1 /* 2 * Copyright (c) 2002, 2013, 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_implementation/parallelScavenge/generationSizer.hpp" 27 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 28 #include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp" 29 #include "gc_implementation/parallelScavenge/psScavenge.hpp" 30 #include "gc_implementation/shared/gcPolicyCounters.hpp" 31 #include "gc_interface/gcCause.hpp" 32 #include "memory/collectorPolicy.hpp" 33 #include "runtime/timer.hpp" 34 #include "utilities/top.hpp" 35 36 #include <math.h> 37 38 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size, 39 size_t init_promo_size, 40 size_t init_survivor_size, 41 size_t intra_generation_alignment, 42 double gc_pause_goal_sec, 43 double gc_minor_pause_goal_sec, 44 uint gc_cost_ratio) : 45 AdaptiveSizePolicy(init_eden_size, 46 init_promo_size, 47 init_survivor_size, 48 gc_pause_goal_sec, 49 gc_cost_ratio), 50 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin/ 51 100.0), 52 _intra_generation_alignment(intra_generation_alignment), 53 _live_at_last_full_gc(init_promo_size), 54 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec), 55 _latest_major_mutator_interval_seconds(0), 56 _young_gen_change_for_major_pause_count(0) 57 { 58 // Sizing policy statistics 59 _avg_major_pause = 60 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding); 61 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 62 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 63 64 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); 65 _major_pause_old_estimator = 66 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 67 _major_pause_young_estimator = 68 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 69 _major_collection_estimator = 70 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 71 72 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement; 73 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement; 74 75 // Start the timers 76 _major_timer.start(); 77 78 _old_gen_policy_is_ready = false; 79 } 80 81 void PSAdaptiveSizePolicy::major_collection_begin() { 82 // Update the interval time 83 _major_timer.stop(); 84 // Save most recent collection time 85 _latest_major_mutator_interval_seconds = _major_timer.seconds(); 86 _major_timer.reset(); 87 _major_timer.start(); 88 } 89 90 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator( 91 double minor_pause_in_ms) { 92 double promo_size_in_mbytes = ((double)_promo_size)/((double)M); 93 _minor_pause_old_estimator->update(promo_size_in_mbytes, 94 minor_pause_in_ms); 95 } 96 97 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live, 98 GCCause::Cause gc_cause) { 99 // Update the pause time. 100 _major_timer.stop(); 101 102 if (gc_cause != GCCause::_java_lang_system_gc || 103 UseAdaptiveSizePolicyWithSystemGC) { 104 double major_pause_in_seconds = _major_timer.seconds(); 105 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS; 106 107 // Sample for performance counter 108 _avg_major_pause->sample(major_pause_in_seconds); 109 110 // Cost of collection (unit-less) 111 double collection_cost = 0.0; 112 if ((_latest_major_mutator_interval_seconds > 0.0) && 113 (major_pause_in_seconds > 0.0)) { 114 double interval_in_seconds = 115 _latest_major_mutator_interval_seconds + major_pause_in_seconds; 116 collection_cost = 117 major_pause_in_seconds / interval_in_seconds; 118 avg_major_gc_cost()->sample(collection_cost); 119 120 // Sample for performance counter 121 _avg_major_interval->sample(interval_in_seconds); 122 } 123 124 // Calculate variables used to estimate pause time vs. gen sizes 125 double eden_size_in_mbytes = ((double)_eden_size)/((double)M); 126 double promo_size_in_mbytes = ((double)_promo_size)/((double)M); 127 _major_pause_old_estimator->update(promo_size_in_mbytes, 128 major_pause_in_ms); 129 _major_pause_young_estimator->update(eden_size_in_mbytes, 130 major_pause_in_ms); 131 132 if (PrintAdaptiveSizePolicy && Verbose) { 133 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: " 134 "major gc cost: %f average: %f", collection_cost, 135 avg_major_gc_cost()->average()); 136 gclog_or_tty->print_cr(" major pause: %f major period %f", 137 major_pause_in_ms, 138 _latest_major_mutator_interval_seconds * MILLIUNITS); 139 } 140 141 // Calculate variable used to estimate collection cost vs. gen sizes 142 assert(collection_cost >= 0.0, "Expected to be non-negative"); 143 _major_collection_estimator->update(promo_size_in_mbytes, 144 collection_cost); 145 } 146 147 // Update the amount live at the end of a full GC 148 _live_at_last_full_gc = amount_live; 149 150 // The policy does not have enough data until at least some major collections 151 // have been done. 152 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) { 153 _old_gen_policy_is_ready = true; 154 } 155 156 // Interval times use this timer to measure the interval that 157 // the mutator runs. Reset after the GC pause has been measured. 158 _major_timer.reset(); 159 _major_timer.start(); 160 } 161 162 // If the remaining free space in the old generation is less that 163 // that expected to be needed by the next collection, do a full 164 // collection now. 165 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) { 166 167 // A similar test is done in the scavenge's should_attempt_scavenge(). If 168 // this is changed, decide if that test should also be changed. 169 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes; 170 if (PrintGCDetails && Verbose) { 171 if (result) { 172 gclog_or_tty->print(" full after scavenge: "); 173 } else { 174 gclog_or_tty->print(" no full after scavenge: "); 175 } 176 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 177 " padded_average_promoted " SIZE_FORMAT 178 " free in old gen " SIZE_FORMAT, 179 (size_t) average_promoted_in_bytes(), 180 (size_t) padded_average_promoted_in_bytes(), 181 old_free_in_bytes); 182 } 183 return result; 184 } 185 186 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() { 187 188 AdaptiveSizePolicy::clear_generation_free_space_flags(); 189 190 set_change_old_gen_for_min_pauses(0); 191 192 set_change_young_gen_for_maj_pauses(0); 193 } 194 195 // If this is not a full GC, only test and modify the young generation. 196 197 void PSAdaptiveSizePolicy::compute_generations_free_space( 198 size_t young_live, 199 size_t eden_live, 200 size_t old_live, 201 size_t cur_eden, 202 size_t max_old_gen_size, 203 size_t max_eden_size, 204 bool is_full_gc) { 205 compute_eden_space_size(young_live, 206 eden_live, 207 cur_eden, 208 max_eden_size, 209 is_full_gc); 210 211 compute_old_gen_free_space(old_live, 212 cur_eden, 213 max_old_gen_size, 214 is_full_gc); 215 } 216 217 void PSAdaptiveSizePolicy::compute_eden_space_size( 218 size_t young_live, 219 size_t eden_live, 220 size_t cur_eden, 221 size_t max_eden_size, 222 bool is_full_gc) { 223 224 // Update statistics 225 // Time statistics are updated as we go, update footprint stats here 226 _avg_base_footprint->sample(BaseFootPrintEstimate); 227 avg_young_live()->sample(young_live); 228 avg_eden_live()->sample(eden_live); 229 230 // This code used to return if the policy was not ready , i.e., 231 // policy_is_ready() returning false. The intent was that 232 // decisions below needed major collection times and so could 233 // not be made before two major collections. A consequence was 234 // adjustments to the young generation were not done until after 235 // two major collections even if the minor collections times 236 // exceeded the requested goals. Now let the young generation 237 // adjust for the minor collection times. Major collection times 238 // will be zero for the first collection and will naturally be 239 // ignored. Tenured generation adjustments are only made at the 240 // full collections so until the second major collection has 241 // been reached, no tenured generation adjustments will be made. 242 243 // Until we know better, desired promotion size uses the last calculation 244 size_t desired_promo_size = _promo_size; 245 246 // Start eden at the current value. The desired value that is stored 247 // in _eden_size is not bounded by constraints of the heap and can 248 // run away. 249 // 250 // As expected setting desired_eden_size to the current 251 // value of desired_eden_size as a starting point 252 // caused desired_eden_size to grow way too large and caused 253 // an overflow down stream. It may have improved performance in 254 // some case but is dangerous. 255 size_t desired_eden_size = cur_eden; 256 257 // Cache some values. There's a bit of work getting these, so 258 // we might save a little time. 259 const double major_cost = major_gc_cost(); 260 const double minor_cost = minor_gc_cost(); 261 262 // This method sets the desired eden size. That plus the 263 // desired survivor space sizes sets the desired young generation 264 // size. This methods does not know what the desired survivor 265 // size is but expects that other policy will attempt to make 266 // the survivor sizes compatible with the live data in the 267 // young generation. This limit is an estimate of the space left 268 // in the young generation after the survivor spaces have been 269 // subtracted out. 270 size_t eden_limit = max_eden_size; 271 272 const double gc_cost_limit = GCTimeLimit/100.0; 273 274 // Which way should we go? 275 // if pause requirement is not met 276 // adjust size of any generation with average paus exceeding 277 // the pause limit. Adjust one pause at a time (the larger) 278 // and only make adjustments for the major pause at full collections. 279 // else if throughput requirement not met 280 // adjust the size of the generation with larger gc time. Only 281 // adjust one generation at a time. 282 // else 283 // adjust down the total heap size. Adjust down the larger of the 284 // generations. 285 286 // Add some checks for a threshold for a change. For example, 287 // a change less than the necessary alignment is probably not worth 288 // attempting. 289 290 291 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || 292 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { 293 // 294 // Check pauses 295 // 296 // Make changes only to affect one of the pauses (the larger) 297 // at a time. 298 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 299 300 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) { 301 // Adjust only for the minor pause time goal 302 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size); 303 304 } else if(adjusted_mutator_cost() < _throughput_goal) { 305 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. 306 // This sometimes resulted in skipping to the minimize footprint 307 // code. Change this to try and reduce GC time if mutator time is 308 // negative for whatever reason. Or for future consideration, 309 // bail out of the code if mutator time is negative. 310 // 311 // Throughput 312 // 313 assert(major_cost >= 0.0, "major cost is < 0.0"); 314 assert(minor_cost >= 0.0, "minor cost is < 0.0"); 315 // Try to reduce the GC times. 316 adjust_eden_for_throughput(is_full_gc, &desired_eden_size); 317 318 } else { 319 320 // Be conservative about reducing the footprint. 321 // Do a minimum number of major collections first. 322 // Have reasonable averages for major and minor collections costs. 323 if (UseAdaptiveSizePolicyFootprintGoal && 324 young_gen_policy_is_ready() && 325 avg_major_gc_cost()->average() >= 0.0 && 326 avg_minor_gc_cost()->average() >= 0.0) { 327 size_t desired_sum = desired_eden_size + desired_promo_size; 328 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum); 329 } 330 } 331 332 // Note we make the same tests as in the code block below; the code 333 // seems a little easier to read with the printing in another block. 334 if (PrintAdaptiveSizePolicy) { 335 if (desired_eden_size > eden_limit) { 336 gclog_or_tty->print_cr( 337 "PSAdaptiveSizePolicy::compute_eden_space_size limits:" 338 " desired_eden_size: " SIZE_FORMAT 339 " old_eden_size: " SIZE_FORMAT 340 " eden_limit: " SIZE_FORMAT 341 " cur_eden: " SIZE_FORMAT 342 " max_eden_size: " SIZE_FORMAT 343 " avg_young_live: " SIZE_FORMAT, 344 desired_eden_size, _eden_size, eden_limit, cur_eden, 345 max_eden_size, (size_t)avg_young_live()->average()); 346 } 347 if (gc_cost() > gc_cost_limit) { 348 gclog_or_tty->print_cr( 349 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit" 350 " gc_cost: %f " 351 " GCTimeLimit: %d", 352 gc_cost(), GCTimeLimit); 353 } 354 } 355 356 // Align everything and make a final limit check 357 const size_t alignment = _intra_generation_alignment; 358 desired_eden_size = align_size_up(desired_eden_size, alignment); 359 desired_eden_size = MAX2(desired_eden_size, alignment); 360 361 eden_limit = align_size_down(eden_limit, alignment); 362 363 // And one last limit check, now that we've aligned things. 364 if (desired_eden_size > eden_limit) { 365 // If the policy says to get a larger eden but 366 // is hitting the limit, don't decrease eden. 367 // This can lead to a general drifting down of the 368 // eden size. Let the tenuring calculation push more 369 // into the old gen. 370 desired_eden_size = MAX2(eden_limit, cur_eden); 371 } 372 373 if (PrintAdaptiveSizePolicy) { 374 // Timing stats 375 gclog_or_tty->print( 376 "PSAdaptiveSizePolicy::compute_eden_space_size: costs" 377 " minor_time: %f" 378 " major_cost: %f" 379 " mutator_cost: %f" 380 " throughput_goal: %f", 381 minor_gc_cost(), major_gc_cost(), mutator_cost(), 382 _throughput_goal); 383 384 // We give more details if Verbose is set 385 if (Verbose) { 386 gclog_or_tty->print( " minor_pause: %f" 387 " major_pause: %f" 388 " minor_interval: %f" 389 " major_interval: %f" 390 " pause_goal: %f", 391 _avg_minor_pause->padded_average(), 392 _avg_major_pause->padded_average(), 393 _avg_minor_interval->average(), 394 _avg_major_interval->average(), 395 gc_pause_goal_sec()); 396 } 397 398 // Footprint stats 399 gclog_or_tty->print( " live_space: " SIZE_FORMAT 400 " free_space: " SIZE_FORMAT, 401 live_space(), free_space()); 402 // More detail 403 if (Verbose) { 404 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT 405 " avg_young_live: " SIZE_FORMAT 406 " avg_old_live: " SIZE_FORMAT, 407 (size_t)_avg_base_footprint->average(), 408 (size_t)avg_young_live()->average(), 409 (size_t)avg_old_live()->average()); 410 } 411 412 // And finally, our old and new sizes. 413 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT 414 " desired_eden_size: " SIZE_FORMAT, 415 _eden_size, desired_eden_size); 416 gclog_or_tty->cr(); 417 } 418 419 set_eden_size(desired_eden_size); 420 } 421 422 void PSAdaptiveSizePolicy::compute_old_gen_free_space( 423 size_t old_live, 424 size_t cur_eden, 425 size_t max_old_gen_size, 426 bool is_full_gc) { 427 428 // Update statistics 429 // Time statistics are updated as we go, update footprint stats here 430 if (is_full_gc) { 431 // old_live is only accurate after a full gc 432 avg_old_live()->sample(old_live); 433 } 434 435 // This code used to return if the policy was not ready , i.e., 436 // policy_is_ready() returning false. The intent was that 437 // decisions below needed major collection times and so could 438 // not be made before two major collections. A consequence was 439 // adjustments to the young generation were not done until after 440 // two major collections even if the minor collections times 441 // exceeded the requested goals. Now let the young generation 442 // adjust for the minor collection times. Major collection times 443 // will be zero for the first collection and will naturally be 444 // ignored. Tenured generation adjustments are only made at the 445 // full collections so until the second major collection has 446 // been reached, no tenured generation adjustments will be made. 447 448 // Until we know better, desired promotion size uses the last calculation 449 size_t desired_promo_size = _promo_size; 450 451 // Start eden at the current value. The desired value that is stored 452 // in _eden_size is not bounded by constraints of the heap and can 453 // run away. 454 // 455 // As expected setting desired_eden_size to the current 456 // value of desired_eden_size as a starting point 457 // caused desired_eden_size to grow way too large and caused 458 // an overflow down stream. It may have improved performance in 459 // some case but is dangerous. 460 size_t desired_eden_size = cur_eden; 461 462 // Cache some values. There's a bit of work getting these, so 463 // we might save a little time. 464 const double major_cost = major_gc_cost(); 465 const double minor_cost = minor_gc_cost(); 466 467 // Limits on our growth 468 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average()); 469 470 // But don't force a promo size below the current promo size. Otherwise, 471 // the promo size will shrink for no good reason. 472 promo_limit = MAX2(promo_limit, _promo_size); 473 474 const double gc_cost_limit = GCTimeLimit/100.0; 475 476 // Which way should we go? 477 // if pause requirement is not met 478 // adjust size of any generation with average paus exceeding 479 // the pause limit. Adjust one pause at a time (the larger) 480 // and only make adjustments for the major pause at full collections. 481 // else if throughput requirement not met 482 // adjust the size of the generation with larger gc time. Only 483 // adjust one generation at a time. 484 // else 485 // adjust down the total heap size. Adjust down the larger of the 486 // generations. 487 488 // Add some checks for a threshhold for a change. For example, 489 // a change less than the necessary alignment is probably not worth 490 // attempting. 491 492 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || 493 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { 494 // 495 // Check pauses 496 // 497 // Make changes only to affect one of the pauses (the larger) 498 // at a time. 499 if (is_full_gc) { 500 set_decide_at_full_gc(decide_at_full_gc_true); 501 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 502 } 503 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) { 504 // Adjust only for the minor pause time goal 505 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 506 } else if(adjusted_mutator_cost() < _throughput_goal) { 507 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. 508 // This sometimes resulted in skipping to the minimize footprint 509 // code. Change this to try and reduce GC time if mutator time is 510 // negative for whatever reason. Or for future consideration, 511 // bail out of the code if mutator time is negative. 512 // 513 // Throughput 514 // 515 assert(major_cost >= 0.0, "major cost is < 0.0"); 516 assert(minor_cost >= 0.0, "minor cost is < 0.0"); 517 // Try to reduce the GC times. 518 if (is_full_gc) { 519 set_decide_at_full_gc(decide_at_full_gc_true); 520 adjust_promo_for_throughput(is_full_gc, &desired_promo_size); 521 } 522 } else { 523 524 // Be conservative about reducing the footprint. 525 // Do a minimum number of major collections first. 526 // Have reasonable averages for major and minor collections costs. 527 if (UseAdaptiveSizePolicyFootprintGoal && 528 young_gen_policy_is_ready() && 529 avg_major_gc_cost()->average() >= 0.0 && 530 avg_minor_gc_cost()->average() >= 0.0) { 531 if (is_full_gc) { 532 set_decide_at_full_gc(decide_at_full_gc_true); 533 size_t desired_sum = desired_eden_size + desired_promo_size; 534 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum); 535 } 536 } 537 } 538 539 // Note we make the same tests as in the code block below; the code 540 // seems a little easier to read with the printing in another block. 541 if (PrintAdaptiveSizePolicy) { 542 if (desired_promo_size > promo_limit) { 543 // "free_in_old_gen" was the original value for used for promo_limit 544 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average()); 545 gclog_or_tty->print_cr( 546 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:" 547 " desired_promo_size: " SIZE_FORMAT 548 " promo_limit: " SIZE_FORMAT 549 " free_in_old_gen: " SIZE_FORMAT 550 " max_old_gen_size: " SIZE_FORMAT 551 " avg_old_live: " SIZE_FORMAT, 552 desired_promo_size, promo_limit, free_in_old_gen, 553 max_old_gen_size, (size_t) avg_old_live()->average()); 554 } 555 if (gc_cost() > gc_cost_limit) { 556 gclog_or_tty->print_cr( 557 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit" 558 " gc_cost: %f " 559 " GCTimeLimit: %d", 560 gc_cost(), GCTimeLimit); 561 } 562 } 563 564 // Align everything and make a final limit check 565 const size_t alignment = _intra_generation_alignment; 566 desired_promo_size = align_size_up(desired_promo_size, alignment); 567 desired_promo_size = MAX2(desired_promo_size, alignment); 568 569 promo_limit = align_size_down(promo_limit, alignment); 570 571 // And one last limit check, now that we've aligned things. 572 desired_promo_size = MIN2(desired_promo_size, promo_limit); 573 574 if (PrintAdaptiveSizePolicy) { 575 // Timing stats 576 gclog_or_tty->print( 577 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs" 578 " minor_time: %f" 579 " major_cost: %f" 580 " mutator_cost: %f" 581 " throughput_goal: %f", 582 minor_gc_cost(), major_gc_cost(), mutator_cost(), 583 _throughput_goal); 584 585 // We give more details if Verbose is set 586 if (Verbose) { 587 gclog_or_tty->print( " minor_pause: %f" 588 " major_pause: %f" 589 " minor_interval: %f" 590 " major_interval: %f" 591 " pause_goal: %f", 592 _avg_minor_pause->padded_average(), 593 _avg_major_pause->padded_average(), 594 _avg_minor_interval->average(), 595 _avg_major_interval->average(), 596 gc_pause_goal_sec()); 597 } 598 599 // Footprint stats 600 gclog_or_tty->print( " live_space: " SIZE_FORMAT 601 " free_space: " SIZE_FORMAT, 602 live_space(), free_space()); 603 // More detail 604 if (Verbose) { 605 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT 606 " avg_young_live: " SIZE_FORMAT 607 " avg_old_live: " SIZE_FORMAT, 608 (size_t)_avg_base_footprint->average(), 609 (size_t)avg_young_live()->average(), 610 (size_t)avg_old_live()->average()); 611 } 612 613 // And finally, our old and new sizes. 614 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT 615 " desired_promo_size: " SIZE_FORMAT, 616 _promo_size, desired_promo_size); 617 gclog_or_tty->cr(); 618 } 619 620 set_promo_size(desired_promo_size); 621 } 622 623 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) { 624 // Decay the supplemental increment? Decay the supplement growth 625 // factor even if it is not used. It is only meant to give a boost 626 // to the initial growth and if it is not used, then it was not 627 // needed. 628 if (is_full_gc) { 629 // Don't wait for the threshold value for the major collections. If 630 // here, the supplemental growth term was used and should decay. 631 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay) 632 == 0) { 633 _old_gen_size_increment_supplement = 634 _old_gen_size_increment_supplement >> 1; 635 } 636 } else { 637 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) && 638 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) { 639 _young_gen_size_increment_supplement = 640 _young_gen_size_increment_supplement >> 1; 641 } 642 } 643 } 644 645 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc, 646 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) { 647 648 if (PSAdjustTenuredGenForMinorPause) { 649 if (is_full_gc) { 650 set_decide_at_full_gc(decide_at_full_gc_true); 651 } 652 // If the desired eden size is as small as it will get, 653 // try to adjust the old gen size. 654 if (*desired_eden_size_ptr <= _intra_generation_alignment) { 655 // Vary the old gen size to reduce the young gen pause. This 656 // may not be a good idea. This is just a test. 657 if (minor_pause_old_estimator()->decrement_will_decrease()) { 658 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true); 659 *desired_promo_size_ptr = 660 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr); 661 } else { 662 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true); 663 size_t promo_heap_delta = 664 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 665 if ((*desired_promo_size_ptr + promo_heap_delta) > 666 *desired_promo_size_ptr) { 667 *desired_promo_size_ptr = 668 _promo_size + promo_heap_delta; 669 } 670 } 671 } 672 } 673 } 674 675 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc, 676 size_t* desired_eden_size_ptr) { 677 678 // Adjust the young generation size to reduce pause time of 679 // of collections. 680 // 681 // The AdaptiveSizePolicyInitializingSteps test is not used 682 // here. It has not seemed to be needed but perhaps should 683 // be added for consistency. 684 if (minor_pause_young_estimator()->decrement_will_decrease()) { 685 // reduce eden size 686 set_change_young_gen_for_min_pauses( 687 decrease_young_gen_for_min_pauses_true); 688 *desired_eden_size_ptr = *desired_eden_size_ptr - 689 eden_decrement_aligned_down(*desired_eden_size_ptr); 690 } else { 691 // EXPERIMENTAL ADJUSTMENT 692 // Only record that the estimator indicated such an action. 693 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta; 694 set_change_young_gen_for_min_pauses( 695 increase_young_gen_for_min_pauses_true); 696 } 697 } 698 699 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc, 700 size_t* desired_promo_size_ptr, 701 size_t* desired_eden_size_ptr) { 702 703 size_t promo_heap_delta = 0; 704 // Add some checks for a threshold for a change. For example, 705 // a change less than the required alignment is probably not worth 706 // attempting. 707 708 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) { 709 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr); 710 // major pause adjustments 711 } else if (is_full_gc) { 712 // Adjust for the major pause time only at full gc's because the 713 // affects of a change can only be seen at full gc's. 714 715 // Reduce old generation size to reduce pause? 716 if (major_pause_old_estimator()->decrement_will_decrease()) { 717 // reduce old generation size 718 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true); 719 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr); 720 *desired_promo_size_ptr = _promo_size - promo_heap_delta; 721 } else { 722 // EXPERIMENTAL ADJUSTMENT 723 // Only record that the estimator indicated such an action. 724 // *desired_promo_size_ptr = _promo_size + 725 // promo_increment_aligned_up(*desired_promo_size_ptr); 726 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true); 727 } 728 } 729 730 if (PrintAdaptiveSizePolicy && Verbose) { 731 gclog_or_tty->print_cr( 732 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time " 733 "adjusting gen sizes for major pause (avg %f goal %f). " 734 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT, 735 _avg_major_pause->average(), gc_pause_goal_sec(), 736 *desired_promo_size_ptr, promo_heap_delta); 737 } 738 } 739 740 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc, 741 size_t* desired_promo_size_ptr, 742 size_t* desired_eden_size_ptr) { 743 744 size_t eden_heap_delta = 0; 745 // Add some checks for a threshold for a change. For example, 746 // a change less than the required alignment is probably not worth 747 // attempting. 748 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) { 749 adjust_eden_for_minor_pause_time(is_full_gc, 750 desired_eden_size_ptr); 751 // major pause adjustments 752 } else if (is_full_gc) { 753 // Adjust for the major pause time only at full gc's because the 754 // affects of a change can only be seen at full gc's. 755 if (PSAdjustYoungGenForMajorPause) { 756 // If the promo size is at the minimum (i.e., the old gen 757 // size will not actually decrease), consider changing the 758 // young gen size. 759 if (*desired_promo_size_ptr < _intra_generation_alignment) { 760 // If increasing the young generation will decrease the old gen 761 // pause, do it. 762 // During startup there is noise in the statistics for deciding 763 // on whether to increase or decrease the young gen size. For 764 // some number of iterations, just try to increase the young 765 // gen size if the major pause is too long to try and establish 766 // good statistics for later decisions. 767 if (major_pause_young_estimator()->increment_will_decrease() || 768 (_young_gen_change_for_major_pause_count 769 <= AdaptiveSizePolicyInitializingSteps)) { 770 set_change_young_gen_for_maj_pauses( 771 increase_young_gen_for_maj_pauses_true); 772 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr); 773 *desired_eden_size_ptr = _eden_size + eden_heap_delta; 774 _young_gen_change_for_major_pause_count++; 775 } else { 776 // Record that decreasing the young gen size would decrease 777 // the major pause 778 set_change_young_gen_for_maj_pauses( 779 decrease_young_gen_for_maj_pauses_true); 780 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr); 781 *desired_eden_size_ptr = _eden_size - eden_heap_delta; 782 } 783 } 784 } 785 } 786 787 if (PrintAdaptiveSizePolicy && Verbose) { 788 gclog_or_tty->print_cr( 789 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time " 790 "adjusting gen sizes for major pause (avg %f goal %f). " 791 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT, 792 _avg_major_pause->average(), gc_pause_goal_sec(), 793 *desired_eden_size_ptr, eden_heap_delta); 794 } 795 } 796 797 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc, 798 size_t* desired_promo_size_ptr) { 799 800 // Add some checks for a threshold for a change. For example, 801 // a change less than the required alignment is probably not worth 802 // attempting. 803 804 if ((gc_cost() + mutator_cost()) == 0.0) { 805 return; 806 } 807 808 if (PrintAdaptiveSizePolicy && Verbose) { 809 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput(" 810 "is_full: %d, promo: " SIZE_FORMAT "): ", 811 is_full_gc, *desired_promo_size_ptr); 812 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f " 813 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost()); 814 } 815 816 // Tenured generation 817 if (is_full_gc) { 818 // Calculate the change to use for the tenured gen. 819 size_t scaled_promo_heap_delta = 0; 820 // Can the increment to the generation be scaled? 821 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) { 822 size_t promo_heap_delta = 823 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 824 double scale_by_ratio = major_gc_cost() / gc_cost(); 825 scaled_promo_heap_delta = 826 (size_t) (scale_by_ratio * (double) promo_heap_delta); 827 if (PrintAdaptiveSizePolicy && Verbose) { 828 gclog_or_tty->print_cr( 829 "Scaled tenured increment: " SIZE_FORMAT " by %f down to " 830 SIZE_FORMAT, 831 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta); 832 } 833 } else if (major_gc_cost() >= 0.0) { 834 // Scaling is not going to work. If the major gc time is the 835 // larger, give it a full increment. 836 if (major_gc_cost() >= minor_gc_cost()) { 837 scaled_promo_heap_delta = 838 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 839 } 840 } else { 841 // Don't expect to get here but it's ok if it does 842 // in the product build since the delta will be 0 843 // and nothing will change. 844 assert(false, "Unexpected value for gc costs"); 845 } 846 847 switch (AdaptiveSizeThroughPutPolicy) { 848 case 1: 849 // Early in the run the statistics might not be good. Until 850 // a specific number of collections have been, use the heuristic 851 // that a larger generation size means lower collection costs. 852 if (major_collection_estimator()->increment_will_decrease() || 853 (_old_gen_change_for_major_throughput 854 <= AdaptiveSizePolicyInitializingSteps)) { 855 // Increase tenured generation size to reduce major collection cost 856 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > 857 *desired_promo_size_ptr) { 858 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta; 859 } 860 set_change_old_gen_for_throughput( 861 increase_old_gen_for_throughput_true); 862 _old_gen_change_for_major_throughput++; 863 } else { 864 // EXPERIMENTAL ADJUSTMENT 865 // Record that decreasing the old gen size would decrease 866 // the major collection cost but don't do it. 867 // *desired_promo_size_ptr = _promo_size - 868 // promo_decrement_aligned_down(*desired_promo_size_ptr); 869 set_change_old_gen_for_throughput( 870 decrease_old_gen_for_throughput_true); 871 } 872 873 break; 874 default: 875 // Simplest strategy 876 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > 877 *desired_promo_size_ptr) { 878 *desired_promo_size_ptr = *desired_promo_size_ptr + 879 scaled_promo_heap_delta; 880 } 881 set_change_old_gen_for_throughput( 882 increase_old_gen_for_throughput_true); 883 _old_gen_change_for_major_throughput++; 884 } 885 886 if (PrintAdaptiveSizePolicy && Verbose) { 887 gclog_or_tty->print_cr( 888 "adjusting tenured gen for throughput (avg %f goal %f). " 889 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT , 890 mutator_cost(), _throughput_goal, 891 *desired_promo_size_ptr, scaled_promo_heap_delta); 892 } 893 } 894 } 895 896 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc, 897 size_t* desired_eden_size_ptr) { 898 899 // Add some checks for a threshold for a change. For example, 900 // a change less than the required alignment is probably not worth 901 // attempting. 902 903 if ((gc_cost() + mutator_cost()) == 0.0) { 904 return; 905 } 906 907 if (PrintAdaptiveSizePolicy && Verbose) { 908 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput(" 909 "is_full: %d, cur_eden: " SIZE_FORMAT "): ", 910 is_full_gc, *desired_eden_size_ptr); 911 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f " 912 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost()); 913 } 914 915 // Young generation 916 size_t scaled_eden_heap_delta = 0; 917 // Can the increment to the generation be scaled? 918 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) { 919 size_t eden_heap_delta = 920 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); 921 double scale_by_ratio = minor_gc_cost() / gc_cost(); 922 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong"); 923 scaled_eden_heap_delta = 924 (size_t) (scale_by_ratio * (double) eden_heap_delta); 925 if (PrintAdaptiveSizePolicy && Verbose) { 926 gclog_or_tty->print_cr( 927 "Scaled eden increment: " SIZE_FORMAT " by %f down to " 928 SIZE_FORMAT, 929 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta); 930 } 931 } else if (minor_gc_cost() >= 0.0) { 932 // Scaling is not going to work. If the minor gc time is the 933 // larger, give it a full increment. 934 if (minor_gc_cost() > major_gc_cost()) { 935 scaled_eden_heap_delta = 936 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); 937 } 938 } else { 939 // Don't expect to get here but it's ok if it does 940 // in the product build since the delta will be 0 941 // and nothing will change. 942 assert(false, "Unexpected value for gc costs"); 943 } 944 945 // Use a heuristic for some number of collections to give 946 // the averages time to settle down. 947 switch (AdaptiveSizeThroughPutPolicy) { 948 case 1: 949 if (minor_collection_estimator()->increment_will_decrease() || 950 (_young_gen_change_for_minor_throughput 951 <= AdaptiveSizePolicyInitializingSteps)) { 952 // Expand young generation size to reduce frequency of 953 // of collections. 954 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > 955 *desired_eden_size_ptr) { 956 *desired_eden_size_ptr = 957 *desired_eden_size_ptr + scaled_eden_heap_delta; 958 } 959 set_change_young_gen_for_throughput( 960 increase_young_gen_for_througput_true); 961 _young_gen_change_for_minor_throughput++; 962 } else { 963 // EXPERIMENTAL ADJUSTMENT 964 // Record that decreasing the young gen size would decrease 965 // the minor collection cost but don't do it. 966 // *desired_eden_size_ptr = _eden_size - 967 // eden_decrement_aligned_down(*desired_eden_size_ptr); 968 set_change_young_gen_for_throughput( 969 decrease_young_gen_for_througput_true); 970 } 971 break; 972 default: 973 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > 974 *desired_eden_size_ptr) { 975 *desired_eden_size_ptr = 976 *desired_eden_size_ptr + scaled_eden_heap_delta; 977 } 978 set_change_young_gen_for_throughput( 979 increase_young_gen_for_througput_true); 980 _young_gen_change_for_minor_throughput++; 981 } 982 983 if (PrintAdaptiveSizePolicy && Verbose) { 984 gclog_or_tty->print_cr( 985 "adjusting eden for throughput (avg %f goal %f). desired_eden_size " 986 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n", 987 mutator_cost(), _throughput_goal, 988 *desired_eden_size_ptr, scaled_eden_heap_delta); 989 } 990 } 991 992 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint( 993 size_t desired_promo_size, size_t desired_sum) { 994 assert(desired_promo_size <= desired_sum, "Inconsistent parameters"); 995 set_decrease_for_footprint(decrease_old_gen_for_footprint_true); 996 997 size_t change = promo_decrement(desired_promo_size); 998 change = scale_down(change, desired_promo_size, desired_sum); 999 1000 size_t reduced_size = desired_promo_size - change; 1001 1002 if (PrintAdaptiveSizePolicy && Verbose) { 1003 gclog_or_tty->print_cr( 1004 "AdaptiveSizePolicy::adjust_promo_for_footprint " 1005 "adjusting tenured gen for footprint. " 1006 "starting promo size " SIZE_FORMAT 1007 " reduced promo size " SIZE_FORMAT, 1008 " promo delta " SIZE_FORMAT, 1009 desired_promo_size, reduced_size, change ); 1010 } 1011 1012 assert(reduced_size <= desired_promo_size, "Inconsistent result"); 1013 return reduced_size; 1014 } 1015 1016 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint( 1017 size_t desired_eden_size, size_t desired_sum) { 1018 assert(desired_eden_size <= desired_sum, "Inconsistent parameters"); 1019 set_decrease_for_footprint(decrease_young_gen_for_footprint_true); 1020 1021 size_t change = eden_decrement(desired_eden_size); 1022 change = scale_down(change, desired_eden_size, desired_sum); 1023 1024 size_t reduced_size = desired_eden_size - change; 1025 1026 if (PrintAdaptiveSizePolicy && Verbose) { 1027 gclog_or_tty->print_cr( 1028 "AdaptiveSizePolicy::adjust_eden_for_footprint " 1029 "adjusting eden for footprint. " 1030 " starting eden size " SIZE_FORMAT 1031 " reduced eden size " SIZE_FORMAT 1032 " eden delta " SIZE_FORMAT, 1033 desired_eden_size, reduced_size, change); 1034 } 1035 1036 assert(reduced_size <= desired_eden_size, "Inconsistent result"); 1037 return reduced_size; 1038 } 1039 1040 // Scale down "change" by the factor 1041 // part / total 1042 // Don't align the results. 1043 1044 size_t PSAdaptiveSizePolicy::scale_down(size_t change, 1045 double part, 1046 double total) { 1047 assert(part <= total, "Inconsistent input"); 1048 size_t reduced_change = change; 1049 if (total > 0) { 1050 double fraction = part / total; 1051 reduced_change = (size_t) (fraction * (double) change); 1052 } 1053 assert(reduced_change <= change, "Inconsistent result"); 1054 return reduced_change; 1055 } 1056 1057 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden, 1058 uint percent_change) { 1059 size_t eden_heap_delta; 1060 eden_heap_delta = cur_eden / 100 * percent_change; 1061 return eden_heap_delta; 1062 } 1063 1064 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) { 1065 return eden_increment(cur_eden, YoungGenerationSizeIncrement); 1066 } 1067 1068 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) { 1069 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement); 1070 return align_size_up(result, _intra_generation_alignment); 1071 } 1072 1073 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) { 1074 size_t result = eden_increment(cur_eden); 1075 return align_size_down(result, _intra_generation_alignment); 1076 } 1077 1078 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up( 1079 size_t cur_eden) { 1080 size_t result = eden_increment(cur_eden, 1081 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement); 1082 return align_size_up(result, _intra_generation_alignment); 1083 } 1084 1085 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) { 1086 size_t eden_heap_delta = eden_decrement(cur_eden); 1087 return align_size_down(eden_heap_delta, _intra_generation_alignment); 1088 } 1089 1090 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) { 1091 size_t eden_heap_delta = eden_increment(cur_eden) / 1092 AdaptiveSizeDecrementScaleFactor; 1093 return eden_heap_delta; 1094 } 1095 1096 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo, 1097 uint percent_change) { 1098 size_t promo_heap_delta; 1099 promo_heap_delta = cur_promo / 100 * percent_change; 1100 return promo_heap_delta; 1101 } 1102 1103 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) { 1104 return promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1105 } 1106 1107 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) { 1108 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1109 return align_size_up(result, _intra_generation_alignment); 1110 } 1111 1112 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) { 1113 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1114 return align_size_down(result, _intra_generation_alignment); 1115 } 1116 1117 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up( 1118 size_t cur_promo) { 1119 size_t result = promo_increment(cur_promo, 1120 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement); 1121 return align_size_up(result, _intra_generation_alignment); 1122 } 1123 1124 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) { 1125 size_t promo_heap_delta = promo_decrement(cur_promo); 1126 return align_size_down(promo_heap_delta, _intra_generation_alignment); 1127 } 1128 1129 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) { 1130 size_t promo_heap_delta = promo_increment(cur_promo); 1131 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor; 1132 return promo_heap_delta; 1133 } 1134 1135 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold( 1136 bool is_survivor_overflow, 1137 uint tenuring_threshold, 1138 size_t survivor_limit) { 1139 assert(survivor_limit >= _intra_generation_alignment, 1140 "survivor_limit too small"); 1141 assert((size_t)align_size_down(survivor_limit, _intra_generation_alignment) 1142 == survivor_limit, "survivor_limit not aligned"); 1143 1144 // This method is called even if the tenuring threshold and survivor 1145 // spaces are not adjusted so that the averages are sampled above. 1146 if (!UsePSAdaptiveSurvivorSizePolicy || 1147 !young_gen_policy_is_ready()) { 1148 return tenuring_threshold; 1149 } 1150 1151 // We'll decide whether to increase or decrease the tenuring 1152 // threshold based partly on the newly computed survivor size 1153 // (if we hit the maximum limit allowed, we'll always choose to 1154 // decrement the threshold). 1155 bool incr_tenuring_threshold = false; 1156 bool decr_tenuring_threshold = false; 1157 1158 set_decrement_tenuring_threshold_for_gc_cost(false); 1159 set_increment_tenuring_threshold_for_gc_cost(false); 1160 set_decrement_tenuring_threshold_for_survivor_limit(false); 1161 1162 if (!is_survivor_overflow) { 1163 // Keep running averages on how much survived 1164 1165 // We use the tenuring threshold to equalize the cost of major 1166 // and minor collections. 1167 // ThresholdTolerance is used to indicate how sensitive the 1168 // tenuring threshold is to differences in cost betweent the 1169 // collection types. 1170 1171 // Get the times of interest. This involves a little work, so 1172 // we cache the values here. 1173 const double major_cost = major_gc_cost(); 1174 const double minor_cost = minor_gc_cost(); 1175 1176 if (minor_cost > major_cost * _threshold_tolerance_percent) { 1177 // Minor times are getting too long; lower the threshold so 1178 // less survives and more is promoted. 1179 decr_tenuring_threshold = true; 1180 set_decrement_tenuring_threshold_for_gc_cost(true); 1181 } else if (major_cost > minor_cost * _threshold_tolerance_percent) { 1182 // Major times are too long, so we want less promotion. 1183 incr_tenuring_threshold = true; 1184 set_increment_tenuring_threshold_for_gc_cost(true); 1185 } 1186 1187 } else { 1188 // Survivor space overflow occurred, so promoted and survived are 1189 // not accurate. We'll make our best guess by combining survived 1190 // and promoted and count them as survivors. 1191 // 1192 // We'll lower the tenuring threshold to see if we can correct 1193 // things. Also, set the survivor size conservatively. We're 1194 // trying to avoid many overflows from occurring if defnew size 1195 // is just too small. 1196 1197 decr_tenuring_threshold = true; 1198 } 1199 1200 // The padded average also maintains a deviation from the average; 1201 // we use this to see how good of an estimate we have of what survived. 1202 // We're trying to pad the survivor size as little as possible without 1203 // overflowing the survivor spaces. 1204 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(), 1205 _intra_generation_alignment); 1206 target_size = MAX2(target_size, _intra_generation_alignment); 1207 1208 if (target_size > survivor_limit) { 1209 // Target size is bigger than we can handle. Let's also reduce 1210 // the tenuring threshold. 1211 target_size = survivor_limit; 1212 decr_tenuring_threshold = true; 1213 set_decrement_tenuring_threshold_for_survivor_limit(true); 1214 } 1215 1216 // Finally, increment or decrement the tenuring threshold, as decided above. 1217 // We test for decrementing first, as we might have hit the target size 1218 // limit. 1219 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { 1220 if (tenuring_threshold > 1) { 1221 tenuring_threshold--; 1222 } 1223 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { 1224 if (tenuring_threshold < MaxTenuringThreshold) { 1225 tenuring_threshold++; 1226 } 1227 } 1228 1229 // We keep a running average of the amount promoted which is used 1230 // to decide when we should collect the old generation (when 1231 // the amount of old gen free space is less than what we expect to 1232 // promote). 1233 1234 if (PrintAdaptiveSizePolicy) { 1235 // A little more detail if Verbose is on 1236 if (Verbose) { 1237 gclog_or_tty->print( " avg_survived: %f" 1238 " avg_deviation: %f", 1239 _avg_survived->average(), 1240 _avg_survived->deviation()); 1241 } 1242 1243 gclog_or_tty->print( " avg_survived_padded_avg: %f", 1244 _avg_survived->padded_average()); 1245 1246 if (Verbose) { 1247 gclog_or_tty->print( " avg_promoted_avg: %f" 1248 " avg_promoted_dev: %f", 1249 avg_promoted()->average(), 1250 avg_promoted()->deviation()); 1251 } 1252 1253 gclog_or_tty->print( " avg_promoted_padded_avg: %f" 1254 " avg_pretenured_padded_avg: %f" 1255 " tenuring_thresh: %d" 1256 " target_size: " SIZE_FORMAT, 1257 avg_promoted()->padded_average(), 1258 _avg_pretenured->padded_average(), 1259 tenuring_threshold, target_size); 1260 tty->cr(); 1261 } 1262 1263 set_survivor_size(target_size); 1264 1265 return tenuring_threshold; 1266 } 1267 1268 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow, 1269 size_t survived, 1270 size_t promoted) { 1271 // Update averages 1272 if (!is_survivor_overflow) { 1273 // Keep running averages on how much survived 1274 _avg_survived->sample(survived); 1275 } else { 1276 size_t survived_guess = survived + promoted; 1277 _avg_survived->sample(survived_guess); 1278 } 1279 avg_promoted()->sample(promoted + _avg_pretenured->padded_average()); 1280 1281 if (PrintAdaptiveSizePolicy) { 1282 gclog_or_tty->print( 1283 "AdaptiveSizePolicy::update_averages:" 1284 " survived: " SIZE_FORMAT 1285 " promoted: " SIZE_FORMAT 1286 " overflow: %s", 1287 survived, promoted, is_survivor_overflow ? "true" : "false"); 1288 } 1289 } 1290 1291 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) 1292 const { 1293 1294 if (!UseAdaptiveSizePolicy) return false; 1295 1296 return AdaptiveSizePolicy::print_adaptive_size_policy_on( 1297 st, 1298 PSScavenge::tenuring_threshold()); 1299 }