1 /* 2 * Copyright (c) 2002, 2015, 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/parallel/parallelScavengeHeap.hpp" 27 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 28 #include "gc/parallel/psGCAdaptivePolicyCounters.hpp" 29 #include "gc/parallel/psScavenge.hpp" 30 #include "gc/shared/collectorPolicy.hpp" 31 #include "gc/shared/gcCause.hpp" 32 #include "gc/shared/gcPolicyCounters.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 space_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 / 100.0), 51 _space_alignment(space_alignment), 52 _live_at_last_full_gc(init_promo_size), 53 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec), 54 _latest_major_mutator_interval_seconds(0), 55 _young_gen_change_for_major_pause_count(0) 56 { 57 // Sizing policy statistics 58 _avg_major_pause = 59 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding); 60 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 61 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); 62 63 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); 64 _major_pause_old_estimator = 65 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 66 _major_pause_young_estimator = 67 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 68 _major_collection_estimator = 69 new LinearLeastSquareFit(AdaptiveSizePolicyWeight); 70 71 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement; 72 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement; 73 74 // Start the timers 75 _major_timer.start(); 76 77 _old_gen_policy_is_ready = false; 78 } 79 80 size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) { 81 // We want to calculate how much free memory there can be based on the 82 // amount of live data currently in the old gen. Using the formula: 83 // ratio * (free + live) = free 84 // Some equation solving later we get: 85 // free = (live * ratio) / (1 - ratio) 86 87 const double ratio = ratio_as_percentage / 100.0; 88 const double ratio_inverse = 1.0 - ratio; 89 const double tmp = live * ratio; 90 size_t free = (size_t)(tmp / ratio_inverse); 91 92 return free; 93 } 94 95 size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const { 96 size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average()); 97 size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes(); 98 99 if (MinHeapFreeRatio != 0) { 100 size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio); 101 free_size = MAX2(free_size, min_free); 102 } 103 104 if (MaxHeapFreeRatio != 100) { 105 size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio); 106 free_size = MIN2(max_free, free_size); 107 } 108 109 return free_size; 110 } 111 112 void PSAdaptiveSizePolicy::major_collection_begin() { 113 // Update the interval time 114 _major_timer.stop(); 115 // Save most recent collection time 116 _latest_major_mutator_interval_seconds = _major_timer.seconds(); 117 _major_timer.reset(); 118 _major_timer.start(); 119 } 120 121 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator( 122 double minor_pause_in_ms) { 123 double promo_size_in_mbytes = ((double)_promo_size)/((double)M); 124 _minor_pause_old_estimator->update(promo_size_in_mbytes, 125 minor_pause_in_ms); 126 } 127 128 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live, 129 GCCause::Cause gc_cause) { 130 // Update the pause time. 131 _major_timer.stop(); 132 133 if (gc_cause != GCCause::_java_lang_system_gc || 134 UseAdaptiveSizePolicyWithSystemGC) { 135 double major_pause_in_seconds = _major_timer.seconds(); 136 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS; 137 138 // Sample for performance counter 139 _avg_major_pause->sample(major_pause_in_seconds); 140 141 // Cost of collection (unit-less) 142 double collection_cost = 0.0; 143 if ((_latest_major_mutator_interval_seconds > 0.0) && 144 (major_pause_in_seconds > 0.0)) { 145 double interval_in_seconds = 146 _latest_major_mutator_interval_seconds + major_pause_in_seconds; 147 collection_cost = 148 major_pause_in_seconds / interval_in_seconds; 149 avg_major_gc_cost()->sample(collection_cost); 150 151 // Sample for performance counter 152 _avg_major_interval->sample(interval_in_seconds); 153 } 154 155 // Calculate variables used to estimate pause time vs. gen sizes 156 double eden_size_in_mbytes = ((double)_eden_size)/((double)M); 157 double promo_size_in_mbytes = ((double)_promo_size)/((double)M); 158 _major_pause_old_estimator->update(promo_size_in_mbytes, 159 major_pause_in_ms); 160 _major_pause_young_estimator->update(eden_size_in_mbytes, 161 major_pause_in_ms); 162 163 if (PrintAdaptiveSizePolicy && Verbose) { 164 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: " 165 "major gc cost: %f average: %f", collection_cost, 166 avg_major_gc_cost()->average()); 167 gclog_or_tty->print_cr(" major pause: %f major period %f", 168 major_pause_in_ms, 169 _latest_major_mutator_interval_seconds * MILLIUNITS); 170 } 171 172 // Calculate variable used to estimate collection cost vs. gen sizes 173 assert(collection_cost >= 0.0, "Expected to be non-negative"); 174 _major_collection_estimator->update(promo_size_in_mbytes, 175 collection_cost); 176 } 177 178 // Update the amount live at the end of a full GC 179 _live_at_last_full_gc = amount_live; 180 181 // The policy does not have enough data until at least some major collections 182 // have been done. 183 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) { 184 _old_gen_policy_is_ready = true; 185 } 186 187 // Interval times use this timer to measure the interval that 188 // the mutator runs. Reset after the GC pause has been measured. 189 _major_timer.reset(); 190 _major_timer.start(); 191 } 192 193 // If the remaining free space in the old generation is less that 194 // that expected to be needed by the next collection, do a full 195 // collection now. 196 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) { 197 198 // A similar test is done in the scavenge's should_attempt_scavenge(). If 199 // this is changed, decide if that test should also be changed. 200 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes; 201 if (PrintGCDetails && Verbose) { 202 if (result) { 203 gclog_or_tty->print(" full after scavenge: "); 204 } else { 205 gclog_or_tty->print(" no full after scavenge: "); 206 } 207 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 208 " padded_average_promoted " SIZE_FORMAT 209 " free in old gen " SIZE_FORMAT, 210 (size_t) average_promoted_in_bytes(), 211 (size_t) padded_average_promoted_in_bytes(), 212 old_free_in_bytes); 213 } 214 return result; 215 } 216 217 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() { 218 219 AdaptiveSizePolicy::clear_generation_free_space_flags(); 220 221 set_change_old_gen_for_min_pauses(0); 222 223 set_change_young_gen_for_maj_pauses(0); 224 } 225 226 // If this is not a full GC, only test and modify the young generation. 227 228 void PSAdaptiveSizePolicy::compute_generations_free_space( 229 size_t young_live, 230 size_t eden_live, 231 size_t old_live, 232 size_t cur_eden, 233 size_t max_old_gen_size, 234 size_t max_eden_size, 235 bool is_full_gc) { 236 compute_eden_space_size(young_live, 237 eden_live, 238 cur_eden, 239 max_eden_size, 240 is_full_gc); 241 242 compute_old_gen_free_space(old_live, 243 cur_eden, 244 max_old_gen_size, 245 is_full_gc); 246 } 247 248 void PSAdaptiveSizePolicy::compute_eden_space_size( 249 size_t young_live, 250 size_t eden_live, 251 size_t cur_eden, 252 size_t max_eden_size, 253 bool is_full_gc) { 254 255 // Update statistics 256 // Time statistics are updated as we go, update footprint stats here 257 _avg_base_footprint->sample(BaseFootPrintEstimate); 258 avg_young_live()->sample(young_live); 259 avg_eden_live()->sample(eden_live); 260 261 // This code used to return if the policy was not ready , i.e., 262 // policy_is_ready() returning false. The intent was that 263 // decisions below needed major collection times and so could 264 // not be made before two major collections. A consequence was 265 // adjustments to the young generation were not done until after 266 // two major collections even if the minor collections times 267 // exceeded the requested goals. Now let the young generation 268 // adjust for the minor collection times. Major collection times 269 // will be zero for the first collection and will naturally be 270 // ignored. Tenured generation adjustments are only made at the 271 // full collections so until the second major collection has 272 // been reached, no tenured generation adjustments will be made. 273 274 // Until we know better, desired promotion size uses the last calculation 275 size_t desired_promo_size = _promo_size; 276 277 // Start eden at the current value. The desired value that is stored 278 // in _eden_size is not bounded by constraints of the heap and can 279 // run away. 280 // 281 // As expected setting desired_eden_size to the current 282 // value of desired_eden_size as a starting point 283 // caused desired_eden_size to grow way too large and caused 284 // an overflow down stream. It may have improved performance in 285 // some case but is dangerous. 286 size_t desired_eden_size = cur_eden; 287 288 // Cache some values. There's a bit of work getting these, so 289 // we might save a little time. 290 const double major_cost = major_gc_cost(); 291 const double minor_cost = minor_gc_cost(); 292 293 // This method sets the desired eden size. That plus the 294 // desired survivor space sizes sets the desired young generation 295 // size. This methods does not know what the desired survivor 296 // size is but expects that other policy will attempt to make 297 // the survivor sizes compatible with the live data in the 298 // young generation. This limit is an estimate of the space left 299 // in the young generation after the survivor spaces have been 300 // subtracted out. 301 size_t eden_limit = max_eden_size; 302 303 const double gc_cost_limit = GCTimeLimit/100.0; 304 305 // Which way should we go? 306 // if pause requirement is not met 307 // adjust size of any generation with average paus exceeding 308 // the pause limit. Adjust one pause at a time (the larger) 309 // and only make adjustments for the major pause at full collections. 310 // else if throughput requirement not met 311 // adjust the size of the generation with larger gc time. Only 312 // adjust one generation at a time. 313 // else 314 // adjust down the total heap size. Adjust down the larger of the 315 // generations. 316 317 // Add some checks for a threshold for a change. For example, 318 // a change less than the necessary alignment is probably not worth 319 // attempting. 320 321 322 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || 323 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { 324 // 325 // Check pauses 326 // 327 // Make changes only to affect one of the pauses (the larger) 328 // at a time. 329 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 330 331 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) { 332 // Adjust only for the minor pause time goal 333 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size); 334 335 } else if(adjusted_mutator_cost() < _throughput_goal) { 336 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. 337 // This sometimes resulted in skipping to the minimize footprint 338 // code. Change this to try and reduce GC time if mutator time is 339 // negative for whatever reason. Or for future consideration, 340 // bail out of the code if mutator time is negative. 341 // 342 // Throughput 343 // 344 assert(major_cost >= 0.0, "major cost is < 0.0"); 345 assert(minor_cost >= 0.0, "minor cost is < 0.0"); 346 // Try to reduce the GC times. 347 adjust_eden_for_throughput(is_full_gc, &desired_eden_size); 348 349 } else { 350 351 // Be conservative about reducing the footprint. 352 // Do a minimum number of major collections first. 353 // Have reasonable averages for major and minor collections costs. 354 if (UseAdaptiveSizePolicyFootprintGoal && 355 young_gen_policy_is_ready() && 356 avg_major_gc_cost()->average() >= 0.0 && 357 avg_minor_gc_cost()->average() >= 0.0) { 358 size_t desired_sum = desired_eden_size + desired_promo_size; 359 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum); 360 } 361 } 362 363 // Note we make the same tests as in the code block below; the code 364 // seems a little easier to read with the printing in another block. 365 if (PrintAdaptiveSizePolicy) { 366 if (desired_eden_size > eden_limit) { 367 gclog_or_tty->print_cr( 368 "PSAdaptiveSizePolicy::compute_eden_space_size limits:" 369 " desired_eden_size: " SIZE_FORMAT 370 " old_eden_size: " SIZE_FORMAT 371 " eden_limit: " SIZE_FORMAT 372 " cur_eden: " SIZE_FORMAT 373 " max_eden_size: " SIZE_FORMAT 374 " avg_young_live: " SIZE_FORMAT, 375 desired_eden_size, _eden_size, eden_limit, cur_eden, 376 max_eden_size, (size_t)avg_young_live()->average()); 377 } 378 if (gc_cost() > gc_cost_limit) { 379 gclog_or_tty->print_cr( 380 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit" 381 " gc_cost: %f " 382 " GCTimeLimit: " UINTX_FORMAT, 383 gc_cost(), GCTimeLimit); 384 } 385 } 386 387 // Align everything and make a final limit check 388 desired_eden_size = align_size_up(desired_eden_size, _space_alignment); 389 desired_eden_size = MAX2(desired_eden_size, _space_alignment); 390 391 eden_limit = align_size_down(eden_limit, _space_alignment); 392 393 // And one last limit check, now that we've aligned things. 394 if (desired_eden_size > eden_limit) { 395 // If the policy says to get a larger eden but 396 // is hitting the limit, don't decrease eden. 397 // This can lead to a general drifting down of the 398 // eden size. Let the tenuring calculation push more 399 // into the old gen. 400 desired_eden_size = MAX2(eden_limit, cur_eden); 401 } 402 403 if (PrintAdaptiveSizePolicy) { 404 // Timing stats 405 gclog_or_tty->print( 406 "PSAdaptiveSizePolicy::compute_eden_space_size: costs" 407 " minor_time: %f" 408 " major_cost: %f" 409 " mutator_cost: %f" 410 " throughput_goal: %f", 411 minor_gc_cost(), major_gc_cost(), mutator_cost(), 412 _throughput_goal); 413 414 // We give more details if Verbose is set 415 if (Verbose) { 416 gclog_or_tty->print( " minor_pause: %f" 417 " major_pause: %f" 418 " minor_interval: %f" 419 " major_interval: %f" 420 " pause_goal: %f", 421 _avg_minor_pause->padded_average(), 422 _avg_major_pause->padded_average(), 423 _avg_minor_interval->average(), 424 _avg_major_interval->average(), 425 gc_pause_goal_sec()); 426 } 427 428 // Footprint stats 429 gclog_or_tty->print( " live_space: " SIZE_FORMAT 430 " free_space: " SIZE_FORMAT, 431 live_space(), free_space()); 432 // More detail 433 if (Verbose) { 434 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT 435 " avg_young_live: " SIZE_FORMAT 436 " avg_old_live: " SIZE_FORMAT, 437 (size_t)_avg_base_footprint->average(), 438 (size_t)avg_young_live()->average(), 439 (size_t)avg_old_live()->average()); 440 } 441 442 // And finally, our old and new sizes. 443 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT 444 " desired_eden_size: " SIZE_FORMAT, 445 _eden_size, desired_eden_size); 446 gclog_or_tty->cr(); 447 } 448 449 set_eden_size(desired_eden_size); 450 } 451 452 void PSAdaptiveSizePolicy::compute_old_gen_free_space( 453 size_t old_live, 454 size_t cur_eden, 455 size_t max_old_gen_size, 456 bool is_full_gc) { 457 458 // Update statistics 459 // Time statistics are updated as we go, update footprint stats here 460 if (is_full_gc) { 461 // old_live is only accurate after a full gc 462 avg_old_live()->sample(old_live); 463 } 464 465 // This code used to return if the policy was not ready , i.e., 466 // policy_is_ready() returning false. The intent was that 467 // decisions below needed major collection times and so could 468 // not be made before two major collections. A consequence was 469 // adjustments to the young generation were not done until after 470 // two major collections even if the minor collections times 471 // exceeded the requested goals. Now let the young generation 472 // adjust for the minor collection times. Major collection times 473 // will be zero for the first collection and will naturally be 474 // ignored. Tenured generation adjustments are only made at the 475 // full collections so until the second major collection has 476 // been reached, no tenured generation adjustments will be made. 477 478 // Until we know better, desired promotion size uses the last calculation 479 size_t desired_promo_size = _promo_size; 480 481 // Start eden at the current value. The desired value that is stored 482 // in _eden_size is not bounded by constraints of the heap and can 483 // run away. 484 // 485 // As expected setting desired_eden_size to the current 486 // value of desired_eden_size as a starting point 487 // caused desired_eden_size to grow way too large and caused 488 // an overflow down stream. It may have improved performance in 489 // some case but is dangerous. 490 size_t desired_eden_size = cur_eden; 491 492 // Cache some values. There's a bit of work getting these, so 493 // we might save a little time. 494 const double major_cost = major_gc_cost(); 495 const double minor_cost = minor_gc_cost(); 496 497 // Limits on our growth 498 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average()); 499 500 // But don't force a promo size below the current promo size. Otherwise, 501 // the promo size will shrink for no good reason. 502 promo_limit = MAX2(promo_limit, _promo_size); 503 504 const double gc_cost_limit = GCTimeLimit/100.0; 505 506 // Which way should we go? 507 // if pause requirement is not met 508 // adjust size of any generation with average paus exceeding 509 // the pause limit. Adjust one pause at a time (the larger) 510 // and only make adjustments for the major pause at full collections. 511 // else if throughput requirement not met 512 // adjust the size of the generation with larger gc time. Only 513 // adjust one generation at a time. 514 // else 515 // adjust down the total heap size. Adjust down the larger of the 516 // generations. 517 518 // Add some checks for a threshold for a change. For example, 519 // a change less than the necessary alignment is probably not worth 520 // attempting. 521 522 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || 523 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { 524 // 525 // Check pauses 526 // 527 // Make changes only to affect one of the pauses (the larger) 528 // at a time. 529 if (is_full_gc) { 530 set_decide_at_full_gc(decide_at_full_gc_true); 531 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 532 } 533 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) { 534 // Adjust only for the minor pause time goal 535 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); 536 } else if(adjusted_mutator_cost() < _throughput_goal) { 537 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. 538 // This sometimes resulted in skipping to the minimize footprint 539 // code. Change this to try and reduce GC time if mutator time is 540 // negative for whatever reason. Or for future consideration, 541 // bail out of the code if mutator time is negative. 542 // 543 // Throughput 544 // 545 assert(major_cost >= 0.0, "major cost is < 0.0"); 546 assert(minor_cost >= 0.0, "minor cost is < 0.0"); 547 // Try to reduce the GC times. 548 if (is_full_gc) { 549 set_decide_at_full_gc(decide_at_full_gc_true); 550 adjust_promo_for_throughput(is_full_gc, &desired_promo_size); 551 } 552 } else { 553 554 // Be conservative about reducing the footprint. 555 // Do a minimum number of major collections first. 556 // Have reasonable averages for major and minor collections costs. 557 if (UseAdaptiveSizePolicyFootprintGoal && 558 young_gen_policy_is_ready() && 559 avg_major_gc_cost()->average() >= 0.0 && 560 avg_minor_gc_cost()->average() >= 0.0) { 561 if (is_full_gc) { 562 set_decide_at_full_gc(decide_at_full_gc_true); 563 size_t desired_sum = desired_eden_size + desired_promo_size; 564 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum); 565 } 566 } 567 } 568 569 // Note we make the same tests as in the code block below; the code 570 // seems a little easier to read with the printing in another block. 571 if (PrintAdaptiveSizePolicy) { 572 if (desired_promo_size > promo_limit) { 573 // "free_in_old_gen" was the original value for used for promo_limit 574 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average()); 575 gclog_or_tty->print_cr( 576 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:" 577 " desired_promo_size: " SIZE_FORMAT 578 " promo_limit: " SIZE_FORMAT 579 " free_in_old_gen: " SIZE_FORMAT 580 " max_old_gen_size: " SIZE_FORMAT 581 " avg_old_live: " SIZE_FORMAT, 582 desired_promo_size, promo_limit, free_in_old_gen, 583 max_old_gen_size, (size_t) avg_old_live()->average()); 584 } 585 if (gc_cost() > gc_cost_limit) { 586 gclog_or_tty->print_cr( 587 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit" 588 " gc_cost: %f " 589 " GCTimeLimit: " UINTX_FORMAT, 590 gc_cost(), GCTimeLimit); 591 } 592 } 593 594 // Align everything and make a final limit check 595 desired_promo_size = align_size_up(desired_promo_size, _space_alignment); 596 desired_promo_size = MAX2(desired_promo_size, _space_alignment); 597 598 promo_limit = align_size_down(promo_limit, _space_alignment); 599 600 // And one last limit check, now that we've aligned things. 601 desired_promo_size = MIN2(desired_promo_size, promo_limit); 602 603 if (PrintAdaptiveSizePolicy) { 604 // Timing stats 605 gclog_or_tty->print( 606 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs" 607 " minor_time: %f" 608 " major_cost: %f" 609 " mutator_cost: %f" 610 " throughput_goal: %f", 611 minor_gc_cost(), major_gc_cost(), mutator_cost(), 612 _throughput_goal); 613 614 // We give more details if Verbose is set 615 if (Verbose) { 616 gclog_or_tty->print( " minor_pause: %f" 617 " major_pause: %f" 618 " minor_interval: %f" 619 " major_interval: %f" 620 " pause_goal: %f", 621 _avg_minor_pause->padded_average(), 622 _avg_major_pause->padded_average(), 623 _avg_minor_interval->average(), 624 _avg_major_interval->average(), 625 gc_pause_goal_sec()); 626 } 627 628 // Footprint stats 629 gclog_or_tty->print( " live_space: " SIZE_FORMAT 630 " free_space: " SIZE_FORMAT, 631 live_space(), free_space()); 632 // More detail 633 if (Verbose) { 634 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT 635 " avg_young_live: " SIZE_FORMAT 636 " avg_old_live: " SIZE_FORMAT, 637 (size_t)_avg_base_footprint->average(), 638 (size_t)avg_young_live()->average(), 639 (size_t)avg_old_live()->average()); 640 } 641 642 // And finally, our old and new sizes. 643 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT 644 " desired_promo_size: " SIZE_FORMAT, 645 _promo_size, desired_promo_size); 646 gclog_or_tty->cr(); 647 } 648 649 set_promo_size(desired_promo_size); 650 } 651 652 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) { 653 // Decay the supplemental increment? Decay the supplement growth 654 // factor even if it is not used. It is only meant to give a boost 655 // to the initial growth and if it is not used, then it was not 656 // needed. 657 if (is_full_gc) { 658 // Don't wait for the threshold value for the major collections. If 659 // here, the supplemental growth term was used and should decay. 660 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay) 661 == 0) { 662 _old_gen_size_increment_supplement = 663 _old_gen_size_increment_supplement >> 1; 664 } 665 } else { 666 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) && 667 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) { 668 _young_gen_size_increment_supplement = 669 _young_gen_size_increment_supplement >> 1; 670 } 671 } 672 } 673 674 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc, 675 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) { 676 677 if (PSAdjustTenuredGenForMinorPause) { 678 if (is_full_gc) { 679 set_decide_at_full_gc(decide_at_full_gc_true); 680 } 681 // If the desired eden size is as small as it will get, 682 // try to adjust the old gen size. 683 if (*desired_eden_size_ptr <= _space_alignment) { 684 // Vary the old gen size to reduce the young gen pause. This 685 // may not be a good idea. This is just a test. 686 if (minor_pause_old_estimator()->decrement_will_decrease()) { 687 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true); 688 *desired_promo_size_ptr = 689 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr); 690 } else { 691 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true); 692 size_t promo_heap_delta = 693 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 694 if ((*desired_promo_size_ptr + promo_heap_delta) > 695 *desired_promo_size_ptr) { 696 *desired_promo_size_ptr = 697 _promo_size + promo_heap_delta; 698 } 699 } 700 } 701 } 702 } 703 704 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc, 705 size_t* desired_eden_size_ptr) { 706 707 // Adjust the young generation size to reduce pause time of 708 // of collections. 709 // 710 // The AdaptiveSizePolicyInitializingSteps test is not used 711 // here. It has not seemed to be needed but perhaps should 712 // be added for consistency. 713 if (minor_pause_young_estimator()->decrement_will_decrease()) { 714 // reduce eden size 715 set_change_young_gen_for_min_pauses( 716 decrease_young_gen_for_min_pauses_true); 717 *desired_eden_size_ptr = *desired_eden_size_ptr - 718 eden_decrement_aligned_down(*desired_eden_size_ptr); 719 } else { 720 // EXPERIMENTAL ADJUSTMENT 721 // Only record that the estimator indicated such an action. 722 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta; 723 set_change_young_gen_for_min_pauses( 724 increase_young_gen_for_min_pauses_true); 725 } 726 } 727 728 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc, 729 size_t* desired_promo_size_ptr, 730 size_t* desired_eden_size_ptr) { 731 732 size_t promo_heap_delta = 0; 733 // Add some checks for a threshold for a change. For example, 734 // a change less than the required alignment is probably not worth 735 // attempting. 736 737 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) { 738 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr); 739 // major pause adjustments 740 } else if (is_full_gc) { 741 // Adjust for the major pause time only at full gc's because the 742 // affects of a change can only be seen at full gc's. 743 744 // Reduce old generation size to reduce pause? 745 if (major_pause_old_estimator()->decrement_will_decrease()) { 746 // reduce old generation size 747 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true); 748 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr); 749 *desired_promo_size_ptr = _promo_size - promo_heap_delta; 750 } else { 751 // EXPERIMENTAL ADJUSTMENT 752 // Only record that the estimator indicated such an action. 753 // *desired_promo_size_ptr = _promo_size + 754 // promo_increment_aligned_up(*desired_promo_size_ptr); 755 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true); 756 } 757 } 758 759 if (PrintAdaptiveSizePolicy && Verbose) { 760 gclog_or_tty->print_cr( 761 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time " 762 "adjusting gen sizes for major pause (avg %f goal %f). " 763 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT, 764 _avg_major_pause->average(), gc_pause_goal_sec(), 765 *desired_promo_size_ptr, promo_heap_delta); 766 } 767 } 768 769 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc, 770 size_t* desired_promo_size_ptr, 771 size_t* desired_eden_size_ptr) { 772 773 size_t eden_heap_delta = 0; 774 // Add some checks for a threshold for a change. For example, 775 // a change less than the required alignment is probably not worth 776 // attempting. 777 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) { 778 adjust_eden_for_minor_pause_time(is_full_gc, 779 desired_eden_size_ptr); 780 // major pause adjustments 781 } else if (is_full_gc) { 782 // Adjust for the major pause time only at full gc's because the 783 // affects of a change can only be seen at full gc's. 784 if (PSAdjustYoungGenForMajorPause) { 785 // If the promo size is at the minimum (i.e., the old gen 786 // size will not actually decrease), consider changing the 787 // young gen size. 788 if (*desired_promo_size_ptr < _space_alignment) { 789 // If increasing the young generation will decrease the old gen 790 // pause, do it. 791 // During startup there is noise in the statistics for deciding 792 // on whether to increase or decrease the young gen size. For 793 // some number of iterations, just try to increase the young 794 // gen size if the major pause is too long to try and establish 795 // good statistics for later decisions. 796 if (major_pause_young_estimator()->increment_will_decrease() || 797 (_young_gen_change_for_major_pause_count 798 <= AdaptiveSizePolicyInitializingSteps)) { 799 set_change_young_gen_for_maj_pauses( 800 increase_young_gen_for_maj_pauses_true); 801 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr); 802 *desired_eden_size_ptr = _eden_size + eden_heap_delta; 803 _young_gen_change_for_major_pause_count++; 804 } else { 805 // Record that decreasing the young gen size would decrease 806 // the major pause 807 set_change_young_gen_for_maj_pauses( 808 decrease_young_gen_for_maj_pauses_true); 809 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr); 810 *desired_eden_size_ptr = _eden_size - eden_heap_delta; 811 } 812 } 813 } 814 } 815 816 if (PrintAdaptiveSizePolicy && Verbose) { 817 gclog_or_tty->print_cr( 818 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time " 819 "adjusting gen sizes for major pause (avg %f goal %f). " 820 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT, 821 _avg_major_pause->average(), gc_pause_goal_sec(), 822 *desired_eden_size_ptr, eden_heap_delta); 823 } 824 } 825 826 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc, 827 size_t* desired_promo_size_ptr) { 828 829 // Add some checks for a threshold for a change. For example, 830 // a change less than the required alignment is probably not worth 831 // attempting. 832 833 if ((gc_cost() + mutator_cost()) == 0.0) { 834 return; 835 } 836 837 if (PrintAdaptiveSizePolicy && Verbose) { 838 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput(" 839 "is_full: %d, promo: " SIZE_FORMAT "): ", 840 is_full_gc, *desired_promo_size_ptr); 841 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f " 842 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost()); 843 } 844 845 // Tenured generation 846 if (is_full_gc) { 847 // Calculate the change to use for the tenured gen. 848 size_t scaled_promo_heap_delta = 0; 849 // Can the increment to the generation be scaled? 850 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) { 851 size_t promo_heap_delta = 852 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 853 double scale_by_ratio = major_gc_cost() / gc_cost(); 854 scaled_promo_heap_delta = 855 (size_t) (scale_by_ratio * (double) promo_heap_delta); 856 if (PrintAdaptiveSizePolicy && Verbose) { 857 gclog_or_tty->print_cr( 858 "Scaled tenured increment: " SIZE_FORMAT " by %f down to " 859 SIZE_FORMAT, 860 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta); 861 } 862 } else if (major_gc_cost() >= 0.0) { 863 // Scaling is not going to work. If the major gc time is the 864 // larger, give it a full increment. 865 if (major_gc_cost() >= minor_gc_cost()) { 866 scaled_promo_heap_delta = 867 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); 868 } 869 } else { 870 // Don't expect to get here but it's ok if it does 871 // in the product build since the delta will be 0 872 // and nothing will change. 873 assert(false, "Unexpected value for gc costs"); 874 } 875 876 switch (AdaptiveSizeThroughPutPolicy) { 877 case 1: 878 // Early in the run the statistics might not be good. Until 879 // a specific number of collections have been, use the heuristic 880 // that a larger generation size means lower collection costs. 881 if (major_collection_estimator()->increment_will_decrease() || 882 (_old_gen_change_for_major_throughput 883 <= AdaptiveSizePolicyInitializingSteps)) { 884 // Increase tenured generation size to reduce major collection cost 885 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > 886 *desired_promo_size_ptr) { 887 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta; 888 } 889 set_change_old_gen_for_throughput( 890 increase_old_gen_for_throughput_true); 891 _old_gen_change_for_major_throughput++; 892 } else { 893 // EXPERIMENTAL ADJUSTMENT 894 // Record that decreasing the old gen size would decrease 895 // the major collection cost but don't do it. 896 // *desired_promo_size_ptr = _promo_size - 897 // promo_decrement_aligned_down(*desired_promo_size_ptr); 898 set_change_old_gen_for_throughput( 899 decrease_old_gen_for_throughput_true); 900 } 901 902 break; 903 default: 904 // Simplest strategy 905 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > 906 *desired_promo_size_ptr) { 907 *desired_promo_size_ptr = *desired_promo_size_ptr + 908 scaled_promo_heap_delta; 909 } 910 set_change_old_gen_for_throughput( 911 increase_old_gen_for_throughput_true); 912 _old_gen_change_for_major_throughput++; 913 } 914 915 if (PrintAdaptiveSizePolicy && Verbose) { 916 gclog_or_tty->print_cr( 917 "adjusting tenured gen for throughput (avg %f goal %f). " 918 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT , 919 mutator_cost(), _throughput_goal, 920 *desired_promo_size_ptr, scaled_promo_heap_delta); 921 } 922 } 923 } 924 925 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc, 926 size_t* desired_eden_size_ptr) { 927 928 // Add some checks for a threshold for a change. For example, 929 // a change less than the required alignment is probably not worth 930 // attempting. 931 932 if ((gc_cost() + mutator_cost()) == 0.0) { 933 return; 934 } 935 936 if (PrintAdaptiveSizePolicy && Verbose) { 937 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput(" 938 "is_full: %d, cur_eden: " SIZE_FORMAT "): ", 939 is_full_gc, *desired_eden_size_ptr); 940 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f " 941 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost()); 942 } 943 944 // Young generation 945 size_t scaled_eden_heap_delta = 0; 946 // Can the increment to the generation be scaled? 947 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) { 948 size_t eden_heap_delta = 949 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); 950 double scale_by_ratio = minor_gc_cost() / gc_cost(); 951 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong"); 952 scaled_eden_heap_delta = 953 (size_t) (scale_by_ratio * (double) eden_heap_delta); 954 if (PrintAdaptiveSizePolicy && Verbose) { 955 gclog_or_tty->print_cr( 956 "Scaled eden increment: " SIZE_FORMAT " by %f down to " 957 SIZE_FORMAT, 958 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta); 959 } 960 } else if (minor_gc_cost() >= 0.0) { 961 // Scaling is not going to work. If the minor gc time is the 962 // larger, give it a full increment. 963 if (minor_gc_cost() > major_gc_cost()) { 964 scaled_eden_heap_delta = 965 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); 966 } 967 } else { 968 // Don't expect to get here but it's ok if it does 969 // in the product build since the delta will be 0 970 // and nothing will change. 971 assert(false, "Unexpected value for gc costs"); 972 } 973 974 // Use a heuristic for some number of collections to give 975 // the averages time to settle down. 976 switch (AdaptiveSizeThroughPutPolicy) { 977 case 1: 978 if (minor_collection_estimator()->increment_will_decrease() || 979 (_young_gen_change_for_minor_throughput 980 <= AdaptiveSizePolicyInitializingSteps)) { 981 // Expand young generation size to reduce frequency of 982 // of collections. 983 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > 984 *desired_eden_size_ptr) { 985 *desired_eden_size_ptr = 986 *desired_eden_size_ptr + scaled_eden_heap_delta; 987 } 988 set_change_young_gen_for_throughput( 989 increase_young_gen_for_througput_true); 990 _young_gen_change_for_minor_throughput++; 991 } else { 992 // EXPERIMENTAL ADJUSTMENT 993 // Record that decreasing the young gen size would decrease 994 // the minor collection cost but don't do it. 995 // *desired_eden_size_ptr = _eden_size - 996 // eden_decrement_aligned_down(*desired_eden_size_ptr); 997 set_change_young_gen_for_throughput( 998 decrease_young_gen_for_througput_true); 999 } 1000 break; 1001 default: 1002 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > 1003 *desired_eden_size_ptr) { 1004 *desired_eden_size_ptr = 1005 *desired_eden_size_ptr + scaled_eden_heap_delta; 1006 } 1007 set_change_young_gen_for_throughput( 1008 increase_young_gen_for_througput_true); 1009 _young_gen_change_for_minor_throughput++; 1010 } 1011 1012 if (PrintAdaptiveSizePolicy && Verbose) { 1013 gclog_or_tty->print_cr( 1014 "adjusting eden for throughput (avg %f goal %f). desired_eden_size " 1015 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n", 1016 mutator_cost(), _throughput_goal, 1017 *desired_eden_size_ptr, scaled_eden_heap_delta); 1018 } 1019 } 1020 1021 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint( 1022 size_t desired_promo_size, size_t desired_sum) { 1023 assert(desired_promo_size <= desired_sum, "Inconsistent parameters"); 1024 set_decrease_for_footprint(decrease_old_gen_for_footprint_true); 1025 1026 size_t change = promo_decrement(desired_promo_size); 1027 change = scale_down(change, desired_promo_size, desired_sum); 1028 1029 size_t reduced_size = desired_promo_size - change; 1030 1031 if (PrintAdaptiveSizePolicy && Verbose) { 1032 gclog_or_tty->print_cr( 1033 "AdaptiveSizePolicy::adjust_promo_for_footprint " 1034 "adjusting tenured gen for footprint. " 1035 "starting promo size " SIZE_FORMAT 1036 " reduced promo size " SIZE_FORMAT 1037 " promo delta " SIZE_FORMAT, 1038 desired_promo_size, reduced_size, change ); 1039 } 1040 1041 assert(reduced_size <= desired_promo_size, "Inconsistent result"); 1042 return reduced_size; 1043 } 1044 1045 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint( 1046 size_t desired_eden_size, size_t desired_sum) { 1047 assert(desired_eden_size <= desired_sum, "Inconsistent parameters"); 1048 set_decrease_for_footprint(decrease_young_gen_for_footprint_true); 1049 1050 size_t change = eden_decrement(desired_eden_size); 1051 change = scale_down(change, desired_eden_size, desired_sum); 1052 1053 size_t reduced_size = desired_eden_size - change; 1054 1055 if (PrintAdaptiveSizePolicy && Verbose) { 1056 gclog_or_tty->print_cr( 1057 "AdaptiveSizePolicy::adjust_eden_for_footprint " 1058 "adjusting eden for footprint. " 1059 " starting eden size " SIZE_FORMAT 1060 " reduced eden size " SIZE_FORMAT 1061 " eden delta " SIZE_FORMAT, 1062 desired_eden_size, reduced_size, change); 1063 } 1064 1065 assert(reduced_size <= desired_eden_size, "Inconsistent result"); 1066 return reduced_size; 1067 } 1068 1069 // Scale down "change" by the factor 1070 // part / total 1071 // Don't align the results. 1072 1073 size_t PSAdaptiveSizePolicy::scale_down(size_t change, 1074 double part, 1075 double total) { 1076 assert(part <= total, "Inconsistent input"); 1077 size_t reduced_change = change; 1078 if (total > 0) { 1079 double fraction = part / total; 1080 reduced_change = (size_t) (fraction * (double) change); 1081 } 1082 assert(reduced_change <= change, "Inconsistent result"); 1083 return reduced_change; 1084 } 1085 1086 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden, 1087 uint percent_change) { 1088 size_t eden_heap_delta; 1089 eden_heap_delta = cur_eden / 100 * percent_change; 1090 return eden_heap_delta; 1091 } 1092 1093 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) { 1094 return eden_increment(cur_eden, YoungGenerationSizeIncrement); 1095 } 1096 1097 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) { 1098 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement); 1099 return align_size_up(result, _space_alignment); 1100 } 1101 1102 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) { 1103 size_t result = eden_increment(cur_eden); 1104 return align_size_down(result, _space_alignment); 1105 } 1106 1107 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up( 1108 size_t cur_eden) { 1109 size_t result = eden_increment(cur_eden, 1110 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement); 1111 return align_size_up(result, _space_alignment); 1112 } 1113 1114 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) { 1115 size_t eden_heap_delta = eden_decrement(cur_eden); 1116 return align_size_down(eden_heap_delta, _space_alignment); 1117 } 1118 1119 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) { 1120 size_t eden_heap_delta = eden_increment(cur_eden) / 1121 AdaptiveSizeDecrementScaleFactor; 1122 return eden_heap_delta; 1123 } 1124 1125 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo, 1126 uint percent_change) { 1127 size_t promo_heap_delta; 1128 promo_heap_delta = cur_promo / 100 * percent_change; 1129 return promo_heap_delta; 1130 } 1131 1132 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) { 1133 return promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1134 } 1135 1136 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) { 1137 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1138 return align_size_up(result, _space_alignment); 1139 } 1140 1141 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) { 1142 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); 1143 return align_size_down(result, _space_alignment); 1144 } 1145 1146 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up( 1147 size_t cur_promo) { 1148 size_t result = promo_increment(cur_promo, 1149 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement); 1150 return align_size_up(result, _space_alignment); 1151 } 1152 1153 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) { 1154 size_t promo_heap_delta = promo_decrement(cur_promo); 1155 return align_size_down(promo_heap_delta, _space_alignment); 1156 } 1157 1158 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) { 1159 size_t promo_heap_delta = promo_increment(cur_promo); 1160 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor; 1161 return promo_heap_delta; 1162 } 1163 1164 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold( 1165 bool is_survivor_overflow, 1166 uint tenuring_threshold, 1167 size_t survivor_limit) { 1168 assert(survivor_limit >= _space_alignment, 1169 "survivor_limit too small"); 1170 assert((size_t)align_size_down(survivor_limit, _space_alignment) 1171 == survivor_limit, "survivor_limit not aligned"); 1172 1173 // This method is called even if the tenuring threshold and survivor 1174 // spaces are not adjusted so that the averages are sampled above. 1175 if (!UsePSAdaptiveSurvivorSizePolicy || 1176 !young_gen_policy_is_ready()) { 1177 return tenuring_threshold; 1178 } 1179 1180 // We'll decide whether to increase or decrease the tenuring 1181 // threshold based partly on the newly computed survivor size 1182 // (if we hit the maximum limit allowed, we'll always choose to 1183 // decrement the threshold). 1184 bool incr_tenuring_threshold = false; 1185 bool decr_tenuring_threshold = false; 1186 1187 set_decrement_tenuring_threshold_for_gc_cost(false); 1188 set_increment_tenuring_threshold_for_gc_cost(false); 1189 set_decrement_tenuring_threshold_for_survivor_limit(false); 1190 1191 if (!is_survivor_overflow) { 1192 // Keep running averages on how much survived 1193 1194 // We use the tenuring threshold to equalize the cost of major 1195 // and minor collections. 1196 // ThresholdTolerance is used to indicate how sensitive the 1197 // tenuring threshold is to differences in cost between the 1198 // collection types. 1199 1200 // Get the times of interest. This involves a little work, so 1201 // we cache the values here. 1202 const double major_cost = major_gc_cost(); 1203 const double minor_cost = minor_gc_cost(); 1204 1205 if (minor_cost > major_cost * _threshold_tolerance_percent) { 1206 // Minor times are getting too long; lower the threshold so 1207 // less survives and more is promoted. 1208 decr_tenuring_threshold = true; 1209 set_decrement_tenuring_threshold_for_gc_cost(true); 1210 } else if (major_cost > minor_cost * _threshold_tolerance_percent) { 1211 // Major times are too long, so we want less promotion. 1212 incr_tenuring_threshold = true; 1213 set_increment_tenuring_threshold_for_gc_cost(true); 1214 } 1215 1216 } else { 1217 // Survivor space overflow occurred, so promoted and survived are 1218 // not accurate. We'll make our best guess by combining survived 1219 // and promoted and count them as survivors. 1220 // 1221 // We'll lower the tenuring threshold to see if we can correct 1222 // things. Also, set the survivor size conservatively. We're 1223 // trying to avoid many overflows from occurring if defnew size 1224 // is just too small. 1225 1226 decr_tenuring_threshold = true; 1227 } 1228 1229 // The padded average also maintains a deviation from the average; 1230 // we use this to see how good of an estimate we have of what survived. 1231 // We're trying to pad the survivor size as little as possible without 1232 // overflowing the survivor spaces. 1233 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(), 1234 _space_alignment); 1235 target_size = MAX2(target_size, _space_alignment); 1236 1237 if (target_size > survivor_limit) { 1238 // Target size is bigger than we can handle. Let's also reduce 1239 // the tenuring threshold. 1240 target_size = survivor_limit; 1241 decr_tenuring_threshold = true; 1242 set_decrement_tenuring_threshold_for_survivor_limit(true); 1243 } 1244 1245 // Finally, increment or decrement the tenuring threshold, as decided above. 1246 // We test for decrementing first, as we might have hit the target size 1247 // limit. 1248 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { 1249 if (tenuring_threshold > 1) { 1250 tenuring_threshold--; 1251 } 1252 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { 1253 if (tenuring_threshold < MaxTenuringThreshold) { 1254 tenuring_threshold++; 1255 } 1256 } 1257 1258 // We keep a running average of the amount promoted which is used 1259 // to decide when we should collect the old generation (when 1260 // the amount of old gen free space is less than what we expect to 1261 // promote). 1262 1263 if (PrintAdaptiveSizePolicy) { 1264 // A little more detail if Verbose is on 1265 if (Verbose) { 1266 gclog_or_tty->print( " avg_survived: %f" 1267 " avg_deviation: %f", 1268 _avg_survived->average(), 1269 _avg_survived->deviation()); 1270 } 1271 1272 gclog_or_tty->print( " avg_survived_padded_avg: %f", 1273 _avg_survived->padded_average()); 1274 1275 if (Verbose) { 1276 gclog_or_tty->print( " avg_promoted_avg: %f" 1277 " avg_promoted_dev: %f", 1278 avg_promoted()->average(), 1279 avg_promoted()->deviation()); 1280 } 1281 1282 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f" 1283 " avg_pretenured_padded_avg: %f" 1284 " tenuring_thresh: %d" 1285 " target_size: " SIZE_FORMAT, 1286 avg_promoted()->padded_average(), 1287 _avg_pretenured->padded_average(), 1288 tenuring_threshold, target_size); 1289 } 1290 1291 set_survivor_size(target_size); 1292 1293 return tenuring_threshold; 1294 } 1295 1296 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow, 1297 size_t survived, 1298 size_t promoted) { 1299 // Update averages 1300 if (!is_survivor_overflow) { 1301 // Keep running averages on how much survived 1302 _avg_survived->sample(survived); 1303 } else { 1304 size_t survived_guess = survived + promoted; 1305 _avg_survived->sample(survived_guess); 1306 } 1307 avg_promoted()->sample(promoted + _avg_pretenured->padded_average()); 1308 1309 if (PrintAdaptiveSizePolicy) { 1310 gclog_or_tty->print_cr( 1311 "AdaptiveSizePolicy::update_averages:" 1312 " survived: " SIZE_FORMAT 1313 " promoted: " SIZE_FORMAT 1314 " overflow: %s", 1315 survived, promoted, is_survivor_overflow ? "true" : "false"); 1316 } 1317 } 1318 1319 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) 1320 const { 1321 1322 if (!UseAdaptiveSizePolicy) return false; 1323 1324 return AdaptiveSizePolicy::print_adaptive_size_policy_on( 1325 st, 1326 PSScavenge::tenuring_threshold()); 1327 } 1328 1329 #ifndef PRODUCT 1330 1331 void TestOldFreeSpaceCalculation_test() { 1332 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed"); 1333 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed"); 1334 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed"); 1335 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed"); 1336 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed"); 1337 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed"); 1338 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed"); 1339 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed"); 1340 } 1341 1342 #endif /* !PRODUCT */