1 /* 2 * Copyright (c) 2016, 2019, 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/g1/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/g1CollectionSet.hpp" 28 #include "gc/g1/g1CollectionSetCandidates.hpp" 29 #include "gc/g1/g1CollectorState.hpp" 30 #include "gc/g1/g1HotCardCache.hpp" 31 #include "gc/g1/g1ParScanThreadState.hpp" 32 #include "gc/g1/g1Policy.hpp" 33 #include "gc/g1/heapRegion.inline.hpp" 34 #include "gc/g1/heapRegionRemSet.hpp" 35 #include "gc/g1/heapRegionSet.hpp" 36 #include "logging/logStream.hpp" 37 #include "utilities/debug.hpp" 38 #include "utilities/globalDefinitions.hpp" 39 #include "utilities/quickSort.hpp" 40 41 G1CollectorState* G1CollectionSet::collector_state() const { 42 return _g1h->collector_state(); 43 } 44 45 G1GCPhaseTimes* G1CollectionSet::phase_times() { 46 return _policy->phase_times(); 47 } 48 49 double G1CollectionSet::predict_region_non_copy_time_ms(HeapRegion* hr) const { 50 return _policy->predict_region_non_copy_time_ms(hr, collector_state()->in_young_only_phase()); 51 } 52 53 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) : 54 _g1h(g1h), 55 _policy(policy), 56 _candidates(NULL), 57 _eden_region_length(0), 58 _survivor_region_length(0), 59 _old_region_length(0), 60 _collection_set_regions(NULL), 61 _collection_set_cur_length(0), 62 _collection_set_max_length(0), 63 _num_optional_regions(0), 64 _bytes_used_before(0), 65 _recorded_rs_length(0), 66 _inc_build_state(Inactive), 67 _inc_part_start(0), 68 _inc_collection_set_stats(NULL), 69 _inc_bytes_used_before(0), 70 _inc_recorded_rs_length(0), 71 _inc_recorded_rs_length_diff(0), 72 _inc_predicted_non_copy_time_ms(0.0), 73 _inc_predicted_non_copy_time_ms_diff(0.0) { 74 } 75 76 G1CollectionSet::~G1CollectionSet() { 77 FREE_C_HEAP_ARRAY(uint, _collection_set_regions); 78 FREE_C_HEAP_ARRAY(IncCollectionSetRegionStat, _inc_collection_set_stats); 79 free_optional_regions(); 80 clear_candidates(); 81 } 82 83 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length, 84 uint survivor_cset_region_length) { 85 assert_at_safepoint_on_vm_thread(); 86 87 _eden_region_length = eden_cset_region_length; 88 _survivor_region_length = survivor_cset_region_length; 89 90 assert((size_t) young_region_length() == _collection_set_cur_length, 91 "Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length); 92 93 _old_region_length = 0; 94 free_optional_regions(); 95 } 96 97 void G1CollectionSet::initialize(uint max_region_length) { 98 guarantee(_collection_set_regions == NULL, "Must only initialize once."); 99 _collection_set_max_length = max_region_length; 100 _collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC); 101 _inc_collection_set_stats = NEW_C_HEAP_ARRAY(IncCollectionSetRegionStat, max_region_length, mtGC); 102 } 103 104 void G1CollectionSet::free_optional_regions() { 105 _num_optional_regions = 0; 106 } 107 108 void G1CollectionSet::clear_candidates() { 109 delete _candidates; 110 _candidates = NULL; 111 } 112 113 void G1CollectionSet::set_recorded_rs_length(size_t rs_length) { 114 _recorded_rs_length = rs_length; 115 } 116 117 // Add the heap region at the head of the non-incremental collection set 118 void G1CollectionSet::add_old_region(HeapRegion* hr) { 119 assert_at_safepoint_on_vm_thread(); 120 121 assert(_inc_build_state == Active, 122 "Precondition, actively building cset or adding optional later on"); 123 assert(hr->is_old(), "the region should be old"); 124 125 assert(!hr->in_collection_set(), "should not already be in the collection set"); 126 _g1h->register_old_region_with_region_attr(hr); 127 128 _collection_set_regions[_collection_set_cur_length++] = hr->hrm_index(); 129 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size."); 130 131 _bytes_used_before += hr->used(); 132 _recorded_rs_length += hr->rem_set()->occupied(); 133 _old_region_length++; 134 135 _g1h->old_set_remove(hr); 136 } 137 138 void G1CollectionSet::add_optional_region(HeapRegion* hr) { 139 assert(hr->is_old(), "the region should be old"); 140 assert(!hr->in_collection_set(), "should not already be in the CSet"); 141 142 _g1h->register_optional_region_with_region_attr(hr); 143 144 hr->set_index_in_opt_cset(_num_optional_regions++); 145 } 146 147 void G1CollectionSet::start_incremental_building() { 148 assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set."); 149 assert(_inc_build_state == Inactive, "Precondition"); 150 151 _inc_bytes_used_before = 0; 152 153 _inc_recorded_rs_length = 0; 154 _inc_recorded_rs_length_diff = 0; 155 _inc_predicted_non_copy_time_ms = 0.0; 156 _inc_predicted_non_copy_time_ms_diff = 0.0; 157 158 update_incremental_marker(); 159 } 160 161 void G1CollectionSet::finalize_incremental_building() { 162 assert(_inc_build_state == Active, "Precondition"); 163 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint"); 164 165 // The two "main" fields, _inc_recorded_rs_length and 166 // _inc_predicted_non_copy_time_ms, are updated by the thread 167 // that adds a new region to the CSet. Further updates by the 168 // concurrent refinement thread that samples the young RSet lengths 169 // are accumulated in the *_diff fields. Here we add the diffs to 170 // the "main" fields. 171 172 _inc_recorded_rs_length += _inc_recorded_rs_length_diff; 173 _inc_predicted_non_copy_time_ms += _inc_predicted_non_copy_time_ms_diff; 174 175 _inc_recorded_rs_length_diff = 0; 176 _inc_predicted_non_copy_time_ms_diff = 0.0; 177 } 178 179 void G1CollectionSet::clear() { 180 assert_at_safepoint_on_vm_thread(); 181 _collection_set_cur_length = 0; 182 } 183 184 void G1CollectionSet::iterate(HeapRegionClosure* cl) const { 185 size_t len = _collection_set_cur_length; 186 OrderAccess::loadload(); 187 188 for (uint i = 0; i < len; i++) { 189 HeapRegion* r = _g1h->region_at(_collection_set_regions[i]); 190 bool result = cl->do_heap_region(r); 191 if (result) { 192 cl->set_incomplete(); 193 return; 194 } 195 } 196 } 197 198 void G1CollectionSet::iterate_optional(HeapRegionClosure* cl) const { 199 assert_at_safepoint(); 200 201 for (uint i = 0; i < _num_optional_regions; i++) { 202 HeapRegion* r = _candidates->at(i); 203 bool result = cl->do_heap_region(r); 204 guarantee(!result, "Must not cancel iteration"); 205 } 206 } 207 208 void G1CollectionSet::iterate_incremental_part_from(HeapRegionClosure* cl, 209 HeapRegionClaimer* hr_claimer, 210 uint worker_id, 211 uint total_workers) const { 212 assert_at_safepoint(); 213 214 size_t len = increment_length(); 215 if (len == 0) { 216 return; 217 } 218 219 size_t start_pos = (worker_id * len) / total_workers; 220 size_t cur_pos = start_pos; 221 222 do { 223 uint region_idx = _collection_set_regions[cur_pos + _inc_part_start]; 224 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) { 225 HeapRegion* r = _g1h->region_at(region_idx); 226 bool result = cl->do_heap_region(r); 227 guarantee(!result, "Must not cancel iteration"); 228 } 229 230 cur_pos++; 231 if (cur_pos == len) { 232 cur_pos = 0; 233 } 234 } while (cur_pos != start_pos); 235 } 236 237 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr, 238 size_t new_rs_length) { 239 // Update the CSet information that is dependent on the new RS length 240 assert(hr->is_young(), "Precondition"); 241 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint"); 242 243 IncCollectionSetRegionStat* stat = &_inc_collection_set_stats[hr->hrm_index()]; 244 245 size_t old_rs_length = stat->_rs_length; 246 assert(old_rs_length <= new_rs_length, 247 "Remembered set sizes must increase (changed from " SIZE_FORMAT " to " SIZE_FORMAT " region %u type %s)", 248 old_rs_length, new_rs_length, hr->hrm_index(), hr->get_short_type_str()); 249 size_t rs_length_diff = new_rs_length - old_rs_length; 250 stat->_rs_length = new_rs_length; 251 _inc_recorded_rs_length_diff += rs_length_diff; 252 253 double old_non_copy_time = stat->_non_copy_time_ms; 254 double new_non_copy_time = predict_region_non_copy_time_ms(hr); 255 double non_copy_time_ms_diff = new_non_copy_time - old_non_copy_time; 256 257 stat->_non_copy_time_ms = new_non_copy_time; 258 _inc_predicted_non_copy_time_ms_diff += non_copy_time_ms_diff; 259 } 260 261 void G1CollectionSet::add_young_region_common(HeapRegion* hr) { 262 assert(hr->is_young(), "invariant"); 263 assert(_inc_build_state == Active, "Precondition"); 264 265 // This routine is used when: 266 // * adding survivor regions to the incremental cset at the end of an 267 // evacuation pause or 268 // * adding the current allocation region to the incremental cset 269 // when it is retired. 270 // Therefore this routine may be called at a safepoint by the 271 // VM thread, or in-between safepoints by mutator threads (when 272 // retiring the current allocation region) 273 // We need to clear and set the cached recorded/cached collection set 274 // information in the heap region here (before the region gets added 275 // to the collection set). An individual heap region's cached values 276 // are calculated, aggregated with the policy collection set info, 277 // and cached in the heap region here (initially) and (subsequently) 278 // by the Young List sampling code. 279 // Ignore calls to this due to retirement during full gc. 280 281 if (!_g1h->collector_state()->in_full_gc()) { 282 size_t rs_length = hr->rem_set()->occupied(); 283 double non_copy_time = predict_region_non_copy_time_ms(hr); 284 285 // Cache the values we have added to the aggregated information 286 // in the heap region in case we have to remove this region from 287 // the incremental collection set, or it is updated by the 288 // rset sampling code 289 290 IncCollectionSetRegionStat* stat = &_inc_collection_set_stats[hr->hrm_index()]; 291 stat->_rs_length = rs_length; 292 stat->_non_copy_time_ms = non_copy_time; 293 294 _inc_recorded_rs_length += rs_length; 295 _inc_predicted_non_copy_time_ms += non_copy_time; 296 _inc_bytes_used_before += hr->used(); 297 } 298 299 assert(!hr->in_collection_set(), "invariant"); 300 _g1h->register_young_region_with_region_attr(hr); 301 302 // We use UINT_MAX as "invalid" marker in verification. 303 assert(_collection_set_cur_length < (UINT_MAX - 1), 304 "Collection set is too large with " SIZE_FORMAT " entries", _collection_set_cur_length); 305 hr->set_young_index_in_cset((uint)_collection_set_cur_length + 1); 306 307 _collection_set_regions[_collection_set_cur_length] = hr->hrm_index(); 308 // Concurrent readers must observe the store of the value in the array before an 309 // update to the length field. 310 OrderAccess::storestore(); 311 _collection_set_cur_length++; 312 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set larger than maximum allowed."); 313 } 314 315 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) { 316 assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str()); 317 add_young_region_common(hr); 318 } 319 320 void G1CollectionSet::add_eden_region(HeapRegion* hr) { 321 assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str()); 322 add_young_region_common(hr); 323 } 324 325 #ifndef PRODUCT 326 class G1VerifyYoungAgesClosure : public HeapRegionClosure { 327 public: 328 bool _valid; 329 330 G1VerifyYoungAgesClosure() : HeapRegionClosure(), _valid(true) { } 331 332 virtual bool do_heap_region(HeapRegion* r) { 333 guarantee(r->is_young(), "Region must be young but is %s", r->get_type_str()); 334 335 if (!r->has_surv_rate_group()) { 336 log_error(gc, verify)("## encountered young region without surv_rate_group"); 337 _valid = false; 338 } 339 340 if (!r->has_valid_age_in_surv_rate()) { 341 log_error(gc, verify)("## encountered invalid age in young region"); 342 _valid = false; 343 } 344 345 return false; 346 } 347 348 bool valid() const { return _valid; } 349 }; 350 351 bool G1CollectionSet::verify_young_ages() { 352 assert_at_safepoint_on_vm_thread(); 353 354 G1VerifyYoungAgesClosure cl; 355 iterate(&cl); 356 357 if (!cl.valid()) { 358 LogStreamHandle(Error, gc, verify) log; 359 print(&log); 360 } 361 362 return cl.valid(); 363 } 364 365 class G1PrintCollectionSetDetailClosure : public HeapRegionClosure { 366 outputStream* _st; 367 public: 368 G1PrintCollectionSetDetailClosure(outputStream* st) : HeapRegionClosure(), _st(st) { } 369 370 virtual bool do_heap_region(HeapRegion* r) { 371 assert(r->in_collection_set(), "Region %u should be in collection set", r->hrm_index()); 372 _st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d", 373 HR_FORMAT_PARAMS(r), 374 p2i(r->prev_top_at_mark_start()), 375 p2i(r->next_top_at_mark_start()), 376 r->has_surv_rate_group() ? r->age_in_surv_rate_group() : -1); 377 return false; 378 } 379 }; 380 381 void G1CollectionSet::print(outputStream* st) { 382 st->print_cr("\nCollection_set:"); 383 384 G1PrintCollectionSetDetailClosure cl(st); 385 iterate(&cl); 386 } 387 #endif // !PRODUCT 388 389 double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors) { 390 Ticks start_time = Ticks::now(); 391 392 finalize_incremental_building(); 393 394 guarantee(target_pause_time_ms > 0.0, 395 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms); 396 397 size_t pending_cards = _policy->pending_cards_at_gc_start() + _g1h->hot_card_cache()->num_entries(); 398 399 log_trace(gc, ergo, cset)("Start choosing CSet. Pending cards: " SIZE_FORMAT " target pause time: %1.2fms", 400 pending_cards, target_pause_time_ms); 401 402 // The young list is laid with the survivor regions from the previous 403 // pause are appended to the RHS of the young list, i.e. 404 // [Newly Young Regions ++ Survivors from last pause]. 405 406 uint eden_region_length = _g1h->eden_regions_count(); 407 uint survivor_region_length = survivors->length(); 408 init_region_lengths(eden_region_length, survivor_region_length); 409 410 verify_young_cset_indices(); 411 412 // Clear the fields that point to the survivor list - they are all young now. 413 survivors->convert_to_eden(); 414 415 _bytes_used_before = _inc_bytes_used_before; 416 417 // The number of recorded young regions is the incremental 418 // collection set's current size 419 set_recorded_rs_length(_inc_recorded_rs_length); 420 421 double predicted_base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards); 422 double predicted_eden_time = _inc_predicted_non_copy_time_ms + _policy->predict_eden_copy_time_ms(eden_region_length); 423 double remaining_time_ms = MAX2(target_pause_time_ms - (predicted_base_time_ms + predicted_eden_time), 0.0); 424 425 log_trace(gc, ergo, cset)("Added young regions to CSet. Eden: %u regions, Survivors: %u regions, " 426 "predicted eden time: %1.2fms, predicted base time: %1.2fms, target pause time: %1.2fms, remaining time: %1.2fms", 427 eden_region_length, survivor_region_length, 428 predicted_eden_time, predicted_base_time_ms, target_pause_time_ms, remaining_time_ms); 429 430 phase_times()->record_young_cset_choice_time_ms((Ticks::now() - start_time).seconds() * 1000.0); 431 432 return remaining_time_ms; 433 } 434 435 static int compare_region_idx(const uint a, const uint b) { 436 if (a > b) { 437 return 1; 438 } else if (a == b) { 439 return 0; 440 } else { 441 return -1; 442 } 443 } 444 445 void G1CollectionSet::finalize_old_part(double time_remaining_ms) { 446 double non_young_start_time_sec = os::elapsedTime(); 447 448 if (collector_state()->in_mixed_phase()) { 449 candidates()->verify(); 450 451 uint num_initial_old_regions; 452 uint num_optional_old_regions; 453 454 _policy->calculate_old_collection_set_regions(candidates(), 455 time_remaining_ms, 456 num_initial_old_regions, 457 num_optional_old_regions); 458 459 // Prepare initial old regions. 460 move_candidates_to_collection_set(num_initial_old_regions); 461 462 // Prepare optional old regions for evacuation. 463 uint candidate_idx = candidates()->cur_idx(); 464 for (uint i = 0; i < num_optional_old_regions; i++) { 465 add_optional_region(candidates()->at(candidate_idx + i)); 466 } 467 468 candidates()->verify(); 469 } 470 471 stop_incremental_building(); 472 473 double non_young_end_time_sec = os::elapsedTime(); 474 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0); 475 476 QuickSort::sort(_collection_set_regions, _collection_set_cur_length, compare_region_idx, true); 477 } 478 479 void G1CollectionSet::move_candidates_to_collection_set(uint num_old_candidate_regions) { 480 if (num_old_candidate_regions == 0) { 481 return; 482 } 483 uint candidate_idx = candidates()->cur_idx(); 484 for (uint i = 0; i < num_old_candidate_regions; i++) { 485 HeapRegion* r = candidates()->at(candidate_idx + i); 486 // This potentially optional candidate region is going to be an actual collection 487 // set region. Clear cset marker. 488 _g1h->clear_region_attr(r); 489 add_old_region(r); 490 } 491 candidates()->remove(num_old_candidate_regions); 492 493 candidates()->verify(); 494 } 495 496 void G1CollectionSet::finalize_initial_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) { 497 double time_remaining_ms = finalize_young_part(target_pause_time_ms, survivor); 498 finalize_old_part(time_remaining_ms); 499 } 500 501 bool G1CollectionSet::finalize_optional_for_evacuation(double remaining_pause_time) { 502 update_incremental_marker(); 503 504 uint num_selected_regions; 505 _policy->calculate_optional_collection_set_regions(candidates(), 506 _num_optional_regions, 507 remaining_pause_time, 508 num_selected_regions); 509 510 move_candidates_to_collection_set(num_selected_regions); 511 512 _num_optional_regions -= num_selected_regions; 513 514 stop_incremental_building(); 515 516 _g1h->verify_region_attr_remset_update(); 517 518 return num_selected_regions > 0; 519 } 520 521 void G1CollectionSet::abandon_optional_collection_set(G1ParScanThreadStateSet* pss) { 522 for (uint i = 0; i < _num_optional_regions; i++) { 523 HeapRegion* r = candidates()->at(candidates()->cur_idx() + i); 524 pss->record_unused_optional_region(r); 525 // Clear collection set marker and make sure that the remembered set information 526 // is correct as we still need it later. 527 _g1h->clear_region_attr(r); 528 _g1h->register_region_with_region_attr(r); 529 r->clear_index_in_opt_cset(); 530 } 531 free_optional_regions(); 532 533 _g1h->verify_region_attr_remset_update(); 534 } 535 536 #ifdef ASSERT 537 class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure { 538 private: 539 size_t _young_length; 540 uint* _heap_region_indices; 541 public: 542 G1VerifyYoungCSetIndicesClosure(size_t young_length) : HeapRegionClosure(), _young_length(young_length) { 543 _heap_region_indices = NEW_C_HEAP_ARRAY(uint, young_length + 1, mtGC); 544 for (size_t i = 0; i < young_length + 1; i++) { 545 _heap_region_indices[i] = UINT_MAX; 546 } 547 } 548 ~G1VerifyYoungCSetIndicesClosure() { 549 FREE_C_HEAP_ARRAY(int, _heap_region_indices); 550 } 551 552 virtual bool do_heap_region(HeapRegion* r) { 553 const uint idx = r->young_index_in_cset(); 554 555 assert(idx > 0, "Young index must be set for all regions in the incremental collection set but is not for region %u.", r->hrm_index()); 556 assert(idx <= _young_length, "Young cset index %u too large for region %u", idx, r->hrm_index()); 557 558 assert(_heap_region_indices[idx] == UINT_MAX, 559 "Index %d used by multiple regions, first use by region %u, second by region %u", 560 idx, _heap_region_indices[idx], r->hrm_index()); 561 562 _heap_region_indices[idx] = r->hrm_index(); 563 564 return false; 565 } 566 }; 567 568 void G1CollectionSet::verify_young_cset_indices() const { 569 assert_at_safepoint_on_vm_thread(); 570 571 G1VerifyYoungCSetIndicesClosure cl(_collection_set_cur_length); 572 iterate(&cl); 573 } 574 #endif