1 /* 2 * Copyright (c) 2002, 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_PARALLEL_PSADAPTIVESIZEPOLICY_HPP 26 #define SHARE_VM_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 33 // This class keeps statistical information and computes the 34 // optimal free space for both the young and old generation 35 // based on current application characteristics (based on gc cost 36 // and application footprint). 37 // 38 // It also computes an optimal tenuring threshold between the young 39 // and old generations, so as to equalize the cost of collections 40 // of those generations, as well as optimal survivor space sizes 41 // for the young generation. 42 // 43 // While this class is specifically intended for a generational system 44 // consisting of a young gen (containing an Eden and two semi-spaces) 45 // and a tenured gen, as well as a perm gen for reflective data, it 46 // makes NO references to specific generations. 47 // 48 // 05/02/2003 Update 49 // The 1.5 policy makes use of data gathered for the costs of GC on 50 // specific generations. That data does reference specific 51 // generation. Also diagnostics specific to generations have 52 // been added. 53 54 // Forward decls 55 class elapsedTimer; 56 57 class PSAdaptiveSizePolicy : public AdaptiveSizePolicy { 58 friend class PSGCAdaptivePolicyCounters; 59 private: 60 // These values are used to record decisions made during the 61 // policy. For example, if the young generation was decreased 62 // to decrease the GC cost of minor collections the value 63 // decrease_young_gen_for_throughput_true is used. 64 65 // Last calculated sizes, in bytes, and aligned 66 // NEEDS_CLEANUP should use sizes.hpp, but it works in ints, not size_t's 67 68 // Time statistics 69 AdaptivePaddedAverage* _avg_major_pause; 70 71 // Footprint statistics 72 AdaptiveWeightedAverage* _avg_base_footprint; 73 74 // Statistical data gathered for GC 75 GCStats _gc_stats; 76 77 size_t _survivor_size_limit; // Limit in bytes of survivor size 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 // Changing the generation sizing depends on the data that is 114 // gathered about the effects of changes on the pause times and 115 // throughput. These variable count the number of data points 116 // gathered. The policy may use these counters as a threshold 117 // for reliable data. 118 julong _young_gen_change_for_major_pause_count; 119 120 // To facilitate faster growth at start up, supplement the normal 121 // growth percentage for the young gen eden and the 122 // old gen space for promotion with these value which decay 123 // with increasing collections. 124 uint _young_gen_size_increment_supplement; 125 uint _old_gen_size_increment_supplement; 126 127 // The number of bytes absorbed from eden into the old gen by moving the 128 // boundary over live data. 129 size_t _bytes_absorbed_from_eden; 130 131 private: 132 133 // Accessors 134 AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; } 135 double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; } 136 137 // Change the young generation size to achieve a minor GC pause time goal 138 void adjust_promo_for_minor_pause_time(bool is_full_gc, 139 size_t* desired_promo_size_ptr, 140 size_t* desired_eden_size_ptr); 141 void adjust_eden_for_minor_pause_time(bool is_full_gc, 142 size_t* desired_eden_size_ptr); 143 // Change the generation sizes to achieve a GC pause time goal 144 // Returned sizes are not necessarily aligned. 145 void adjust_promo_for_pause_time(bool is_full_gc, 146 size_t* desired_promo_size_ptr, 147 size_t* desired_eden_size_ptr); 148 void adjust_eden_for_pause_time(bool is_full_gc, 149 size_t* desired_promo_size_ptr, 150 size_t* desired_eden_size_ptr); 151 // Change the generation sizes to achieve an application throughput goal 152 // Returned sizes are not necessarily aligned. 153 void adjust_promo_for_throughput(bool is_full_gc, 154 size_t* desired_promo_size_ptr); 155 void adjust_eden_for_throughput(bool is_full_gc, 156 size_t* desired_eden_size_ptr); 157 // Change the generation sizes to achieve minimum footprint 158 // Returned sizes are not aligned. 159 size_t adjust_promo_for_footprint(size_t desired_promo_size, 160 size_t desired_total); 161 size_t adjust_eden_for_footprint(size_t desired_promo_size, 162 size_t desired_total); 163 164 // Size in bytes for an increment or decrement of eden. 165 virtual size_t eden_increment(size_t cur_eden, uint percent_change); 166 virtual size_t eden_decrement(size_t cur_eden); 167 size_t eden_decrement_aligned_down(size_t cur_eden); 168 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden); 169 170 // Size in bytes for an increment or decrement of the promotion area 171 virtual size_t promo_increment(size_t cur_promo, uint percent_change); 172 virtual size_t promo_decrement(size_t cur_promo); 173 size_t promo_decrement_aligned_down(size_t cur_promo); 174 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo); 175 176 // Returns a change that has been scaled down. Result 177 // is not aligned. (If useful, move to some shared 178 // location.) 179 size_t scale_down(size_t change, double part, double total); 180 181 protected: 182 // Time accessors 183 184 // Footprint accessors 185 size_t live_space() const { 186 return (size_t)(avg_base_footprint()->average() + 187 avg_young_live()->average() + 188 avg_old_live()->average()); 189 } 190 size_t free_space() const { 191 return _eden_size + _promo_size; 192 } 193 194 void set_promo_size(size_t new_size) { 195 _promo_size = new_size; 196 } 197 void set_survivor_size(size_t new_size) { 198 _survivor_size = new_size; 199 } 200 201 // Update estimators 202 void update_minor_pause_old_estimator(double minor_pause_in_ms); 203 204 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; } 205 206 public: 207 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving. 208 size_t eden_increment_aligned_up(size_t cur_eden); 209 size_t eden_increment_aligned_down(size_t cur_eden); 210 size_t promo_increment_aligned_up(size_t cur_promo); 211 size_t promo_increment_aligned_down(size_t cur_promo); 212 213 virtual size_t eden_increment(size_t cur_eden); 214 virtual size_t promo_increment(size_t cur_promo); 215 216 // Accessors for use by performance counters 217 AdaptivePaddedNoZeroDevAverage* avg_promoted() const { 218 return _gc_stats.avg_promoted(); 219 } 220 AdaptiveWeightedAverage* avg_base_footprint() const { 221 return _avg_base_footprint; 222 } 223 224 // Input arguments are initial free space sizes for young and old 225 // generations, the initial survivor space size, the 226 // alignment values and the pause & throughput goals. 227 // 228 // NEEDS_CLEANUP this is a singleton object 229 PSAdaptiveSizePolicy(size_t init_eden_size, 230 size_t init_promo_size, 231 size_t init_survivor_size, 232 size_t space_alignment, 233 double gc_pause_goal_sec, 234 double gc_minor_pause_goal_sec, 235 uint gc_time_ratio); 236 237 // Methods indicating events of interest to the adaptive size policy, 238 // called by GC algorithms. It is the responsibility of users of this 239 // policy to call these methods at the correct times! 240 void major_collection_begin(); 241 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause); 242 243 void tenured_allocation(size_t size) { 244 _avg_pretenured->sample(size); 245 } 246 247 // Accessors 248 // NEEDS_CLEANUP should use sizes.hpp 249 250 static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage); 251 252 size_t calculated_old_free_size_in_bytes() const; 253 254 size_t average_old_live_in_bytes() const { 255 return (size_t) avg_old_live()->average(); 256 } 257 258 size_t average_promoted_in_bytes() const { 259 return (size_t)avg_promoted()->average(); 260 } 261 262 size_t padded_average_promoted_in_bytes() const { 263 return (size_t)avg_promoted()->padded_average(); 264 } 265 266 int change_young_gen_for_maj_pauses() { 267 return _change_young_gen_for_maj_pauses; 268 } 269 void set_change_young_gen_for_maj_pauses(int v) { 270 _change_young_gen_for_maj_pauses = v; 271 } 272 273 int change_old_gen_for_min_pauses() { 274 return _change_old_gen_for_min_pauses; 275 } 276 void set_change_old_gen_for_min_pauses(int v) { 277 _change_old_gen_for_min_pauses = v; 278 } 279 280 // Return true if the old generation size was changed 281 // to try to reach a pause time goal. 282 bool old_gen_changed_for_pauses() { 283 bool result = _change_old_gen_for_maj_pauses != 0 || 284 _change_old_gen_for_min_pauses != 0; 285 return result; 286 } 287 288 // Return true if the young generation size was changed 289 // to try to reach a pause time goal. 290 bool young_gen_changed_for_pauses() { 291 bool result = _change_young_gen_for_min_pauses != 0 || 292 _change_young_gen_for_maj_pauses != 0; 293 return result; 294 } 295 // end flags for pause goal 296 297 // Return true if the old generation size was changed 298 // to try to reach a throughput goal. 299 bool old_gen_changed_for_throughput() { 300 bool result = _change_old_gen_for_throughput != 0; 301 return result; 302 } 303 304 // Return true if the young generation size was changed 305 // to try to reach a throughput goal. 306 bool young_gen_changed_for_throughput() { 307 bool result = _change_young_gen_for_throughput != 0; 308 return result; 309 } 310 311 int decrease_for_footprint() { return _decrease_for_footprint; } 312 313 314 // Accessors for estimators. The slope of the linear fit is 315 // currently all that is used for making decisions. 316 317 LinearLeastSquareFit* major_pause_old_estimator() { 318 return _major_pause_old_estimator; 319 } 320 321 LinearLeastSquareFit* major_pause_young_estimator() { 322 return _major_pause_young_estimator; 323 } 324 325 326 virtual void clear_generation_free_space_flags(); 327 328 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); } 329 float major_pause_young_slope() { 330 return _major_pause_young_estimator->slope(); 331 } 332 float major_collection_slope() { return _major_collection_estimator->slope();} 333 334 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; } 335 336 // Given the amount of live data in the heap, should we 337 // perform a Full GC? 338 bool should_full_GC(size_t live_in_old_gen); 339 340 // Calculates optimal (free) space sizes for both the young and old 341 // generations. Stores results in _eden_size and _promo_size. 342 // Takes current used space in all generations as input, as well 343 // as an indication if a full gc has just been performed, for use 344 // in deciding if an OOM error should be thrown. 345 void compute_generations_free_space(size_t young_live, 346 size_t eden_live, 347 size_t old_live, 348 size_t cur_eden, // current eden in bytes 349 size_t max_old_gen_size, 350 size_t max_eden_size, 351 bool is_full_gc); 352 353 void compute_eden_space_size(size_t young_live, 354 size_t eden_live, 355 size_t cur_eden, // current eden in bytes 356 size_t max_eden_size, 357 bool is_full_gc); 358 359 void compute_old_gen_free_space(size_t old_live, 360 size_t cur_eden, // current eden in bytes 361 size_t max_old_gen_size, 362 bool is_full_gc); 363 364 // Calculates new survivor space size; returns a new tenuring threshold 365 // value. Stores new survivor size in _survivor_size. 366 uint compute_survivor_space_size_and_threshold(bool is_survivor_overflow, 367 uint tenuring_threshold, 368 size_t survivor_limit); 369 370 // Return the maximum size of a survivor space if the young generation were of 371 // size gen_size. 372 size_t max_survivor_size(size_t gen_size) { 373 // Never allow the target survivor size to grow more than MinSurvivorRatio 374 // of the young generation size. We cannot grow into a two semi-space 375 // system, with Eden zero sized. Even if the survivor space grows, from() 376 // might grow by moving the bottom boundary "down" -- so from space will 377 // remain almost full anyway (top() will be near end(), but there will be a 378 // large filler object at the bottom). 379 const size_t sz = gen_size / MinSurvivorRatio; 380 const size_t alignment = _space_alignment; 381 return sz > alignment ? align_size_down(sz, alignment) : alignment; 382 } 383 384 size_t live_at_last_full_gc() { 385 return _live_at_last_full_gc; 386 } 387 388 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; } 389 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; } 390 391 void set_bytes_absorbed_from_eden(size_t val) { 392 _bytes_absorbed_from_eden = val; 393 } 394 395 // Update averages that are always used (even 396 // if adaptive sizing is turned off). 397 void update_averages(bool is_survivor_overflow, 398 size_t survived, 399 size_t promoted); 400 401 // Printing support 402 virtual bool print_adaptive_size_policy_on(outputStream* st) const; 403 404 // Decay the supplemental growth additive. 405 void decay_supplemental_growth(bool is_full_gc); 406 }; 407 408 #endif // SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP