1 /* 2 * Copyright (c) 2002, 2020, 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_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP 26 #define SHARE_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP 27 28 #include "gc/shared/adaptiveSizePolicy.hpp" 29 #include "gc/shared/gcCause.hpp" 30 #include "gc/shared/gcStats.hpp" 31 #include "gc/shared/gcUtil.hpp" 32 #include "utilities/align.hpp" 33 34 // This class keeps statistical information and computes the 35 // optimal free space for both the young and old generation 36 // based on current application characteristics (based on gc cost 37 // and application footprint). 38 // 39 // It also computes an optimal tenuring threshold between the young 40 // and old generations, so as to equalize the cost of collections 41 // of those generations, as well as optimal survivor space sizes 42 // for the young generation. 43 // 44 // While this class is specifically intended for a generational system 45 // consisting of a young gen (containing an Eden and two semi-spaces) 46 // and a tenured gen, as well as a perm gen for reflective data, it 47 // makes NO references to specific generations. 48 // 49 // 05/02/2003 Update 50 // The 1.5 policy makes use of data gathered for the costs of GC on 51 // specific generations. That data does reference specific 52 // generation. Also diagnostics specific to generations have 53 // been added. 54 55 // Forward decls 56 class elapsedTimer; 57 58 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy { 59 friend class PSGCAdaptivePolicyCounters; 60 private: 61 // These values are used to record decisions made during the 62 // policy. For example, if the young generation was decreased 63 // to decrease the GC cost of minor collections the value 64 // decrease_young_gen_for_throughput_true is used. 65 66 // Last calculated sizes, in bytes, and aligned 67 // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's 68 69 // Time statistics 70 AdaptivePaddedAverage* _avg_major_pause; 71 72 // Footprint statistics 73 AdaptiveWeightedAverage* _avg_base_footprint; 74 75 // Statistical data gathered for GC 76 GCStats _gc_stats; 77 78 const double _collection_cost_margin_fraction; 79 80 // Variable for estimating the major and minor pause times. 81 // These variables represent linear least-squares fits of 82 // the data. 83 // major pause time vs. old gen size 84 LinearLeastSquareFit* _major_pause_old_estimator; 85 // major pause time vs. young gen size 86 LinearLeastSquareFit* _major_pause_young_estimator; 87 88 89 // These record the most recent collection times. They 90 // are available as an alternative to using the averages 91 // for making ergonomic decisions. 92 double _latest_major_mutator_interval_seconds; 93 94 const size_t _space_alignment; // alignment for eden, survivors 95 96 const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause 97 98 // The amount of live data in the heap at the last full GC, used 99 // as a baseline to help us determine when we need to perform the 100 // next full GC. 101 size_t _live_at_last_full_gc; 102 103 // decrease/increase the old generation for minor pause time 104 int _change_old_gen_for_min_pauses; 105 106 // increase/decrease the young generation for major pause time 107 int _change_young_gen_for_maj_pauses; 108 109 110 // Flag indicating that the adaptive policy is ready to use 111 bool _old_gen_policy_is_ready; 112 113 // To facilitate faster growth at start up, supplement the normal 114 // growth percentage for the young gen eden and the 115 // old gen space for promotion with these value which decay 116 // with increasing collections. 117 uint _young_gen_size_increment_supplement; 118 uint _old_gen_size_increment_supplement; 119 120 private: 121 122 // Accessors avg_major_pause() const123 AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; } gc_minor_pause_goal_sec() const124 double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; } 125 126 void adjust_eden_for_minor_pause_time(bool is_full_gc, 127 size_t* desired_eden_size_ptr); 128 // Change the generation sizes to achieve a GC pause time goal 129 // Returned sizes are not necessarily aligned. 130 void adjust_promo_for_pause_time(bool is_full_gc, 131 size_t* desired_promo_size_ptr, 132 size_t* desired_eden_size_ptr); 133 void adjust_eden_for_pause_time(bool is_full_gc, 134 size_t* desired_promo_size_ptr, 135 size_t* desired_eden_size_ptr); 136 // Change the generation sizes to achieve an application throughput goal 137 // Returned sizes are not necessarily aligned. 138 void adjust_promo_for_throughput(bool is_full_gc, 139 size_t* desired_promo_size_ptr); 140 void adjust_eden_for_throughput(bool is_full_gc, 141 size_t* desired_eden_size_ptr); 142 // Change the generation sizes to achieve minimum footprint 143 // Returned sizes are not aligned. 144 size_t adjust_promo_for_footprint(size_t desired_promo_size, 145 size_t desired_total); 146 size_t adjust_eden_for_footprint(size_t desired_promo_size, 147 size_t desired_total); 148 149 // Size in bytes for an increment or decrement of eden. 150 virtual size_t eden_increment(size_t cur_eden, uint percent_change); 151 virtual size_t eden_decrement(size_t cur_eden); 152 size_t eden_decrement_aligned_down(size_t cur_eden); 153 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden); 154 155 // Size in bytes for an increment or decrement of the promotion area 156 virtual size_t promo_increment(size_t cur_promo, uint percent_change); 157 virtual size_t promo_decrement(size_t cur_promo); 158 size_t promo_decrement_aligned_down(size_t cur_promo); 159 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo); 160 161 // Returns a change that has been scaled down. Result 162 // is not aligned. (If useful, move to some shared 163 // location.) 164 size_t scale_down(size_t change, double part, double total); 165 166 protected: 167 // Time accessors 168 169 // Footprint accessors live_space() const170 size_t live_space() const { 171 return (size_t)(avg_base_footprint()->average() + 172 avg_young_live()->average() + 173 avg_old_live()->average()); 174 } free_space() const175 size_t free_space() const { 176 return _eden_size + _promo_size; 177 } 178 set_promo_size(size_t new_size)179 void set_promo_size(size_t new_size) { 180 _promo_size = new_size; 181 } set_survivor_size(size_t new_size)182 void set_survivor_size(size_t new_size) { 183 _survivor_size = new_size; 184 } 185 186 // Update estimators 187 void update_minor_pause_old_estimator(double minor_pause_in_ms); 188 kind() const189 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; } 190 191 public: 192 virtual size_t eden_increment(size_t cur_eden); 193 virtual size_t promo_increment(size_t cur_promo); 194 195 // Accessors for use by performance counters avg_promoted() const196 AdaptivePaddedNoZeroDevAverage* avg_promoted() const { 197 return _gc_stats.avg_promoted(); 198 } avg_base_footprint() const199 AdaptiveWeightedAverage* avg_base_footprint() const { 200 return _avg_base_footprint; 201 } 202 203 // Input arguments are initial free space sizes for young and old 204 // generations, the initial survivor space size, the 205 // alignment values and the pause & throughput goals. 206 // 207 // NEEDS_CLEANUP this is a singleton object 208 PSAdaptiveSizePolicy(size_t init_eden_size, 209 size_t init_promo_size, 210 size_t init_survivor_size, 211 size_t space_alignment, 212 double gc_pause_goal_sec, 213 double gc_minor_pause_goal_sec, 214 uint gc_time_ratio); 215 216 // Methods indicating events of interest to the adaptive size policy, 217 // called by GC algorithms. It is the responsibility of users of this 218 // policy to call these methods at the correct times! 219 void major_collection_begin(); 220 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause); 221 tenured_allocation(size_t size)222 void tenured_allocation(size_t size) { 223 _avg_pretenured->sample(size); 224 } 225 226 // Accessors 227 // NEEDS_CLEANUP should use sizes.hpp 228 229 static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage); 230 231 size_t calculated_old_free_size_in_bytes() const; 232 average_old_live_in_bytes() const233 size_t average_old_live_in_bytes() const { 234 return (size_t) avg_old_live()->average(); 235 } 236 average_promoted_in_bytes() const237 size_t average_promoted_in_bytes() const { 238 return (size_t)avg_promoted()->average(); 239 } 240 padded_average_promoted_in_bytes() const241 size_t padded_average_promoted_in_bytes() const { 242 return (size_t)avg_promoted()->padded_average(); 243 } 244 change_young_gen_for_maj_pauses()245 int change_young_gen_for_maj_pauses() { 246 return _change_young_gen_for_maj_pauses; 247 } set_change_young_gen_for_maj_pauses(int v)248 void set_change_young_gen_for_maj_pauses(int v) { 249 _change_young_gen_for_maj_pauses = v; 250 } 251 change_old_gen_for_min_pauses()252 int change_old_gen_for_min_pauses() { 253 return _change_old_gen_for_min_pauses; 254 } set_change_old_gen_for_min_pauses(int v)255 void set_change_old_gen_for_min_pauses(int v) { 256 _change_old_gen_for_min_pauses = v; 257 } 258 259 // Return true if the old generation size was changed 260 // to try to reach a pause time goal. old_gen_changed_for_pauses()261 bool old_gen_changed_for_pauses() { 262 bool result = _change_old_gen_for_maj_pauses != 0 || 263 _change_old_gen_for_min_pauses != 0; 264 return result; 265 } 266 267 // Return true if the young generation size was changed 268 // to try to reach a pause time goal. young_gen_changed_for_pauses()269 bool young_gen_changed_for_pauses() { 270 bool result = _change_young_gen_for_min_pauses != 0 || 271 _change_young_gen_for_maj_pauses != 0; 272 return result; 273 } 274 // end flags for pause goal 275 276 // Return true if the old generation size was changed 277 // to try to reach a throughput goal. old_gen_changed_for_throughput()278 bool old_gen_changed_for_throughput() { 279 bool result = _change_old_gen_for_throughput != 0; 280 return result; 281 } 282 283 // Return true if the young generation size was changed 284 // to try to reach a throughput goal. young_gen_changed_for_throughput()285 bool young_gen_changed_for_throughput() { 286 bool result = _change_young_gen_for_throughput != 0; 287 return result; 288 } 289 decrease_for_footprint()290 int decrease_for_footprint() { return _decrease_for_footprint; } 291 292 293 // Accessors for estimators. The slope of the linear fit is 294 // currently all that is used for making decisions. 295 major_pause_old_estimator()296 LinearLeastSquareFit* major_pause_old_estimator() { 297 return _major_pause_old_estimator; 298 } 299 major_pause_young_estimator()300 LinearLeastSquareFit* major_pause_young_estimator() { 301 return _major_pause_young_estimator; 302 } 303 304 305 virtual void clear_generation_free_space_flags(); 306 major_pause_old_slope()307 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); } major_pause_young_slope()308 float major_pause_young_slope() { 309 return _major_pause_young_estimator->slope(); 310 } major_collection_slope()311 float major_collection_slope() { return _major_collection_estimator->slope();} 312 old_gen_policy_is_ready()313 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; } 314 315 // Given the amount of live data in the heap, should we 316 // perform a Full GC? 317 bool should_full_GC(size_t live_in_old_gen); 318 319 // Calculates optimal (free) space sizes for both the young and old 320 // generations. Stores results in _eden_size and _promo_size. 321 // Takes current used space in all generations as input, as well 322 // as an indication if a full gc has just been performed, for use 323 // in deciding if an OOM error should be thrown. 324 void compute_generations_free_space(size_t young_live, 325 size_t eden_live, 326 size_t old_live, 327 size_t cur_eden, // current eden in bytes 328 size_t max_old_gen_size, 329 size_t max_eden_size, 330 bool is_full_gc); 331 332 void compute_eden_space_size(size_t young_live, 333 size_t eden_live, 334 size_t cur_eden, // current eden in bytes 335 size_t max_eden_size, 336 bool is_full_gc); 337 338 void compute_old_gen_free_space(size_t old_live, 339 size_t cur_eden, // current eden in bytes 340 size_t max_old_gen_size, 341 bool is_full_gc); 342 343 // Calculates new survivor space size; returns a new tenuring threshold 344 // value. Stores new survivor size in _survivor_size. 345 uint compute_survivor_space_size_and_threshold(bool is_survivor_overflow, 346 uint tenuring_threshold, 347 size_t survivor_limit); 348 349 // Return the maximum size of a survivor space if the young generation were of 350 // size gen_size. max_survivor_size(size_t gen_size)351 size_t max_survivor_size(size_t gen_size) { 352 // Never allow the target survivor size to grow more than MinSurvivorRatio 353 // of the young generation size. We cannot grow into a two semi-space 354 // system, with Eden zero sized. Even if the survivor space grows, from() 355 // might grow by moving the bottom boundary "down" -- so from space will 356 // remain almost full anyway (top() will be near end(), but there will be a 357 // large filler object at the bottom). 358 const size_t sz = gen_size / MinSurvivorRatio; 359 const size_t alignment = _space_alignment; 360 return sz > alignment ? align_down(sz, alignment) : alignment; 361 } 362 live_at_last_full_gc()363 size_t live_at_last_full_gc() { 364 return _live_at_last_full_gc; 365 } 366 367 // Update averages that are always used (even 368 // if adaptive sizing is turned off). 369 void update_averages(bool is_survivor_overflow, 370 size_t survived, 371 size_t promoted); 372 373 // Printing support 374 virtual bool print() const; 375 376 // Decay the supplemental growth additive. 377 void decay_supplemental_growth(bool is_full_gc); 378 }; 379 380 #endif // SHARE_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP 381