1 /* 2 * Copyright (c) 2004, 2016, 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 #include "precompiled.hpp" 26 #include "gc/shared/adaptiveSizePolicy.hpp" 27 #include "gc/shared/collectorPolicy.hpp" 28 #include "gc/shared/gcCause.hpp" 29 #include "gc/shared/workgroup.hpp" 30 #include "logging/log.hpp" 31 #include "runtime/timer.hpp" 32 #include "utilities/ostream.hpp" 33 elapsedTimer AdaptiveSizePolicy::_minor_timer; 34 elapsedTimer AdaptiveSizePolicy::_major_timer; 35 bool AdaptiveSizePolicy::_debug_perturbation = false; 36 37 // The throughput goal is implemented as 38 // _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio)) 39 // gc_cost_ratio is the ratio 40 // application cost / gc cost 41 // For example a gc_cost_ratio of 4 translates into a 42 // throughput goal of .80 43 44 AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size, 45 size_t init_promo_size, 46 size_t init_survivor_size, 47 double gc_pause_goal_sec, 48 uint gc_cost_ratio) : 49 _eden_size(init_eden_size), 50 _promo_size(init_promo_size), 51 _survivor_size(init_survivor_size), 52 _gc_pause_goal_sec(gc_pause_goal_sec), 53 _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))), 54 _gc_overhead_limit_exceeded(false), 55 _print_gc_overhead_limit_would_be_exceeded(false), 56 _gc_overhead_limit_count(0), 57 _latest_minor_mutator_interval_seconds(0), 58 _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0), 59 _young_gen_change_for_minor_throughput(0), 60 _old_gen_change_for_major_throughput(0) { 61 assert(AdaptiveSizePolicyGCTimeLimitThreshold > 0, 62 "No opportunity to clear SoftReferences before GC overhead limit"); 63 _avg_minor_pause = 64 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding); 65 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 66 _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 67 _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 68 69 _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); 70 _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); 71 _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); 72 73 _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight, 74 SurvivorPadding); 75 _avg_pretenured = new AdaptivePaddedNoZeroDevAverage( 76 AdaptiveSizePolicyWeight, 77 SurvivorPadding); 78 79 _minor_pause_old_estimator = 80 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 81 _minor_pause_young_estimator = 82 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 83 _minor_collection_estimator = 84 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 85 _major_collection_estimator = 86 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 87 88 // Start the timers 89 _minor_timer.start(); 90 91 _young_gen_policy_is_ready = false; 92 } 93 94 // If the number of GC threads was set on the command line, 95 // use it. 96 // Else 97 // Calculate the number of GC threads based on the number of Java threads. 98 // Calculate the number of GC threads based on the size of the heap. 99 // Use the larger. 100 101 uint AdaptiveSizePolicy::calc_default_active_workers(uintx total_workers, 102 const uintx min_workers, 103 uintx active_workers, 104 uintx application_workers) { 105 // If the user has specifically set the number of 106 // GC threads, use them. 107 108 // If the user has turned off using a dynamic number of GC threads 109 // or the users has requested a specific number, set the active 110 // number of workers to all the workers. 111 112 uintx new_active_workers = total_workers; 113 uintx prev_active_workers = active_workers; 114 uintx active_workers_by_JT = 0; 115 uintx active_workers_by_heap_size = 0; 116 117 // Always use at least min_workers but use up to 118 // GCThreadsPerJavaThreads * application threads. 119 active_workers_by_JT = 120 MAX2((uintx) GCWorkersPerJavaThread * application_workers, 121 min_workers); 122 123 // Choose a number of GC threads based on the current size 124 // of the heap. This may be complicated because the size of 125 // the heap depends on factors such as the throughput goal. 126 // Still a large heap should be collected by more GC threads. 127 active_workers_by_heap_size = 128 MAX2((size_t) 2U, Universe::heap()->capacity() / HeapSizePerGCThread); 129 130 uintx max_active_workers = 131 MAX2(active_workers_by_JT, active_workers_by_heap_size); 132 133 new_active_workers = MIN2(max_active_workers, (uintx) total_workers); 134 135 // Increase GC workers instantly but decrease them more 136 // slowly. 137 if (new_active_workers < prev_active_workers) { 138 new_active_workers = 139 MAX2(min_workers, (prev_active_workers + new_active_workers) / 2); 140 } 141 142 // Check once more that the number of workers is within the limits. 143 assert(min_workers <= total_workers, "Minimum workers not consistent with total workers"); 144 assert(new_active_workers >= min_workers, "Minimum workers not observed"); 145 assert(new_active_workers <= total_workers, "Total workers not observed"); 146 147 if (ForceDynamicNumberOfGCThreads) { 148 // Assume this is debugging and jiggle the number of GC threads. 149 if (new_active_workers == prev_active_workers) { 150 if (new_active_workers < total_workers) { 151 new_active_workers++; 152 } else if (new_active_workers > min_workers) { 153 new_active_workers--; 154 } 155 } 156 if (new_active_workers == total_workers) { 157 if (_debug_perturbation) { 158 new_active_workers = min_workers; 159 } 160 _debug_perturbation = !_debug_perturbation; 161 } 162 assert((new_active_workers <= ParallelGCThreads) && 163 (new_active_workers >= min_workers), 164 "Jiggled active workers too much"); 165 } 166 167 log_trace(gc, task)("GCTaskManager::calc_default_active_workers() : " 168 "active_workers(): " UINTX_FORMAT " new_active_workers: " UINTX_FORMAT " " 169 "prev_active_workers: " UINTX_FORMAT "\n" 170 " active_workers_by_JT: " UINTX_FORMAT " active_workers_by_heap_size: " UINTX_FORMAT, 171 active_workers, new_active_workers, prev_active_workers, 172 active_workers_by_JT, active_workers_by_heap_size); 173 assert(new_active_workers > 0, "Always need at least 1"); 174 return new_active_workers; 175 } 176 177 uint AdaptiveSizePolicy::calc_active_workers(uintx total_workers, 178 uintx active_workers, 179 uintx application_workers) { 180 // If the user has specifically set the number of 181 // GC threads, use them. 182 183 // If the user has turned off using a dynamic number of GC threads 184 // or the users has requested a specific number, set the active 185 // number of workers to all the workers. 186 187 uint new_active_workers; 188 if (!UseDynamicNumberOfGCThreads || 189 (!FLAG_IS_DEFAULT(ParallelGCThreads) && !ForceDynamicNumberOfGCThreads)) { 190 new_active_workers = total_workers; 191 } else { 192 uintx min_workers = (total_workers == 1) ? 1 : 2; 193 new_active_workers = calc_default_active_workers(total_workers, 194 min_workers, 195 active_workers, 196 application_workers); 197 } 198 assert(new_active_workers > 0, "Always need at least 1"); 199 return new_active_workers; 200 } 201 202 uint AdaptiveSizePolicy::calc_active_conc_workers(uintx total_workers, 203 uintx active_workers, 204 uintx application_workers) { 205 if (!UseDynamicNumberOfGCThreads || 206 (!FLAG_IS_DEFAULT(ConcGCThreads) && !ForceDynamicNumberOfGCThreads)) { 207 return ConcGCThreads; 208 } else { 209 uint no_of_gc_threads = calc_default_active_workers(total_workers, 210 1, /* Minimum number of workers */ 211 active_workers, 212 application_workers); 213 return no_of_gc_threads; 214 } 215 } 216 217 bool AdaptiveSizePolicy::tenuring_threshold_change() const { 218 return decrement_tenuring_threshold_for_gc_cost() || 219 increment_tenuring_threshold_for_gc_cost() || 220 decrement_tenuring_threshold_for_survivor_limit(); 221 } 222 223 void AdaptiveSizePolicy::minor_collection_begin() { 224 // Update the interval time 225 _minor_timer.stop(); 226 // Save most recent collection time 227 _latest_minor_mutator_interval_seconds = _minor_timer.seconds(); 228 _minor_timer.reset(); 229 _minor_timer.start(); 230 } 231 232 void AdaptiveSizePolicy::update_minor_pause_young_estimator( 233 double minor_pause_in_ms) { 234 double eden_size_in_mbytes = ((double)_eden_size)/((double)M); 235 _minor_pause_young_estimator->update(eden_size_in_mbytes, 236 minor_pause_in_ms); 237 } 238 239 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) { 240 // Update the pause time. 241 _minor_timer.stop(); 242 243 if (!GCCause::is_user_requested_gc(gc_cause) || 244 UseAdaptiveSizePolicyWithSystemGC) { 245 double minor_pause_in_seconds = _minor_timer.seconds(); 246 double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS; 247 248 // Sample for performance counter 249 _avg_minor_pause->sample(minor_pause_in_seconds); 250 251 // Cost of collection (unit-less) 252 double collection_cost = 0.0; 253 if ((_latest_minor_mutator_interval_seconds > 0.0) && 254 (minor_pause_in_seconds > 0.0)) { 255 double interval_in_seconds = 256 _latest_minor_mutator_interval_seconds + minor_pause_in_seconds; 257 collection_cost = 258 minor_pause_in_seconds / interval_in_seconds; 259 _avg_minor_gc_cost->sample(collection_cost); 260 // Sample for performance counter 261 _avg_minor_interval->sample(interval_in_seconds); 262 } 263 264 // The policy does not have enough data until at least some 265 // young collections have been done. 266 _young_gen_policy_is_ready = 267 (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold); 268 269 // Calculate variables used to estimate pause time vs. gen sizes 270 double eden_size_in_mbytes = ((double)_eden_size) / ((double)M); 271 update_minor_pause_young_estimator(minor_pause_in_ms); 272 update_minor_pause_old_estimator(minor_pause_in_ms); 273 274 log_trace(gc, ergo)("AdaptiveSizePolicy::minor_collection_end: minor gc cost: %f average: %f", 275 collection_cost, _avg_minor_gc_cost->average()); 276 log_trace(gc, ergo)(" minor pause: %f minor period %f", 277 minor_pause_in_ms, _latest_minor_mutator_interval_seconds * MILLIUNITS); 278 279 // Calculate variable used to estimate collection cost vs. gen sizes 280 assert(collection_cost >= 0.0, "Expected to be non-negative"); 281 _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost); 282 } 283 284 // Interval times use this timer to measure the mutator time. 285 // Reset the timer after the GC pause. 286 _minor_timer.reset(); 287 _minor_timer.start(); 288 } 289 290 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden, uint percent_change) { 291 size_t eden_heap_delta; 292 eden_heap_delta = cur_eden / 100 * percent_change; 293 return eden_heap_delta; 294 } 295 296 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) { 297 return eden_increment(cur_eden, YoungGenerationSizeIncrement); 298 } 299 300 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) { 301 size_t eden_heap_delta = eden_increment(cur_eden) / 302 AdaptiveSizeDecrementScaleFactor; 303 return eden_heap_delta; 304 } 305 306 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo, uint percent_change) { 307 size_t promo_heap_delta; 308 promo_heap_delta = cur_promo / 100 * percent_change; 309 return promo_heap_delta; 310 } 311 312 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) { 313 return promo_increment(cur_promo, TenuredGenerationSizeIncrement); 314 } 315 316 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) { 317 size_t promo_heap_delta = promo_increment(cur_promo); 318 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor; 319 return promo_heap_delta; 320 } 321 322 double AdaptiveSizePolicy::time_since_major_gc() const { 323 _major_timer.stop(); 324 double result = _major_timer.seconds(); 325 _major_timer.start(); 326 return result; 327 } 328 329 // Linear decay of major gc cost 330 double AdaptiveSizePolicy::decaying_major_gc_cost() const { 331 double major_interval = major_gc_interval_average_for_decay(); 332 double major_gc_cost_average = major_gc_cost(); 333 double decayed_major_gc_cost = major_gc_cost_average; 334 if(time_since_major_gc() > 0.0) { 335 decayed_major_gc_cost = major_gc_cost() * 336 (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval) 337 / time_since_major_gc(); 338 } 339 340 // The decayed cost should always be smaller than the 341 // average cost but the vagaries of finite arithmetic could 342 // produce a larger value in decayed_major_gc_cost so protect 343 // against that. 344 return MIN2(major_gc_cost_average, decayed_major_gc_cost); 345 } 346 347 // Use a value of the major gc cost that has been decayed 348 // by the factor 349 // 350 // average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale / 351 // time-since-last-major-gc 352 // 353 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale 354 // is less than time-since-last-major-gc. 355 // 356 // In cases where there are initial major gc's that 357 // are of a relatively high cost but no later major 358 // gc's, the total gc cost can remain high because 359 // the major gc cost remains unchanged (since there are no major 360 // gc's). In such a situation the value of the unchanging 361 // major gc cost can keep the mutator throughput below 362 // the goal when in fact the major gc cost is becoming diminishingly 363 // small. Use the decaying gc cost only to decide whether to 364 // adjust for throughput. Using it also to determine the adjustment 365 // to be made for throughput also seems reasonable but there is 366 // no test case to use to decide if it is the right thing to do 367 // don't do it yet. 368 369 double AdaptiveSizePolicy::decaying_gc_cost() const { 370 double decayed_major_gc_cost = major_gc_cost(); 371 double avg_major_interval = major_gc_interval_average_for_decay(); 372 if (UseAdaptiveSizeDecayMajorGCCost && 373 (AdaptiveSizeMajorGCDecayTimeScale > 0) && 374 (avg_major_interval > 0.00)) { 375 double time_since_last_major_gc = time_since_major_gc(); 376 377 // Decay the major gc cost? 378 if (time_since_last_major_gc > 379 ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) { 380 381 // Decay using the time-since-last-major-gc 382 decayed_major_gc_cost = decaying_major_gc_cost(); 383 log_trace(gc, ergo)("decaying_gc_cost: major interval average: %f time since last major gc: %f", 384 avg_major_interval, time_since_last_major_gc); 385 log_trace(gc, ergo)(" major gc cost: %f decayed major gc cost: %f", 386 major_gc_cost(), decayed_major_gc_cost); 387 } 388 } 389 double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost()); 390 return result; 391 } 392 393 394 void AdaptiveSizePolicy::clear_generation_free_space_flags() { 395 set_change_young_gen_for_min_pauses(0); 396 set_change_old_gen_for_maj_pauses(0); 397 398 set_change_old_gen_for_throughput(0); 399 set_change_young_gen_for_throughput(0); 400 set_decrease_for_footprint(0); 401 set_decide_at_full_gc(0); 402 } 403 404 void AdaptiveSizePolicy::check_gc_overhead_limit( 405 size_t young_live, 406 size_t eden_live, 407 size_t max_old_gen_size, 408 size_t max_eden_size, 409 bool is_full_gc, 410 GCCause::Cause gc_cause, 411 CollectorPolicy* collector_policy) { 412 413 // Ignore explicit GC's. Exiting here does not set the flag and 414 // does not reset the count. Updating of the averages for system 415 // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC. 416 if (GCCause::is_user_requested_gc(gc_cause) || 417 GCCause::is_serviceability_requested_gc(gc_cause)) { 418 return; 419 } 420 // eden_limit is the upper limit on the size of eden based on 421 // the maximum size of the young generation and the sizes 422 // of the survivor space. 423 // The question being asked is whether the gc costs are high 424 // and the space being recovered by a collection is low. 425 // free_in_young_gen is the free space in the young generation 426 // after a collection and promo_live is the free space in the old 427 // generation after a collection. 428 // 429 // Use the minimum of the current value of the live in the 430 // young gen or the average of the live in the young gen. 431 // If the current value drops quickly, that should be taken 432 // into account (i.e., don't trigger if the amount of free 433 // space has suddenly jumped up). If the current is much 434 // higher than the average, use the average since it represents 435 // the longer term behavior. 436 const size_t live_in_eden = 437 MIN2(eden_live, (size_t) avg_eden_live()->average()); 438 const size_t free_in_eden = max_eden_size > live_in_eden ? 439 max_eden_size - live_in_eden : 0; 440 const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average()); 441 const size_t total_free_limit = free_in_old_gen + free_in_eden; 442 const size_t total_mem = max_old_gen_size + max_eden_size; 443 const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0); 444 const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0); 445 const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0); 446 const double gc_cost_limit = GCTimeLimit/100.0; 447 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average()); 448 // But don't force a promo size below the current promo size. Otherwise, 449 // the promo size will shrink for no good reason. 450 promo_limit = MAX2(promo_limit, _promo_size); 451 452 453 log_trace(gc, ergo)( 454 "PSAdaptiveSizePolicy::check_gc_overhead_limit:" 455 " promo_limit: " SIZE_FORMAT 456 " max_eden_size: " SIZE_FORMAT 457 " total_free_limit: " SIZE_FORMAT 458 " max_old_gen_size: " SIZE_FORMAT 459 " max_eden_size: " SIZE_FORMAT 460 " mem_free_limit: " SIZE_FORMAT, 461 promo_limit, max_eden_size, total_free_limit, 462 max_old_gen_size, max_eden_size, 463 (size_t) mem_free_limit); 464 465 bool print_gc_overhead_limit_would_be_exceeded = false; 466 if (is_full_gc) { 467 if (gc_cost() > gc_cost_limit && 468 free_in_old_gen < (size_t) mem_free_old_limit && 469 free_in_eden < (size_t) mem_free_eden_limit) { 470 // Collections, on average, are taking too much time, and 471 // gc_cost() > gc_cost_limit 472 // we have too little space available after a full gc. 473 // total_free_limit < mem_free_limit 474 // where 475 // total_free_limit is the free space available in 476 // both generations 477 // total_mem is the total space available for allocation 478 // in both generations (survivor spaces are not included 479 // just as they are not included in eden_limit). 480 // mem_free_limit is a fraction of total_mem judged to be an 481 // acceptable amount that is still unused. 482 // The heap can ask for the value of this variable when deciding 483 // whether to thrown an OutOfMemory error. 484 // Note that the gc time limit test only works for the collections 485 // of the young gen + tenured gen and not for collections of the 486 // permanent gen. That is because the calculation of the space 487 // freed by the collection is the free space in the young gen + 488 // tenured gen. 489 // At this point the GC overhead limit is being exceeded. 490 inc_gc_overhead_limit_count(); 491 if (UseGCOverheadLimit) { 492 if (gc_overhead_limit_count() >= 493 AdaptiveSizePolicyGCTimeLimitThreshold){ 494 // All conditions have been met for throwing an out-of-memory 495 set_gc_overhead_limit_exceeded(true); 496 // Avoid consecutive OOM due to the gc time limit by resetting 497 // the counter. 498 reset_gc_overhead_limit_count(); 499 } else { 500 // The required consecutive collections which exceed the 501 // GC time limit may or may not have been reached. We 502 // are approaching that condition and so as not to 503 // throw an out-of-memory before all SoftRef's have been 504 // cleared, set _should_clear_all_soft_refs in CollectorPolicy. 505 // The clearing will be done on the next GC. 506 bool near_limit = gc_overhead_limit_near(); 507 if (near_limit) { 508 collector_policy->set_should_clear_all_soft_refs(true); 509 log_trace(gc, ergo)("Nearing GC overhead limit, will be clearing all SoftReference"); 510 } 511 } 512 } 513 // Set this even when the overhead limit will not 514 // cause an out-of-memory. Diagnostic message indicating 515 // that the overhead limit is being exceeded is sometimes 516 // printed. 517 print_gc_overhead_limit_would_be_exceeded = true; 518 519 } else { 520 // Did not exceed overhead limits 521 reset_gc_overhead_limit_count(); 522 } 523 } 524 525 if (UseGCOverheadLimit) { 526 if (gc_overhead_limit_exceeded()) { 527 log_trace(gc, ergo)("GC is exceeding overhead limit of " UINTX_FORMAT "%%", GCTimeLimit); 528 reset_gc_overhead_limit_count(); 529 } else if (print_gc_overhead_limit_would_be_exceeded) { 530 assert(gc_overhead_limit_count() > 0, "Should not be printing"); 531 log_trace(gc, ergo)("GC would exceed overhead limit of " UINTX_FORMAT "%% %d consecutive time(s)", 532 GCTimeLimit, gc_overhead_limit_count()); 533 } 534 } 535 } 536 // Printing 537 538 bool AdaptiveSizePolicy::print() const { 539 assert(UseAdaptiveSizePolicy, "UseAdaptiveSizePolicy need to be enabled."); 540 541 if (!log_is_enabled(Debug, gc, ergo)) { 542 return false; 543 } 544 545 // Print goal for which action is needed. 546 char* action = NULL; 547 bool change_for_pause = false; 548 if ((change_old_gen_for_maj_pauses() == 549 decrease_old_gen_for_maj_pauses_true) || 550 (change_young_gen_for_min_pauses() == 551 decrease_young_gen_for_min_pauses_true)) { 552 action = (char*) " *** pause time goal ***"; 553 change_for_pause = true; 554 } else if ((change_old_gen_for_throughput() == 555 increase_old_gen_for_throughput_true) || 556 (change_young_gen_for_throughput() == 557 increase_young_gen_for_througput_true)) { 558 action = (char*) " *** throughput goal ***"; 559 } else if (decrease_for_footprint()) { 560 action = (char*) " *** reduced footprint ***"; 561 } else { 562 // No actions were taken. This can legitimately be the 563 // situation if not enough data has been gathered to make 564 // decisions. 565 return false; 566 } 567 568 // Pauses 569 // Currently the size of the old gen is only adjusted to 570 // change the major pause times. 571 char* young_gen_action = NULL; 572 char* tenured_gen_action = NULL; 573 574 char* shrink_msg = (char*) "(attempted to shrink)"; 575 char* grow_msg = (char*) "(attempted to grow)"; 576 char* no_change_msg = (char*) "(no change)"; 577 if (change_young_gen_for_min_pauses() == 578 decrease_young_gen_for_min_pauses_true) { 579 young_gen_action = shrink_msg; 580 } else if (change_for_pause) { 581 young_gen_action = no_change_msg; 582 } 583 584 if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) { 585 tenured_gen_action = shrink_msg; 586 } else if (change_for_pause) { 587 tenured_gen_action = no_change_msg; 588 } 589 590 // Throughput 591 if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) { 592 assert(change_young_gen_for_throughput() == 593 increase_young_gen_for_througput_true, 594 "Both generations should be growing"); 595 young_gen_action = grow_msg; 596 tenured_gen_action = grow_msg; 597 } else if (change_young_gen_for_throughput() == 598 increase_young_gen_for_througput_true) { 599 // Only the young generation may grow at start up (before 600 // enough full collections have been done to grow the old generation). 601 young_gen_action = grow_msg; 602 tenured_gen_action = no_change_msg; 603 } 604 605 // Minimum footprint 606 if (decrease_for_footprint() != 0) { 607 young_gen_action = shrink_msg; 608 tenured_gen_action = shrink_msg; 609 } 610 611 log_debug(gc, ergo)("UseAdaptiveSizePolicy actions to meet %s", action); 612 log_debug(gc, ergo)(" GC overhead (%%)"); 613 log_debug(gc, ergo)(" Young generation: %7.2f\t %s", 614 100.0 * avg_minor_gc_cost()->average(), young_gen_action); 615 log_debug(gc, ergo)(" Tenured generation: %7.2f\t %s", 616 100.0 * avg_major_gc_cost()->average(), tenured_gen_action); 617 return true; 618 } 619 620 void AdaptiveSizePolicy::print_tenuring_threshold( uint new_tenuring_threshold_arg) const { 621 // Tenuring threshold 622 if (decrement_tenuring_threshold_for_survivor_limit()) { 623 log_debug(gc, ergo)("Tenuring threshold: (attempted to decrease to avoid survivor space overflow) = %u", new_tenuring_threshold_arg); 624 } else if (decrement_tenuring_threshold_for_gc_cost()) { 625 log_debug(gc, ergo)("Tenuring threshold: (attempted to decrease to balance GC costs) = %u", new_tenuring_threshold_arg); 626 } else if (increment_tenuring_threshold_for_gc_cost()) { 627 log_debug(gc, ergo)("Tenuring threshold: (attempted to increase to balance GC costs) = %u", new_tenuring_threshold_arg); 628 } else { 629 assert(!tenuring_threshold_change(), "(no change was attempted)"); 630 } 631 }