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 virtual void initialize_alignments() = 0; 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_flags(); 240 void initialize_size_info(); 241 242 void assert_flags(); 243 void assert_size_info(); 244 245 // Try to allocate space by expanding the heap. 246 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 247 248 // Compute max heap alignment 249 size_t compute_max_alignment(); 250 251 // Scale the base_size by NewRatio according to 252 // result = base_size / (NewRatio + 1) 253 // and align by min_alignment() 254 size_t scale_by_NewRatio_aligned(size_t base_size); 255 256 // Bound the value by the given maximum minus the min_alignment 257 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 258 259 public: 260 GenCollectorPolicy() : CollectorPolicy(), _min_gen0_size(0), _initial_gen0_size(0), 261 _max_gen0_size(0), _generations(NULL) {} 262 263 // Accessors 264 size_t min_gen0_size() { return _min_gen0_size; } 265 size_t initial_gen0_size() { return _initial_gen0_size; } 266 size_t max_gen0_size() { return _max_gen0_size; } 267 size_t gen_alignment() { return _gen_alignment; } 268 269 virtual int number_of_generations() = 0; 270 271 virtual GenerationSpec **generations() { 272 assert(_generations != NULL, "Sanity check"); 273 return _generations; 274 } 275 276 virtual GenCollectorPolicy* as_generation_policy() { return this; } 277 278 virtual void initialize_generations() { }; 279 280 virtual void initialize_all() { 281 CollectorPolicy::initialize_all(); 282 initialize_generations(); 283 } 284 285 size_t young_gen_size_lower_bound(); 286 287 HeapWord* mem_allocate_work(size_t size, 288 bool is_tlab, 289 bool* gc_overhead_limit_was_exceeded); 290 291 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab); 292 293 // Adaptive size policy 294 virtual void initialize_size_policy(size_t init_eden_size, 295 size_t init_promo_size, 296 size_t init_survivor_size); 297 298 virtual void post_heap_initialize() { 299 assert(_max_gen0_size == MaxNewSize, "Should be taken care of by initialize_size_info"); 300 } 301 }; 302 303 // All of hotspot's current collectors are subtypes of this 304 // class. Currently, these collectors all use the same gen[0], 305 // but have different gen[1] types. If we add another subtype 306 // of CollectorPolicy, this class should be broken out into 307 // its own file. 308 309 class TwoGenerationCollectorPolicy : public GenCollectorPolicy { 310 protected: 311 size_t _min_gen1_size; 312 size_t _initial_gen1_size; 313 size_t _max_gen1_size; 314 315 void initialize_flags(); 316 void initialize_size_info(); 317 318 void assert_flags(); 319 void assert_size_info(); 320 321 public: 322 TwoGenerationCollectorPolicy() : GenCollectorPolicy(), _min_gen1_size(0), 323 _initial_gen1_size(0), _max_gen1_size(0) {} 324 325 // Accessors 326 size_t min_gen1_size() { return _min_gen1_size; } 327 size_t initial_gen1_size() { return _initial_gen1_size; } 328 size_t max_gen1_size() { return _max_gen1_size; } 329 330 // Inherited methods 331 TwoGenerationCollectorPolicy* as_two_generation_policy() { return this; } 332 333 int number_of_generations() { return 2; } 334 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; } 335 336 virtual CollectorPolicy::Name kind() { 337 return CollectorPolicy::TwoGenerationCollectorPolicyKind; 338 } 339 340 // Returns true is gen0 sizes were adjusted 341 bool adjust_gen0_sizes(size_t* gen0_size_ptr, size_t* gen1_size_ptr, 342 const size_t heap_size, const size_t min_gen1_size); 343 }; 344 345 class MarkSweepPolicy : public TwoGenerationCollectorPolicy { 346 protected: 347 void initialize_alignments(); 348 void initialize_generations(); 349 350 public: 351 MarkSweepPolicy() {} 352 353 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 354 355 void initialize_gc_policy_counters(); 356 }; 357 358 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP