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 #endif // INCLUDE_ALL_GCS 135 // Note that these are not virtual. 136 bool is_generation_policy() { return as_generation_policy() != NULL; } 137 bool is_mark_sweep_policy() { return as_mark_sweep_policy() != NULL; } 138 #if INCLUDE_ALL_GCS 139 bool is_concurrent_mark_sweep_policy() { return as_concurrent_mark_sweep_policy() != NULL; } 140 bool is_g1_policy() { return as_g1_policy() != NULL; } 141 #else // INCLUDE_ALL_GCS 142 bool is_concurrent_mark_sweep_policy() { return false; } 143 bool is_g1_policy() { return false; } 144 bool is_pgc_policy() { return false; } 145 #endif // INCLUDE_ALL_GCS 146 147 148 virtual GenRemSet* create_rem_set(MemRegion reserved); 149 150 // This method controls how a collector satisfies a request 151 // for a block of memory. "gc_time_limit_was_exceeded" will 152 // be set to true if the adaptive size policy determine that 153 // an excessive amount of time is being spent doing collections 154 // and caused a NULL to be returned. If a NULL is not returned, 155 // "gc_time_limit_was_exceeded" has an undefined meaning. 156 virtual HeapWord* mem_allocate_work(size_t size, 157 bool is_tlab, 158 bool* gc_overhead_limit_was_exceeded) = 0; 159 160 // This method controls how a collector handles one or more 161 // of its generations being fully allocated. 162 virtual HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab) = 0; 163 // This method controls how a collector handles a metadata allocation 164 // failure. 165 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data, 166 size_t size, 167 Metaspace::MetadataType mdtype); 168 169 // Performance Counter support 170 GCPolicyCounters* counters() { return _gc_policy_counters; } 171 172 // Create the jstat counters for the GC policy. By default, policy's 173 // don't have associated counters, and we complain if this is invoked. 174 virtual void initialize_gc_policy_counters() { 175 ShouldNotReachHere(); 176 } 177 178 // Do any updates required to global flags that are due to heap initialization 179 // changes 180 virtual void post_heap_initialize() = 0; 181 }; 182 183 class ClearedAllSoftRefs : public StackObj { 184 bool _clear_all_soft_refs; 185 CollectorPolicy* _collector_policy; 186 public: 187 ClearedAllSoftRefs(bool clear_all_soft_refs, 188 CollectorPolicy* collector_policy) : 189 _clear_all_soft_refs(clear_all_soft_refs), 190 _collector_policy(collector_policy) {} 191 192 ~ClearedAllSoftRefs() { 193 if (_clear_all_soft_refs) { 194 _collector_policy->cleared_all_soft_refs(); 195 } 196 } 197 }; 198 199 class GenCollectorPolicy : public CollectorPolicy { 200 friend class TestGenCollectorPolicy; 201 friend class VMStructs; 202 protected: 203 size_t _min_young_size; 204 size_t _initial_young_size; 205 size_t _max_young_size; 206 size_t _min_old_size; 207 size_t _initial_old_size; 208 size_t _max_old_size; 209 210 // _gen_alignment and _space_alignment will have the same value most of the 211 // time. When using large pages they can differ. 212 size_t _gen_alignment; 213 214 GenerationSpec* _young_gen_spec; 215 GenerationSpec* _old_gen_spec; 216 217 // Return true if an allocation should be attempted in the older generation 218 // if it fails in the younger generation. Return false, otherwise. 219 virtual bool should_try_older_generation_allocation(size_t word_size) const; 220 221 void initialize_flags(); 222 void initialize_size_info(); 223 224 DEBUG_ONLY(void assert_flags();) 225 DEBUG_ONLY(void assert_size_info();) 226 227 // Try to allocate space by expanding the heap. 228 virtual HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab); 229 230 // Compute max heap alignment. 231 size_t compute_max_alignment(); 232 233 // Scale the base_size by NewRatio according to 234 // result = base_size / (NewRatio + 1) 235 // and align by min_alignment() 236 size_t scale_by_NewRatio_aligned(size_t base_size); 237 238 // Bound the value by the given maximum minus the min_alignment. 239 size_t bound_minus_alignment(size_t desired_size, size_t maximum_size); 240 241 public: 242 GenCollectorPolicy(); 243 244 // Accessors 245 size_t min_young_size() { return _min_young_size; } 246 size_t initial_young_size() { return _initial_young_size; } 247 size_t max_young_size() { return _max_young_size; } 248 size_t gen_alignment() { return _gen_alignment; } 249 size_t min_old_size() { return _min_old_size; } 250 size_t initial_old_size() { return _initial_old_size; } 251 size_t max_old_size() { return _max_old_size; } 252 253 GenerationSpec* young_gen_spec() const { 254 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized"); 255 return _young_gen_spec; 256 } 257 258 GenerationSpec* old_gen_spec() const { 259 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized"); 260 return _old_gen_spec; 261 } 262 263 virtual GenCollectorPolicy* as_generation_policy() { return this; } 264 265 virtual void initialize_generations() { }; 266 267 virtual void initialize_all() { 268 CollectorPolicy::initialize_all(); 269 initialize_generations(); 270 } 271 272 size_t young_gen_size_lower_bound(); 273 274 size_t old_gen_size_lower_bound(); 275 276 HeapWord* mem_allocate_work(size_t size, 277 bool is_tlab, 278 bool* gc_overhead_limit_was_exceeded); 279 280 HeapWord *satisfy_failed_allocation(size_t size, bool is_tlab); 281 282 // Adaptive size policy 283 virtual void initialize_size_policy(size_t init_eden_size, 284 size_t init_promo_size, 285 size_t init_survivor_size); 286 287 virtual void post_heap_initialize() { 288 assert(_max_young_size == MaxNewSize, "Should be taken care of by initialize_size_info"); 289 } 290 }; 291 292 class MarkSweepPolicy : public GenCollectorPolicy { 293 protected: 294 void initialize_alignments(); 295 void initialize_generations(); 296 297 public: 298 MarkSweepPolicy() {} 299 300 MarkSweepPolicy* as_mark_sweep_policy() { return this; } 301 302 void initialize_gc_policy_counters(); 303 }; 304 305 #endif // SHARE_VM_GC_SHARED_COLLECTORPOLICY_HPP