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 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 protected: 221 size_t _min_young_size; 222 size_t _initial_young_size; 223 size_t _max_young_size; 224 size_t _min_old_size; 225 size_t _initial_old_size; 226 size_t _max_old_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 generation 235 // if it fails in the younger generation. Return false, otherwise. 236 virtual bool should_try_older_generation_allocation(size_t word_size) const; 237 238 void initialize_flags(); 239 void initialize_size_info(); 240 241 DEBUG_ONLY(void assert_flags();) 242 DEBUG_ONLY(void assert_size_info();) 243 244 // Try to allocate space by expanding the heap. 245 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 246 247 // Compute max heap alignment. 248 size_t compute_max_alignment(); 249 250 // Scale the base_size by NewRatio according to 251 // result = base_size / (NewRatio + 1) 252 // and align by min_alignment() 253 size_t scale_by_NewRatio_aligned(size_t base_size); 254 255 // Bound the value by the given maximum minus the min_alignment. 256 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 257 258 public: 259 GenCollectorPolicy(); 260 261 // Accessors 262 size_t min_young_size() { return _min_young_size; } 263 size_t initial_young_size() { return _initial_young_size; } 264 size_t max_young_size() { return _max_young_size; } 265 size_t gen_alignment() { return _gen_alignment; } 266 size_t min_old_size() { return _min_old_size; } 267 size_t initial_old_size() { return _initial_old_size; } 268 size_t max_old_size() { return _max_old_size; } 269 270 int number_of_generations() { return 2; } 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_young_size == MaxNewSize, "Should be taken care of by initialize_size_info"); 301 } 302 303 BarrierSet::Name barrier_set_name() { return BarrierSet::CardTableModRef; } 304 305 virtual CollectorPolicy::Name kind() { 306 return CollectorPolicy::GenCollectorPolicyKind; 307 } 308 }; 309 310 class MarkSweepPolicy : public GenCollectorPolicy { 311 protected: 312 void initialize_alignments(); 313 void initialize_generations(); 314 315 public: 316 MarkSweepPolicy() {} 317 318 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 319 320 void initialize_gc_policy_counters(); 321 }; 322 323 #endif // SHARE_VM_MEMORY_COLLECTORPOLICY_HPP