1 /* 2 * Copyright (c) 2004, 2018, 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_ADAPTIVESIZEPOLICY_HPP 26 #define SHARE_VM_GC_SHARED_ADAPTIVESIZEPOLICY_HPP 27 28 #include "gc/shared/gcCause.hpp" 29 #include "gc/shared/gcOverheadChecker.hpp" 30 #include "gc/shared/gcUtil.hpp" 31 #include "memory/allocation.hpp" 32 33 // This class keeps statistical information and computes the 34 // size of the heap. 35 36 // Forward decls 37 class elapsedTimer; 38 39 class AdaptiveSizePolicy : public CHeapObj<mtGC> { 40 friend class GCAdaptivePolicyCounters; 41 friend class PSGCAdaptivePolicyCounters; 42 friend class CMSGCAdaptivePolicyCounters; 43 protected: 44 45 enum GCPolicyKind { 46 _gc_adaptive_size_policy, 47 _gc_ps_adaptive_size_policy, 48 _gc_cms_adaptive_size_policy 49 }; 50 virtual GCPolicyKind kind() const { return _gc_adaptive_size_policy; } 51 52 enum SizePolicyTrueValues { 53 decrease_old_gen_for_throughput_true = -7, 54 decrease_young_gen_for_througput_true = -6, 55 56 increase_old_gen_for_min_pauses_true = -5, 57 decrease_old_gen_for_min_pauses_true = -4, 58 decrease_young_gen_for_maj_pauses_true = -3, 59 increase_young_gen_for_min_pauses_true = -2, 60 increase_old_gen_for_maj_pauses_true = -1, 61 62 decrease_young_gen_for_min_pauses_true = 1, 63 decrease_old_gen_for_maj_pauses_true = 2, 64 increase_young_gen_for_maj_pauses_true = 3, 65 66 increase_old_gen_for_throughput_true = 4, 67 increase_young_gen_for_througput_true = 5, 68 69 decrease_young_gen_for_footprint_true = 6, 70 decrease_old_gen_for_footprint_true = 7, 71 decide_at_full_gc_true = 8 72 }; 73 74 // Goal for the fraction of the total time during which application 75 // threads run 76 const double _throughput_goal; 77 78 // Last calculated sizes, in bytes, and aligned 79 size_t _eden_size; // calculated eden free space in bytes 80 size_t _promo_size; // calculated cms gen free space in bytes 81 82 size_t _survivor_size; // calculated survivor size in bytes 83 84 // Support for UseGCOverheadLimit 85 GCOverheadChecker _overhead_checker; 86 87 // Minor collection timers used to determine both 88 // pause and interval times for collections 89 static elapsedTimer _minor_timer; 90 91 // Major collection timers, used to determine both 92 // pause and interval times for collections 93 static elapsedTimer _major_timer; 94 95 // Time statistics 96 AdaptivePaddedAverage* _avg_minor_pause; 97 AdaptiveWeightedAverage* _avg_minor_interval; 98 AdaptiveWeightedAverage* _avg_minor_gc_cost; 99 100 AdaptiveWeightedAverage* _avg_major_interval; 101 AdaptiveWeightedAverage* _avg_major_gc_cost; 102 103 // Footprint statistics 104 AdaptiveWeightedAverage* _avg_young_live; 105 AdaptiveWeightedAverage* _avg_eden_live; 106 AdaptiveWeightedAverage* _avg_old_live; 107 108 // Statistics for survivor space calculation for young generation 109 AdaptivePaddedAverage* _avg_survived; 110 111 // Objects that have been directly allocated in the old generation 112 AdaptivePaddedNoZeroDevAverage* _avg_pretenured; 113 114 // Variable for estimating the major and minor pause times. 115 // These variables represent linear least-squares fits of 116 // the data. 117 // minor pause time vs. old gen size 118 LinearLeastSquareFit* _minor_pause_old_estimator; 119 // minor pause time vs. young gen size 120 LinearLeastSquareFit* _minor_pause_young_estimator; 121 122 // Variables for estimating the major and minor collection costs 123 // minor collection time vs. young gen size 124 LinearLeastSquareFit* _minor_collection_estimator; 125 // major collection time vs. cms gen size 126 LinearLeastSquareFit* _major_collection_estimator; 127 128 // These record the most recent collection times. They 129 // are available as an alternative to using the averages 130 // for making ergonomic decisions. 131 double _latest_minor_mutator_interval_seconds; 132 133 // Allowed difference between major and minor GC times, used 134 // for computing tenuring_threshold 135 const double _threshold_tolerance_percent; 136 137 const double _gc_pause_goal_sec; // Goal for maximum GC pause 138 139 // Flag indicating that the adaptive policy is ready to use 140 bool _young_gen_policy_is_ready; 141 142 // Decrease/increase the young generation for minor pause time 143 int _change_young_gen_for_min_pauses; 144 145 // Decrease/increase the old generation for major pause time 146 int _change_old_gen_for_maj_pauses; 147 148 // change old generation for throughput 149 int _change_old_gen_for_throughput; 150 151 // change young generation for throughput 152 int _change_young_gen_for_throughput; 153 154 // Flag indicating that the policy would 155 // increase the tenuring threshold because of the total major GC cost 156 // is greater than the total minor GC cost 157 bool _increment_tenuring_threshold_for_gc_cost; 158 // decrease the tenuring threshold because of the the total minor GC 159 // cost is greater than the total major GC cost 160 bool _decrement_tenuring_threshold_for_gc_cost; 161 // decrease due to survivor size limit 162 bool _decrement_tenuring_threshold_for_survivor_limit; 163 164 // decrease generation sizes for footprint 165 int _decrease_for_footprint; 166 167 // Set if the ergonomic decisions were made at a full GC. 168 int _decide_at_full_gc; 169 170 // Changing the generation sizing depends on the data that is 171 // gathered about the effects of changes on the pause times and 172 // throughput. These variable count the number of data points 173 // gathered. The policy may use these counters as a threshold 174 // for reliable data. 175 julong _young_gen_change_for_minor_throughput; 176 julong _old_gen_change_for_major_throughput; 177 178 // Accessors 179 180 double gc_pause_goal_sec() const { return _gc_pause_goal_sec; } 181 // The value returned is unitless: it's the proportion of time 182 // spent in a particular collection type. 183 // An interval time will be 0.0 if a collection type hasn't occurred yet. 184 // The 1.4.2 implementation put a floor on the values of major_gc_cost 185 // and minor_gc_cost. This was useful because of the way major_gc_cost 186 // and minor_gc_cost was used in calculating the sizes of the generations. 187 // Do not use a floor in this implementation because any finite value 188 // will put a limit on the throughput that can be achieved and any 189 // throughput goal above that limit will drive the generations sizes 190 // to extremes. 191 double major_gc_cost() const { 192 return MAX2(0.0F, _avg_major_gc_cost->average()); 193 } 194 195 // The value returned is unitless: it's the proportion of time 196 // spent in a particular collection type. 197 // An interval time will be 0.0 if a collection type hasn't occurred yet. 198 // The 1.4.2 implementation put a floor on the values of major_gc_cost 199 // and minor_gc_cost. This was useful because of the way major_gc_cost 200 // and minor_gc_cost was used in calculating the sizes of the generations. 201 // Do not use a floor in this implementation because any finite value 202 // will put a limit on the throughput that can be achieved and any 203 // throughput goal above that limit will drive the generations sizes 204 // to extremes. 205 206 double minor_gc_cost() const { 207 return MAX2(0.0F, _avg_minor_gc_cost->average()); 208 } 209 210 // Because we're dealing with averages, gc_cost() can be 211 // larger than 1.0 if just the sum of the minor cost the 212 // the major cost is used. Worse than that is the 213 // fact that the minor cost and the major cost each 214 // tend toward 1.0 in the extreme of high GC costs. 215 // Limit the value of gc_cost to 1.0 so that the mutator 216 // cost stays non-negative. 217 virtual double gc_cost() const { 218 double result = MIN2(1.0, minor_gc_cost() + major_gc_cost()); 219 assert(result >= 0.0, "Both minor and major costs are non-negative"); 220 return result; 221 } 222 223 // Elapsed time since the last major collection. 224 virtual double time_since_major_gc() const; 225 226 // Average interval between major collections to be used 227 // in calculating the decaying major GC cost. An overestimate 228 // of this time would be a conservative estimate because 229 // this time is used to decide if the major GC cost 230 // should be decayed (i.e., if the time since the last 231 // major GC is long compared to the time returned here, 232 // then the major GC cost will be decayed). See the 233 // implementations for the specifics. 234 virtual double major_gc_interval_average_for_decay() const { 235 return _avg_major_interval->average(); 236 } 237 238 // Return the cost of the GC where the major GC cost 239 // has been decayed based on the time since the last 240 // major collection. 241 double decaying_gc_cost() const; 242 243 // Decay the major GC cost. Use this only for decisions on 244 // whether to adjust, not to determine by how much to adjust. 245 // This approximation is crude and may not be good enough for the 246 // latter. 247 double decaying_major_gc_cost() const; 248 249 // Return the mutator cost using the decayed 250 // GC cost. 251 double adjusted_mutator_cost() const { 252 double result = 1.0 - decaying_gc_cost(); 253 assert(result >= 0.0, "adjusted mutator cost calculation is incorrect"); 254 return result; 255 } 256 257 virtual double mutator_cost() const { 258 double result = 1.0 - gc_cost(); 259 assert(result >= 0.0, "mutator cost calculation is incorrect"); 260 return result; 261 } 262 263 264 bool young_gen_policy_is_ready() { return _young_gen_policy_is_ready; } 265 266 void update_minor_pause_young_estimator(double minor_pause_in_ms); 267 virtual void update_minor_pause_old_estimator(double minor_pause_in_ms) { 268 // This is not meaningful for all policies but needs to be present 269 // to use minor_collection_end() in its current form. 270 } 271 272 virtual size_t eden_increment(size_t cur_eden); 273 virtual size_t eden_increment(size_t cur_eden, uint percent_change); 274 virtual size_t eden_decrement(size_t cur_eden); 275 virtual size_t promo_increment(size_t cur_eden); 276 virtual size_t promo_increment(size_t cur_eden, uint percent_change); 277 virtual size_t promo_decrement(size_t cur_eden); 278 279 virtual void clear_generation_free_space_flags(); 280 281 int change_old_gen_for_throughput() const { 282 return _change_old_gen_for_throughput; 283 } 284 void set_change_old_gen_for_throughput(int v) { 285 _change_old_gen_for_throughput = v; 286 } 287 int change_young_gen_for_throughput() const { 288 return _change_young_gen_for_throughput; 289 } 290 void set_change_young_gen_for_throughput(int v) { 291 _change_young_gen_for_throughput = v; 292 } 293 294 int change_old_gen_for_maj_pauses() const { 295 return _change_old_gen_for_maj_pauses; 296 } 297 void set_change_old_gen_for_maj_pauses(int v) { 298 _change_old_gen_for_maj_pauses = v; 299 } 300 301 bool decrement_tenuring_threshold_for_gc_cost() const { 302 return _decrement_tenuring_threshold_for_gc_cost; 303 } 304 void set_decrement_tenuring_threshold_for_gc_cost(bool v) { 305 _decrement_tenuring_threshold_for_gc_cost = v; 306 } 307 bool increment_tenuring_threshold_for_gc_cost() const { 308 return _increment_tenuring_threshold_for_gc_cost; 309 } 310 void set_increment_tenuring_threshold_for_gc_cost(bool v) { 311 _increment_tenuring_threshold_for_gc_cost = v; 312 } 313 bool decrement_tenuring_threshold_for_survivor_limit() const { 314 return _decrement_tenuring_threshold_for_survivor_limit; 315 } 316 void set_decrement_tenuring_threshold_for_survivor_limit(bool v) { 317 _decrement_tenuring_threshold_for_survivor_limit = v; 318 } 319 // Return true if the policy suggested a change. 320 bool tenuring_threshold_change() const; 321 322 public: 323 AdaptiveSizePolicy(size_t init_eden_size, 324 size_t init_promo_size, 325 size_t init_survivor_size, 326 double gc_pause_goal_sec, 327 uint gc_cost_ratio); 328 329 bool is_gc_cms_adaptive_size_policy() { 330 return kind() == _gc_cms_adaptive_size_policy; 331 } 332 bool is_gc_ps_adaptive_size_policy() { 333 return kind() == _gc_ps_adaptive_size_policy; 334 } 335 336 AdaptivePaddedAverage* avg_minor_pause() const { return _avg_minor_pause; } 337 AdaptiveWeightedAverage* avg_minor_interval() const { 338 return _avg_minor_interval; 339 } 340 AdaptiveWeightedAverage* avg_minor_gc_cost() const { 341 return _avg_minor_gc_cost; 342 } 343 344 AdaptiveWeightedAverage* avg_major_gc_cost() const { 345 return _avg_major_gc_cost; 346 } 347 348 AdaptiveWeightedAverage* avg_young_live() const { return _avg_young_live; } 349 AdaptiveWeightedAverage* avg_eden_live() const { return _avg_eden_live; } 350 AdaptiveWeightedAverage* avg_old_live() const { return _avg_old_live; } 351 352 AdaptivePaddedAverage* avg_survived() const { return _avg_survived; } 353 AdaptivePaddedNoZeroDevAverage* avg_pretenured() { return _avg_pretenured; } 354 355 // Methods indicating events of interest to the adaptive size policy, 356 // called by GC algorithms. It is the responsibility of users of this 357 // policy to call these methods at the correct times! 358 virtual void minor_collection_begin(); 359 virtual void minor_collection_end(GCCause::Cause gc_cause); 360 virtual LinearLeastSquareFit* minor_pause_old_estimator() const { 361 return _minor_pause_old_estimator; 362 } 363 364 LinearLeastSquareFit* minor_pause_young_estimator() { 365 return _minor_pause_young_estimator; 366 } 367 LinearLeastSquareFit* minor_collection_estimator() { 368 return _minor_collection_estimator; 369 } 370 371 LinearLeastSquareFit* major_collection_estimator() { 372 return _major_collection_estimator; 373 } 374 375 float minor_pause_young_slope() { 376 return _minor_pause_young_estimator->slope(); 377 } 378 379 float minor_collection_slope() { return _minor_collection_estimator->slope();} 380 float major_collection_slope() { return _major_collection_estimator->slope();} 381 382 float minor_pause_old_slope() { 383 return _minor_pause_old_estimator->slope(); 384 } 385 386 void set_eden_size(size_t new_size) { 387 _eden_size = new_size; 388 } 389 void set_survivor_size(size_t new_size) { 390 _survivor_size = new_size; 391 } 392 393 size_t calculated_eden_size_in_bytes() const { 394 return _eden_size; 395 } 396 397 size_t calculated_promo_size_in_bytes() const { 398 return _promo_size; 399 } 400 401 size_t calculated_survivor_size_in_bytes() const { 402 return _survivor_size; 403 } 404 405 bool gc_overhead_limit_exceeded() { 406 return _overhead_checker.gc_overhead_limit_exceeded(); 407 } 408 void set_gc_overhead_limit_exceeded(bool v) { 409 _overhead_checker.set_gc_overhead_limit_exceeded(v); 410 } 411 412 bool gc_overhead_limit_near() { 413 return _overhead_checker.gc_overhead_limit_near(); 414 } 415 416 void reset_gc_overhead_limit_count() { 417 _overhead_checker.reset_gc_overhead_limit_count(); 418 } 419 // accessors for flags recording the decisions to resize the 420 // generations to meet the pause goal. 421 422 int change_young_gen_for_min_pauses() const { 423 return _change_young_gen_for_min_pauses; 424 } 425 void set_change_young_gen_for_min_pauses(int v) { 426 _change_young_gen_for_min_pauses = v; 427 } 428 void set_decrease_for_footprint(int v) { _decrease_for_footprint = v; } 429 int decrease_for_footprint() const { return _decrease_for_footprint; } 430 int decide_at_full_gc() { return _decide_at_full_gc; } 431 void set_decide_at_full_gc(int v) { _decide_at_full_gc = v; } 432 433 // Check the conditions for an out-of-memory due to excessive GC time. 434 // Set _gc_overhead_limit_exceeded if all the conditions have been met. 435 void check_gc_overhead_limit(size_t eden_live, 436 size_t max_old_gen_size, 437 size_t max_eden_size, 438 bool is_full_gc, 439 GCCause::Cause gc_cause, 440 SoftRefPolicy* soft_ref_policy); 441 442 static bool should_update_promo_stats(GCCause::Cause cause) { 443 return ((GCCause::is_user_requested_gc(cause) && 444 UseAdaptiveSizePolicyWithSystemGC) || 445 GCCause::is_tenured_allocation_failure_gc(cause)); 446 } 447 448 static bool should_update_eden_stats(GCCause::Cause cause) { 449 return ((GCCause::is_user_requested_gc(cause) && 450 UseAdaptiveSizePolicyWithSystemGC) || 451 GCCause::is_allocation_failure_gc(cause)); 452 } 453 454 // Printing support 455 virtual bool print() const; 456 void print_tenuring_threshold(uint new_tenuring_threshold) const; 457 }; 458 459 #endif // SHARE_VM_GC_SHARED_ADAPTIVESIZEPOLICY_HPP