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