1 /* 2 * Copyright (c) 2001, 2015, 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_GC_SHARED_COLLECTORPOLICY_HPP 26 #define SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP 27 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/genRemSet.hpp" 30 #include "gc/shared/generationSpec.hpp" 31 #include "memory/allocation.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 class ShenandoahCollectorPolicy; 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 DEBUG_ONLY(virtual void assert_flags();) 69 DEBUG_ONLY(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 is 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 AdaptiveSizePolicy* size_policy() { return _size_policy; } 116 bool should_clear_all_soft_refs() { return _should_clear_all_soft_refs; } 117 void set_should_clear_all_soft_refs(bool v) { _should_clear_all_soft_refs = v; } 118 // Returns the current value of _should_clear_all_soft_refs. 119 // _should_clear_all_soft_refs is set to false as a side effect. 120 bool use_should_clear_all_soft_refs(bool v); 121 bool all_soft_refs_clear() { return _all_soft_refs_clear; } 122 void set_all_soft_refs_clear(bool v) { _all_soft_refs_clear = v; } 123 124 // Called by the GC after Soft Refs have been cleared to indicate 125 // that the request in _should_clear_all_soft_refs has been fulfilled. 126 void cleared_all_soft_refs(); 127 128 // Identification methods. 129 virtual GenCollectorPolicy* as_generation_policy() { return NULL; } 130 virtual MarkSweepPolicy* as_mark_sweep_policy() { return NULL; } 131 #if INCLUDE_ALL_GCS 132 virtual ConcurrentMarkSweepPolicy* as_concurrent_mark_sweep_policy() { return NULL; } 133 virtual G1CollectorPolicy* as_g1_policy() { return NULL; } 134 virtual ShenandoahCollectorPolicy* as_pgc_policy() { return NULL; } 135 #endif // INCLUDE_ALL_GCS 136 // Note that these are not virtual. 137 bool is_generation_policy() { return as_generation_policy() != NULL; } 138 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; } 139 #if INCLUDE_ALL_GCS 140 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; } 141 bool is_g1_policy() { return as_g1_policy() != NULL; } 142 bool is_pgc_policy() { return as_pgc_policy() != NULL; } 143 #else // INCLUDE_ALL_GCS 144 bool is_concurrent_mark_sweep_policy() { return false; } 145 bool is_g1_policy() { return false; } 146 bool is_pgc_policy() { return false; } 147 #endif // INCLUDE_ALL_GCS 148 149 150 virtual GenRemSet* create_rem_set(MemRegion reserved); 151 152 // This method controls how a collector satisfies a request 153 // for a block of memory. "gc_time_limit_was_exceeded" will 154 // be set to true if the adaptive size policy determine that 155 // an excessive amount of time is being spent doing collections 156 // and caused a NULL to be returned. If a NULL is not returned, 157 // "gc_time_limit_was_exceeded" has an undefined meaning. 158 virtual HeapWord* mem_allocate_work(size_t size, 159 bool is_tlab, 160 bool* gc_overhead_limit_was_exceeded) = 0; 161 162 // This method controls how a collector handles one or more 163 // of its generations being fully allocated. 164 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0; 165 // This method controls how a collector handles a metadata allocation 166 // failure. 167 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 168 size_t size, 169 Metaspace::MetadataType mdtype); 170 171 // Performance Counter support 172 GCPolicyCounters* counters() { return _gc_policy_counters; } 173 174 // Create the jstat counters for the GC policy. By default, policy's 175 // don't have associated counters, and we complain if this is invoked. 176 virtual void initialize_gc_policy_counters() { 177 ShouldNotReachHere(); 178 } 179 180 // Do any updates required to global flags that are due to heap initialization 181 // changes 182 virtual void post_heap_initialize() = 0; 183 }; 184 185 class ClearedAllSoftRefs : public StackObj { 186 bool _clear_all_soft_refs; 187 CollectorPolicy* _collector_policy; 188 public: 189 ClearedAllSoftRefs(bool clear_all_soft_refs, 190 CollectorPolicy* collector_policy) : 191 _clear_all_soft_refs(clear_all_soft_refs), 192 _collector_policy(collector_policy) {} 193 194 ~ClearedAllSoftRefs() { 195 if (_clear_all_soft_refs) { 196 _collector_policy->cleared_all_soft_refs(); 197 } 198 } 199 }; 200 201 class GenCollectorPolicy : public CollectorPolicy { 202 friend class TestGenCollectorPolicy; 203 friend class VMStructs; 204 protected: 205 size_t _min_young_size; 206 size_t _initial_young_size; 207 size_t _max_young_size; 208 size_t _min_old_size; 209 size_t _initial_old_size; 210 size_t _max_old_size; 211 212 // _gen_alignment and _space_alignment will have the same value most of the 213 // time. When using large pages they can differ. 214 size_t _gen_alignment; 215 216 GenerationSpec* _young_gen_spec; 217 GenerationSpec* _old_gen_spec; 218 219 // Return true if an allocation should be attempted in the older generation 220 // if it fails in the younger generation. Return false, otherwise. 221 virtual bool should_try_older_generation_allocation(size_t word_size) const; 222 223 void initialize_flags(); 224 void initialize_size_info(); 225 226 DEBUG_ONLY(void assert_flags();) 227 DEBUG_ONLY(void assert_size_info();) 228 229 // Try to allocate space by expanding the heap. 230 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 231 232 // Compute max heap alignment. 233 size_t compute_max_alignment(); 234 235 // Scale the base_size by NewRatio 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 min_alignment. 241 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 242 243 public: 244 GenCollectorPolicy(); 245 246 // Accessors 247 size_t min_young_size() { return _min_young_size; } 248 size_t initial_young_size() { return _initial_young_size; } 249 size_t max_young_size() { return _max_young_size; } 250 size_t gen_alignment() { return _gen_alignment; } 251 size_t min_old_size() { return _min_old_size; } 252 size_t initial_old_size() { return _initial_old_size; } 253 size_t max_old_size() { return _max_old_size; } 254 255 GenerationSpec* young_gen_spec() const { 256 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized"); 257 return _young_gen_spec; 258 } 259 260 GenerationSpec* old_gen_spec() const { 261 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized"); 262 return _old_gen_spec; 263 } 264 265 virtual GenCollectorPolicy* as_generation_policy() { return this; } 266 267 virtual void initialize_generations() { }; 268 269 virtual void initialize_all() { 270 CollectorPolicy::initialize_all(); 271 initialize_generations(); 272 } 273 274 size_t young_gen_size_lower_bound(); 275 276 size_t old_gen_size_lower_bound(); 277 278 HeapWord* mem_allocate_work(size_t size, 279 bool is_tlab, 280 bool* gc_overhead_limit_was_exceeded); 281 282 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab); 283 284 // Adaptive size policy 285 virtual void initialize_size_policy(size_t init_eden_size, 286 size_t init_promo_size, 287 size_t init_survivor_size); 288 289 virtual void post_heap_initialize() { 290 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info"); 291 } 292 }; 293 294 class MarkSweepPolicy : public GenCollectorPolicy { 295 protected: 296 void initialize_alignments(); 297 void initialize_generations(); 298 299 public: 300 MarkSweepPolicy() {} 301 302 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 303 304 void initialize_gc_policy_counters(); 305 }; 306 307 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP