1 /* 2 * Copyright (c) 2002, 2010, 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_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP 27 28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp" 29 #include "gc_implementation/shared/gcStats.hpp" 30 #include "gc_implementation/shared/gcUtil.hpp" 31 #include "gc_interface/gcCause.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 optimial 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 class GenerationSizer; 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 size_t _survivor_size_limit; // Limit in bytes of survivor size 79 const double _collection_cost_margin_fraction; 80 81 // Variable for estimating the major and minor pause times. 82 // These variables represent linear least-squares fits of 83 // the data. 84 // major pause time vs. old gen size 85 LinearLeastSquareFit* _major_pause_old_estimator; 86 // major pause time vs. young gen size 87 LinearLeastSquareFit* _major_pause_young_estimator; 88 89 90 // These record the most recent collection times. They 91 // are available as an alternative to using the averages 92 // for making ergonomic decisions. 93 double _latest_major_mutator_interval_seconds; 94 95 const size_t _intra_generation_alignment; // alignment for eden, survivors 96 97 const double _gc_minor_pause_goal_sec; // goal for maximum minor gc pause 98 99 // The amount of live data in the heap at the last full GC, used 100 // as a baseline to help us determine when we need to perform the 101 // next full GC. 102 size_t _live_at_last_full_gc; 103 104 // decrease/increase the old generation for minor pause time 105 int _change_old_gen_for_min_pauses; 106 107 // increase/decrease the young generation for major pause time 108 int _change_young_gen_for_maj_pauses; 109 110 111 // Flag indicating that the adaptive policy is ready to use 112 bool _old_gen_policy_is_ready; 113 114 // Changing the generation sizing depends on the data that is 115 // gathered about the effects of changes on the pause times and 116 // throughput. These variable count the number of data points 117 // gathered. The policy may use these counters as a threshhold 118 // for reliable data. 119 julong _young_gen_change_for_major_pause_count; 120 121 // To facilitate faster growth at start up, supplement the normal 122 // growth percentage for the young gen eden and the 123 // old gen space for promotion with these value which decay 124 // with increasing collections. 125 uint _young_gen_size_increment_supplement; 126 uint _old_gen_size_increment_supplement; 127 128 // The number of bytes absorbed from eden into the old gen by moving the 129 // boundary over live data. 130 size_t _bytes_absorbed_from_eden; 131 132 private: 133 134 // Accessors 135 AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; } 136 double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; } 137 138 // Change the young generation size to achieve a minor GC pause time goal 139 void adjust_for_minor_pause_time(bool is_full_gc, 140 size_t* desired_promo_size_ptr, 141 size_t* desired_eden_size_ptr); 142 // Change the generation sizes to achieve a GC pause time goal 143 // Returned sizes are not necessarily aligned. 144 void adjust_for_pause_time(bool is_full_gc, 145 size_t* desired_promo_size_ptr, 146 size_t* desired_eden_size_ptr); 147 // Change the generation sizes to achieve an application throughput goal 148 // Returned sizes are not necessarily aligned. 149 void adjust_for_throughput(bool is_full_gc, 150 size_t* desired_promo_size_ptr, 151 size_t* desired_eden_size_ptr); 152 // Change the generation sizes to achieve minimum footprint 153 // Returned sizes are not aligned. 154 size_t adjust_promo_for_footprint(size_t desired_promo_size, 155 size_t desired_total); 156 size_t adjust_eden_for_footprint(size_t desired_promo_size, 157 size_t desired_total); 158 159 // Size in bytes for an increment or decrement of eden. 160 virtual size_t eden_increment(size_t cur_eden, uint percent_change); 161 virtual size_t eden_decrement(size_t cur_eden); 162 size_t eden_decrement_aligned_down(size_t cur_eden); 163 size_t eden_increment_with_supplement_aligned_up(size_t cur_eden); 164 165 // Size in bytes for an increment or decrement of the promotion area 166 virtual size_t promo_increment(size_t cur_promo, uint percent_change); 167 virtual size_t promo_decrement(size_t cur_promo); 168 size_t promo_decrement_aligned_down(size_t cur_promo); 169 size_t promo_increment_with_supplement_aligned_up(size_t cur_promo); 170 171 // Decay the supplemental growth additive. 172 void decay_supplemental_growth(bool is_full_gc); 173 174 // Returns a change that has been scaled down. Result 175 // is not aligned. (If useful, move to some shared 176 // location.) 177 size_t scale_down(size_t change, double part, double total); 178 179 protected: 180 // Time accessors 181 182 // Footprint accessors 183 size_t live_space() const { 184 return (size_t)(avg_base_footprint()->average() + 185 avg_young_live()->average() + 186 avg_old_live()->average()); 187 } 188 size_t free_space() const { 189 return _eden_size + _promo_size; 190 } 191 192 void set_promo_size(size_t new_size) { 193 _promo_size = new_size; 194 } 195 void set_survivor_size(size_t new_size) { 196 _survivor_size = new_size; 197 } 198 199 // Update estimators 200 void update_minor_pause_old_estimator(double minor_pause_in_ms); 201 202 virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; } 203 204 public: 205 // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving. 206 size_t eden_increment_aligned_up(size_t cur_eden); 207 size_t eden_increment_aligned_down(size_t cur_eden); 208 size_t promo_increment_aligned_up(size_t cur_promo); 209 size_t promo_increment_aligned_down(size_t cur_promo); 210 211 virtual size_t eden_increment(size_t cur_eden); 212 virtual size_t promo_increment(size_t cur_promo); 213 214 // Accessors for use by performance counters 215 AdaptivePaddedNoZeroDevAverage* avg_promoted() const { 216 return _gc_stats.avg_promoted(); 217 } 218 AdaptiveWeightedAverage* avg_base_footprint() const { 219 return _avg_base_footprint; 220 } 221 222 // Input arguments are initial free space sizes for young and old 223 // generations, the initial survivor space size, the 224 // alignment values and the pause & throughput goals. 225 // 226 // NEEDS_CLEANUP this is a singleton object 227 PSAdaptiveSizePolicy(size_t init_eden_size, 228 size_t init_promo_size, 229 size_t init_survivor_size, 230 size_t intra_generation_alignment, 231 double gc_pause_goal_sec, 232 double gc_minor_pause_goal_sec, 233 uint gc_time_ratio); 234 235 // Methods indicating events of interest to the adaptive size policy, 236 // called by GC algorithms. It is the responsibility of users of this 237 // policy to call these methods at the correct times! 238 void major_collection_begin(); 239 void major_collection_end(size_t amount_live, GCCause::Cause gc_cause); 240 241 void tenured_allocation(size_t size) { 242 _avg_pretenured->sample(size); 243 } 244 245 // Accessors 246 // NEEDS_CLEANUP should use sizes.hpp 247 248 static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage); 249 250 size_t calculated_old_free_size_in_bytes() const; 251 252 size_t average_old_live_in_bytes() const { 253 return (size_t) avg_old_live()->average(); 254 } 255 256 size_t average_promoted_in_bytes() const { 257 return (size_t)avg_promoted()->average(); 258 } 259 260 size_t padded_average_promoted_in_bytes() const { 261 return (size_t)avg_promoted()->padded_average(); 262 } 263 264 int change_young_gen_for_maj_pauses() { 265 return _change_young_gen_for_maj_pauses; 266 } 267 void set_change_young_gen_for_maj_pauses(int v) { 268 _change_young_gen_for_maj_pauses = v; 269 } 270 271 int change_old_gen_for_min_pauses() { 272 return _change_old_gen_for_min_pauses; 273 } 274 void set_change_old_gen_for_min_pauses(int v) { 275 _change_old_gen_for_min_pauses = v; 276 } 277 278 // Return true if the old generation size was changed 279 // to try to reach a pause time goal. 280 bool old_gen_changed_for_pauses() { 281 bool result = _change_old_gen_for_maj_pauses != 0 || 282 _change_old_gen_for_min_pauses != 0; 283 return result; 284 } 285 286 // Return true if the young generation size was changed 287 // to try to reach a pause time goal. 288 bool young_gen_changed_for_pauses() { 289 bool result = _change_young_gen_for_min_pauses != 0 || 290 _change_young_gen_for_maj_pauses != 0; 291 return result; 292 } 293 // end flags for pause goal 294 295 // Return true if the old generation size was changed 296 // to try to reach a throughput goal. 297 bool old_gen_changed_for_throughput() { 298 bool result = _change_old_gen_for_throughput != 0; 299 return result; 300 } 301 302 // Return true if the young generation size was changed 303 // to try to reach a throughput goal. 304 bool young_gen_changed_for_throughput() { 305 bool result = _change_young_gen_for_throughput != 0; 306 return result; 307 } 308 309 int decrease_for_footprint() { return _decrease_for_footprint; } 310 311 312 // Accessors for estimators. The slope of the linear fit is 313 // currently all that is used for making decisions. 314 315 LinearLeastSquareFit* major_pause_old_estimator() { 316 return _major_pause_old_estimator; 317 } 318 319 LinearLeastSquareFit* major_pause_young_estimator() { 320 return _major_pause_young_estimator; 321 } 322 323 324 virtual void clear_generation_free_space_flags(); 325 326 float major_pause_old_slope() { return _major_pause_old_estimator->slope(); } 327 float major_pause_young_slope() { 328 return _major_pause_young_estimator->slope(); 329 } 330 float major_collection_slope() { return _major_collection_estimator->slope();} 331 332 bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; } 333 334 // Given the amount of live data in the heap, should we 335 // perform a Full GC? 336 bool should_full_GC(size_t live_in_old_gen); 337 338 // Calculates optimial free space sizes for both the old and young 339 // generations. Stores results in _eden_size and _promo_size. 340 // Takes current used space in all generations as input, as well 341 // as an indication if a full gc has just been performed, for use 342 // in deciding if an OOM error should be thrown. 343 void compute_generation_free_space(size_t young_live, 344 size_t eden_live, 345 size_t old_live, 346 size_t perm_live, 347 size_t cur_eden, // current eden in bytes 348 size_t max_old_gen_size, 349 size_t max_eden_size, 350 bool is_full_gc, 351 GCCause::Cause gc_cause, 352 CollectorPolicy* collector_policy); 353 354 // Calculates new survivor space size; returns a new tenuring threshold 355 // value. Stores new survivor size in _survivor_size. 356 int compute_survivor_space_size_and_threshold(bool is_survivor_overflow, 357 int tenuring_threshold, 358 size_t survivor_limit); 359 360 // Return the maximum size of a survivor space if the young generation were of 361 // size gen_size. 362 size_t max_survivor_size(size_t gen_size) { 363 // Never allow the target survivor size to grow more than MinSurvivorRatio 364 // of the young generation size. We cannot grow into a two semi-space 365 // system, with Eden zero sized. Even if the survivor space grows, from() 366 // might grow by moving the bottom boundary "down" -- so from space will 367 // remain almost full anyway (top() will be near end(), but there will be a 368 // large filler object at the bottom). 369 const size_t sz = gen_size / MinSurvivorRatio; 370 const size_t alignment = _intra_generation_alignment; 371 return sz > alignment ? align_size_down(sz, alignment) : alignment; 372 } 373 374 size_t live_at_last_full_gc() { 375 return _live_at_last_full_gc; 376 } 377 378 size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; } 379 void reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; } 380 381 void set_bytes_absorbed_from_eden(size_t val) { 382 _bytes_absorbed_from_eden = val; 383 } 384 385 // Update averages that are always used (even 386 // if adaptive sizing is turned off). 387 void update_averages(bool is_survivor_overflow, 388 size_t survived, 389 size_t promoted); 390 391 // Printing support 392 virtual bool print_adaptive_size_policy_on(outputStream* st) const; 393 }; 394 395 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSADAPTIVESIZEPOLICY_HPP