULL is not returned, 171 // "gc_time_limit_was_exceeded" has an undefined meaning. 172 virtual HeapWord* mem_allocate_work(size_t size, 173 bool is_tlab, 174 bool* gc_overhead_limit_was_exceeded) = 0; 175 176 // This method controls how a collector handles one or more 177 // of its generations being fully allocated. 178 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0; 179 // This method controls how a collector handles a metadata allocation 180 // failure. 181 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 182 size_t size, 183 Metaspace::MetadataType mdtype); 184 185 // Performace Counter support 186 GCPolicyCounters* counters() { return _gc_policy_counters; } 187 188 // Create the jstat counters for the GC policy. By default, policy's 189 // don't have associated counters, and we complain if this is invoked. 190 virtual void initialize_gc_policy_counters() { 191 ShouldNotReachHere(); 192 } 193 194 virtual CollectorPolicy::Name kind() { 195 return CollectorPolicy::CollectorPolicyKind; 196 } 197 198 // Returns true if a collector has eden space with soft end. 199 virtual bool has_soft_ended_eden() { 200 return false; 201 } 202 203 }; 204 205 class ClearedAllSoftRefs : public StackObj { 206 bool _clear_all_soft_refs; 207 CollectorPolicy* _collector_policy; 208 public: 209 ClearedAllSoftRefs(bool clear_all_soft_refs, 210 CollectorPolicy* collector_policy) : 211 _clear_all_soft_refs(clear_all_soft_refs), 212 _collector_policy(collector_policy) {} 213 214 ~ClearedAllSoftRefs() { 215 if (_clear_all_soft_refs) { 216 _collector_policy->cleared_all_soft_refs(); 217 } 218 } 219 }; 220 221 class GenCollectorPolicy : public CollectorPolicy { 222 protected: 223 size_t _min_gen0_size; 224 size_t _initial_gen0_size; 225 size_t _max_gen0_size; 226 227 GenerationSpec **_generations; 228 229 // Return true if an allocation should be attempted in the older 230 // generation if it fails in the younger generation. Return 231 // false, otherwise. 232 virtual bool should_try_older_generation_allocation(size_t word_size) const; 233 234 void initialize_flags(); 235 void initialize_size_info(); 236 237 // Try to allocate space by expanding the heap. 238 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 239 240 // Scale the base_size by NewRation according to 241 // result = base_size / (NewRatio + 1) 242 // and align by min_alignment() 243 size_t scale_by_NewRatio_aligned(size_t base_size); 244 245 // Bound the value by the given maximum minus the 246 // min_alignment. 247 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 248 249 public: 250 // Accessors 251 size_t min_gen0_size() { return _min_gen0_size; } 252 void set_min_gen0_size(size_t v) { _min_gen0_size = v; } 253 size_t initial_gen0_size() { return _initial_gen0_size; } 254 void set_initial_gen0_size(size_t v) { _initial_gen0_size = v; } 255 size_t max_gen0_size() { return _max_gen0_size; } 256 void set_max_gen0_size(size_t v) { _max_gen0_size = v; } 257 258 virtual int number_of_generations() = 0; 259 260 virtual GenerationSpec **generations() { 261 assert(_generations != NULL, "Sanity check"); 262 return _generations; 263 } 264 265 virtual GenCollectorPolicy* as_generation_policy() { return this; } 266 267 virtual void initialize_generations() = 0; 268 269 virtual void initialize_all() { 270 initialize_flags(); 271 initialize_size_info(); 272 initialize_generations(); 273 } 274 275 HeapWord* mem_allocate_work(size_t size, 276 bool is_tlab, 277 bool* gc_overhead_limit_was_exceeded); 278 279 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab); 280 281 // Adaptive size policy 282 virtual void initialize_size_policy(size_t init_eden_size, 283 size_t init_promo_size, 284 size_t init_survivor_size); 285 }; 286 287 // All of hotspot's current collectors are subtypes of this 288 // class. Currently, these collectors all use the same gen[0], 289 // but have different gen[1] types. If we add another subtype 290 // of CollectorPolicy, this class should be broken out into 291 // its own file. 292 293 class TwoGenerationCollectorPolicy : public GenCollectorPolicy { 294 protected: 295 size_t _min_gen1_size; 296 size_t _initial_gen1_size; 297 size_t _max_gen1_size; 298 299 void initialize_flags(); 300 void initialize_size_info(); 301 void initialize_generations() { ShouldNotReachHere(); } 302 303 public: 304 // Accessors 305 size_t min_gen1_size() { return _min_gen1_size; } 306 void set_min_gen1_size(size_t v) { _min_gen1_size = v; } 307 size_t initial_gen1_size() { return _initial_gen1_size; } 308 void set_initial_gen1_size(size_t v) { _initial_gen1_size = v; } 309 size_t max_gen1_size() { return _max_gen1_size; } 310 void set_max_gen1_size(size_t v) { _max_gen1_size = v; } 311 312 // Inherited methods 313 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; } 314 315 int number_of_generations() { return 2; } 316 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; } 317 GenRemSet::Name rem_set_name() { return GenRemSet::CardTable; } 318 319 virtual CollectorPolicy::Name kind() { 320 return CollectorPolicy::TwoGenerationCollectorPolicyKind; 321 } 322 323 // Returns true is gen0 sizes were adjusted 324 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr, 325 const size_t heap_size, const size_t min_gen1_size); 326 }; 327 328 class MarkSweepPolicy : public TwoGenerationCollectorPolicy { 329 protected: 330 void initialize_generations(); 331 332 public: 333 MarkSweepPolicy(); 334 335 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 336 337 void initialize_gc_policy_counters(); 338 }; 339 340 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP