1 /* 2 * Copyright (c) 2004, 2006, 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 // This class keeps statistical information and computes the 26 // size of the heap for the concurrent mark sweep collector. 27 // 28 // Cost for garbage collector include cost for 29 // minor collection 30 // concurrent collection 31 // stop-the-world component 32 // concurrent component 33 // major compacting collection 34 // uses decaying cost 35 36 // Forward decls 37 class elapsedTimer; 38 39 class CMSAdaptiveSizePolicy : public AdaptiveSizePolicy { 40 friend class CMSGCAdaptivePolicyCounters; 41 friend class CMSCollector; 42 private: 43 44 // Total number of processors available 45 int _processor_count; 46 // Number of processors used by the concurrent phases of GC 47 // This number is assumed to be the same for all concurrent 48 // phases. 49 int _concurrent_processor_count; 50 51 // Time that the mutators run exclusive of a particular 52 // phase. For example, the time the mutators run excluding 53 // the time during which the cms collector runs concurrently 54 // with the mutators. 55 // Between end of most recent cms reset and start of initial mark 56 // This may be redundant 57 double _latest_cms_reset_end_to_initial_mark_start_secs; 58 // Between end of the most recent initial mark and start of remark 59 double _latest_cms_initial_mark_end_to_remark_start_secs; 60 // Between end of most recent collection and start of 61 // a concurrent collection 62 double _latest_cms_collection_end_to_collection_start_secs; 63 // Times of the concurrent phases of the most recent 64 // concurrent collection 65 double _latest_cms_concurrent_marking_time_secs; 66 double _latest_cms_concurrent_precleaning_time_secs; 67 double _latest_cms_concurrent_sweeping_time_secs; 68 // Between end of most recent STW MSC and start of next STW MSC 69 double _latest_cms_msc_end_to_msc_start_time_secs; 70 // Between end of most recent MS and start of next MS 71 // This does not include any time spent during a concurrent 72 // collection. 73 double _latest_cms_ms_end_to_ms_start; 74 // Between start and end of the initial mark of the most recent 75 // concurrent collection. 76 double _latest_cms_initial_mark_start_to_end_time_secs; 77 // Between start and end of the remark phase of the most recent 78 // concurrent collection 79 double _latest_cms_remark_start_to_end_time_secs; 80 // Between start and end of the most recent MS STW marking phase 81 double _latest_cms_ms_marking_start_to_end_time_secs; 82 83 // Pause time timers 84 static elapsedTimer _STW_timer; 85 // Concurrent collection timer. Used for total of all concurrent phases 86 // during 1 collection cycle. 87 static elapsedTimer _concurrent_timer; 88 89 // When the size of the generation is changed, the size 90 // of the change will rounded up or down (depending on the 91 // type of change) by this value. 92 size_t _generation_alignment; 93 94 // If this variable is true, the size of the young generation 95 // may be changed in order to reduce the pause(s) of the 96 // collection of the tenured generation in order to meet the 97 // pause time goal. It is common to change the size of the 98 // tenured generation in order to meet the pause time goal 99 // for the tenured generation. With the CMS collector for 100 // the tenured generation, the size of the young generation 101 // can have an significant affect on the pause times for collecting the 102 // tenured generation. 103 // This is a duplicate of a variable in PSAdaptiveSizePolicy. It 104 // is duplicated because it is not clear that it is general enough 105 // to go into AdaptiveSizePolicy. 106 int _change_young_gen_for_maj_pauses; 107 108 // Variable that is set to true after a collection. 109 bool _first_after_collection; 110 111 // Fraction of collections that are of each type 112 double concurrent_fraction() const; 113 double STW_msc_fraction() const; 114 double STW_ms_fraction() const; 115 116 // This call cannot be put into the epilogue as long as some 117 // of the counters can be set during concurrent phases. 118 virtual void clear_generation_free_space_flags(); 119 120 void set_first_after_collection() { _first_after_collection = true; } 121 122 protected: 123 // Average of the sum of the concurrent times for 124 // one collection in seconds. 125 AdaptiveWeightedAverage* _avg_concurrent_time; 126 // Average time between concurrent collections in seconds. 127 AdaptiveWeightedAverage* _avg_concurrent_interval; 128 // Average cost of the concurrent part of a collection 129 // in seconds. 130 AdaptiveWeightedAverage* _avg_concurrent_gc_cost; 131 132 // Average of the initial pause of a concurrent collection in seconds. 133 AdaptivePaddedAverage* _avg_initial_pause; 134 // Average of the remark pause of a concurrent collection in seconds. 135 AdaptivePaddedAverage* _avg_remark_pause; 136 137 // Average of the stop-the-world (STW) (initial mark + remark) 138 // times in seconds for concurrent collections. 139 AdaptiveWeightedAverage* _avg_cms_STW_time; 140 // Average of the STW collection cost for concurrent collections. 141 AdaptiveWeightedAverage* _avg_cms_STW_gc_cost; 142 143 // Average of the bytes free at the start of the sweep. 144 AdaptiveWeightedAverage* _avg_cms_free_at_sweep; 145 // Average of the bytes free at the end of the collection. 146 AdaptiveWeightedAverage* _avg_cms_free; 147 // Average of the bytes promoted between cms collections. 148 AdaptiveWeightedAverage* _avg_cms_promo; 149 150 // stop-the-world (STW) mark-sweep-compact 151 // Average of the pause time in seconds for STW mark-sweep-compact 152 // collections. 153 AdaptiveWeightedAverage* _avg_msc_pause; 154 // Average of the interval in seconds between STW mark-sweep-compact 155 // collections. 156 AdaptiveWeightedAverage* _avg_msc_interval; 157 // Average of the collection costs for STW mark-sweep-compact 158 // collections. 159 AdaptiveWeightedAverage* _avg_msc_gc_cost; 160 161 // Averages for mark-sweep collections. 162 // The collection may have started as a background collection 163 // that completes in a stop-the-world (STW) collection. 164 // Average of the pause time in seconds for mark-sweep 165 // collections. 166 AdaptiveWeightedAverage* _avg_ms_pause; 167 // Average of the interval in seconds between mark-sweep 168 // collections. 169 AdaptiveWeightedAverage* _avg_ms_interval; 170 // Average of the collection costs for mark-sweep 171 // collections. 172 AdaptiveWeightedAverage* _avg_ms_gc_cost; 173 174 // These variables contain a linear fit of 175 // a generation size as the independent variable 176 // and a pause time as the dependent variable. 177 // For example _remark_pause_old_estimator 178 // is a fit of the old generation size as the 179 // independent variable and the remark pause 180 // as the dependent variable. 181 // remark pause time vs. cms gen size 182 LinearLeastSquareFit* _remark_pause_old_estimator; 183 // initial pause time vs. cms gen size 184 LinearLeastSquareFit* _initial_pause_old_estimator; 185 // remark pause time vs. young gen size 186 LinearLeastSquareFit* _remark_pause_young_estimator; 187 // initial pause time vs. young gen size 188 LinearLeastSquareFit* _initial_pause_young_estimator; 189 190 // Accessors 191 int processor_count() const { return _processor_count; } 192 int concurrent_processor_count() const { return _concurrent_processor_count; } 193 194 AdaptiveWeightedAverage* avg_concurrent_time() const { 195 return _avg_concurrent_time; 196 } 197 198 AdaptiveWeightedAverage* avg_concurrent_interval() const { 199 return _avg_concurrent_interval; 200 } 201 202 AdaptiveWeightedAverage* avg_concurrent_gc_cost() const { 203 return _avg_concurrent_gc_cost; 204 } 205 206 AdaptiveWeightedAverage* avg_cms_STW_time() const { 207 return _avg_cms_STW_time; 208 } 209 210 AdaptiveWeightedAverage* avg_cms_STW_gc_cost() const { 211 return _avg_cms_STW_gc_cost; 212 } 213 214 AdaptivePaddedAverage* avg_initial_pause() const { 215 return _avg_initial_pause; 216 } 217 218 AdaptivePaddedAverage* avg_remark_pause() const { 219 return _avg_remark_pause; 220 } 221 222 AdaptiveWeightedAverage* avg_cms_free() const { 223 return _avg_cms_free; 224 } 225 226 AdaptiveWeightedAverage* avg_cms_free_at_sweep() const { 227 return _avg_cms_free_at_sweep; 228 } 229 230 AdaptiveWeightedAverage* avg_msc_pause() const { 231 return _avg_msc_pause; 232 } 233 234 AdaptiveWeightedAverage* avg_msc_interval() const { 235 return _avg_msc_interval; 236 } 237 238 AdaptiveWeightedAverage* avg_msc_gc_cost() const { 239 return _avg_msc_gc_cost; 240 } 241 242 AdaptiveWeightedAverage* avg_ms_pause() const { 243 return _avg_ms_pause; 244 } 245 246 AdaptiveWeightedAverage* avg_ms_interval() const { 247 return _avg_ms_interval; 248 } 249 250 AdaptiveWeightedAverage* avg_ms_gc_cost() const { 251 return _avg_ms_gc_cost; 252 } 253 254 LinearLeastSquareFit* remark_pause_old_estimator() { 255 return _remark_pause_old_estimator; 256 } 257 LinearLeastSquareFit* initial_pause_old_estimator() { 258 return _initial_pause_old_estimator; 259 } 260 LinearLeastSquareFit* remark_pause_young_estimator() { 261 return _remark_pause_young_estimator; 262 } 263 LinearLeastSquareFit* initial_pause_young_estimator() { 264 return _initial_pause_young_estimator; 265 } 266 267 // These *slope() methods return the slope 268 // m for the linear fit of an independent 269 // variable vs. a dependent variable. For 270 // example 271 // remark_pause = m * old_generation_size + c 272 // These may be used to determine if an 273 // adjustment should be made to achieve a goal. 274 // For example, if remark_pause_old_slope() is 275 // positive, a reduction of the old generation 276 // size has on average resulted in the reduction 277 // of the remark pause. 278 float remark_pause_old_slope() { 279 return _remark_pause_old_estimator->slope(); 280 } 281 282 float initial_pause_old_slope() { 283 return _initial_pause_old_estimator->slope(); 284 } 285 286 float remark_pause_young_slope() { 287 return _remark_pause_young_estimator->slope(); 288 } 289 290 float initial_pause_young_slope() { 291 return _initial_pause_young_estimator->slope(); 292 } 293 294 // Update estimators 295 void update_minor_pause_old_estimator(double minor_pause_in_ms); 296 297 // Fraction of processors used by the concurrent phases. 298 double concurrent_processor_fraction(); 299 300 // Returns the total times for the concurrent part of the 301 // latest collection in seconds. 302 double concurrent_collection_time(); 303 304 // Return the total times for the concurrent part of the 305 // latest collection in seconds where the times of the various 306 // concurrent phases are scaled by the processor fraction used 307 // during the phase. 308 double scaled_concurrent_collection_time(); 309 310 // Dimensionless concurrent GC cost for all the concurrent phases. 311 double concurrent_collection_cost(double interval_in_seconds); 312 313 // Dimensionless GC cost 314 double collection_cost(double pause_in_seconds, double interval_in_seconds); 315 316 virtual GCPolicyKind kind() const { return _gc_cms_adaptive_size_policy; } 317 318 virtual double time_since_major_gc() const; 319 320 // This returns the maximum average for the concurrent, ms, and 321 // msc collections. This is meant to be used for the calculation 322 // of the decayed major gc cost and is not in general the 323 // average of all the different types of major collections. 324 virtual double major_gc_interval_average_for_decay() const; 325 326 public: 327 CMSAdaptiveSizePolicy(size_t init_eden_size, 328 size_t init_promo_size, 329 size_t init_survivor_size, 330 double max_gc_minor_pause_sec, 331 double max_gc_pause_sec, 332 uint gc_cost_ratio); 333 334 // The timers for the stop-the-world phases measure a total 335 // stop-the-world time. The timer is started and stopped 336 // for each phase but is only reset after the final checkpoint. 337 void checkpoint_roots_initial_begin(); 338 void checkpoint_roots_initial_end(GCCause::Cause gc_cause); 339 void checkpoint_roots_final_begin(); 340 void checkpoint_roots_final_end(GCCause::Cause gc_cause); 341 342 // Methods for gathering information about the 343 // concurrent marking phase of the collection. 344 // Records the mutator times and 345 // resets the concurrent timer. 346 void concurrent_marking_begin(); 347 // Resets concurrent phase timer in the begin methods and 348 // saves the time for a phase in the end methods. 349 void concurrent_marking_end(); 350 void concurrent_sweeping_begin(); 351 void concurrent_sweeping_end(); 352 // Similar to the above (e.g., concurrent_marking_end()) and 353 // is used for both the precleaning an abortable precleaing 354 // phases. 355 void concurrent_precleaning_begin(); 356 void concurrent_precleaning_end(); 357 // Stops the concurrent phases time. Gathers 358 // information and resets the timer. 359 void concurrent_phases_end(GCCause::Cause gc_cause, 360 size_t cur_eden, 361 size_t cur_promo); 362 363 // Methods for gather information about STW Mark-Sweep-Compact 364 void msc_collection_begin(); 365 void msc_collection_end(GCCause::Cause gc_cause); 366 367 // Methods for gather information about Mark-Sweep done 368 // in the foreground. 369 void ms_collection_begin(); 370 void ms_collection_end(GCCause::Cause gc_cause); 371 372 // Cost for a mark-sweep tenured gen collection done in the foreground 373 double ms_gc_cost() const { 374 return MAX2(0.0F, _avg_ms_gc_cost->average()); 375 } 376 377 // Cost of collecting the tenured generation. Includes 378 // concurrent collection and STW collection costs 379 double cms_gc_cost() const; 380 381 // Cost of STW mark-sweep-compact tenured gen collection. 382 double msc_gc_cost() const { 383 return MAX2(0.0F, _avg_msc_gc_cost->average()); 384 } 385 386 // 387 double compacting_gc_cost() const { 388 double result = MIN2(1.0, minor_gc_cost() + msc_gc_cost()); 389 assert(result >= 0.0, "Both minor and major costs are non-negative"); 390 return result; 391 } 392 393 // Restarts the concurrent phases timer. 394 void concurrent_phases_resume(); 395 396 // Time beginning and end of the marking phase for 397 // a synchronous MS collection. A MS collection 398 // that finishes in the foreground can have started 399 // in the background. These methods capture the 400 // completion of the marking (after the initial 401 // marking) that is done in the foreground. 402 void ms_collection_marking_begin(); 403 void ms_collection_marking_end(GCCause::Cause gc_cause); 404 405 static elapsedTimer* concurrent_timer_ptr() { 406 return &_concurrent_timer; 407 } 408 409 AdaptiveWeightedAverage* avg_cms_promo() const { 410 return _avg_cms_promo; 411 } 412 413 int change_young_gen_for_maj_pauses() { 414 return _change_young_gen_for_maj_pauses; 415 } 416 void set_change_young_gen_for_maj_pauses(int v) { 417 _change_young_gen_for_maj_pauses = v; 418 } 419 420 void clear_internal_time_intervals(); 421 422 423 // Either calculated_promo_size_in_bytes() or promo_size() 424 // should be deleted. 425 size_t promo_size() { return _promo_size; } 426 void set_promo_size(size_t v) { _promo_size = v; } 427 428 // Cost of GC for all types of collections. 429 virtual double gc_cost() const; 430 431 size_t generation_alignment() { return _generation_alignment; } 432 433 virtual void compute_young_generation_free_space(size_t cur_eden, 434 size_t max_eden_size); 435 // Calculates new survivor space size; returns a new tenuring threshold 436 // value. Stores new survivor size in _survivor_size. 437 virtual int compute_survivor_space_size_and_threshold( 438 bool is_survivor_overflow, 439 int tenuring_threshold, 440 size_t survivor_limit); 441 442 virtual void compute_tenured_generation_free_space(size_t cur_tenured_free, 443 size_t max_tenured_available, 444 size_t cur_eden); 445 446 size_t eden_decrement_aligned_down(size_t cur_eden); 447 size_t eden_increment_aligned_up(size_t cur_eden); 448 449 size_t adjust_eden_for_pause_time(size_t cur_eden); 450 size_t adjust_eden_for_throughput(size_t cur_eden); 451 size_t adjust_eden_for_footprint(size_t cur_eden); 452 453 size_t promo_decrement_aligned_down(size_t cur_promo); 454 size_t promo_increment_aligned_up(size_t cur_promo); 455 456 size_t adjust_promo_for_pause_time(size_t cur_promo); 457 size_t adjust_promo_for_throughput(size_t cur_promo); 458 size_t adjust_promo_for_footprint(size_t cur_promo, size_t cur_eden); 459 460 // Scale down the input size by the ratio of the cost to collect the 461 // generation to the total GC cost. 462 size_t scale_by_gen_gc_cost(size_t base_change, double gen_gc_cost); 463 464 // Return the value and clear it. 465 bool get_and_clear_first_after_collection(); 466 467 // Printing support 468 virtual bool print_adaptive_size_policy_on(outputStream* st) const; 469 };