1 /* 2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #include "precompiled.hpp" 25 #include "memory/allocation.hpp" 26 #include "gc/shenandoah/shenandoahForwarding.hpp" 27 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp" 28 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 29 #include "gc/shenandoah/shenandoahHeapRegion.hpp" 30 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 31 #include "gc/shenandoah/shenandoahTraversalGC.hpp" 32 #include "gc/shared/space.inline.hpp" 33 #include "memory/iterator.inline.hpp" 34 #include "memory/resourceArea.hpp" 35 #include "memory/universe.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "runtime/java.hpp" 38 #include "runtime/mutexLocker.hpp" 39 #include "runtime/os.hpp" 40 #include "runtime/safepoint.hpp" 41 42 size_t ShenandoahHeapRegion::RegionCount = 0; 43 size_t ShenandoahHeapRegion::RegionSizeBytes = 0; 44 size_t ShenandoahHeapRegion::RegionSizeWords = 0; 45 size_t ShenandoahHeapRegion::RegionSizeBytesShift = 0; 46 size_t ShenandoahHeapRegion::RegionSizeWordsShift = 0; 47 size_t ShenandoahHeapRegion::RegionSizeBytesMask = 0; 48 size_t ShenandoahHeapRegion::RegionSizeWordsMask = 0; 49 size_t ShenandoahHeapRegion::HumongousThresholdBytes = 0; 50 size_t ShenandoahHeapRegion::HumongousThresholdWords = 0; 51 size_t ShenandoahHeapRegion::MaxTLABSizeBytes = 0; 52 size_t ShenandoahHeapRegion::MaxTLABSizeWords = 0; 53 54 ShenandoahHeapRegion::PaddedAllocSeqNum ShenandoahHeapRegion::_alloc_seq_num; 55 56 ShenandoahHeapRegion::ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, 57 size_t size_words, size_t index, bool committed) : 58 _heap(heap), 59 _reserved(MemRegion(start, size_words)), 60 _region_number(index), 61 _new_top(NULL), 62 _critical_pins(0), 63 _empty_time(os::elapsedTime()), 64 _state(committed ? _empty_committed : _empty_uncommitted), 65 _tlab_allocs(0), 66 _gclab_allocs(0), 67 _shared_allocs(0), 68 _seqnum_first_alloc_mutator(0), 69 _seqnum_first_alloc_gc(0), 70 _seqnum_last_alloc_mutator(0), 71 _seqnum_last_alloc_gc(0), 72 _live_data(0) { 73 74 ContiguousSpace::initialize(_reserved, true, committed); 75 } 76 77 size_t ShenandoahHeapRegion::region_number() const { 78 return _region_number; 79 } 80 81 void ShenandoahHeapRegion::report_illegal_transition(const char *method) { 82 ResourceMark rm; 83 stringStream ss; 84 ss.print("Illegal region state transition from \"%s\", at %s\n ", region_state_to_string(_state), method); 85 print_on(&ss); 86 fatal("%s", ss.as_string()); 87 } 88 89 void ShenandoahHeapRegion::make_regular_allocation() { 90 _heap->assert_heaplock_owned_by_current_thread(); 91 92 switch (_state) { 93 case _empty_uncommitted: 94 do_commit(); 95 case _empty_committed: 96 _state = _regular; 97 case _regular: 98 case _pinned: 99 return; 100 default: 101 report_illegal_transition("regular allocation"); 102 } 103 } 104 105 void ShenandoahHeapRegion::make_regular_bypass() { 106 _heap->assert_heaplock_owned_by_current_thread(); 107 assert (_heap->is_full_gc_in_progress() || _heap->is_degenerated_gc_in_progress(), 108 "only for full or degen GC"); 109 110 switch (_state) { 111 case _empty_uncommitted: 112 do_commit(); 113 case _empty_committed: 114 case _cset: 115 case _humongous_start: 116 case _humongous_cont: 117 _state = _regular; 118 return; 119 case _pinned_cset: 120 _state = _pinned; 121 return; 122 case _regular: 123 case _pinned: 124 return; 125 default: 126 report_illegal_transition("regular bypass"); 127 } 128 } 129 130 void ShenandoahHeapRegion::make_humongous_start() { 131 _heap->assert_heaplock_owned_by_current_thread(); 132 switch (_state) { 133 case _empty_uncommitted: 134 do_commit(); 135 case _empty_committed: 136 _state = _humongous_start; 137 return; 138 default: 139 report_illegal_transition("humongous start allocation"); 140 } 141 } 142 143 void ShenandoahHeapRegion::make_humongous_start_bypass() { 144 _heap->assert_heaplock_owned_by_current_thread(); 145 assert (_heap->is_full_gc_in_progress(), "only for full GC"); 146 147 switch (_state) { 148 case _empty_committed: 149 case _regular: 150 case _humongous_start: 151 case _humongous_cont: 152 _state = _humongous_start; 153 return; 154 default: 155 report_illegal_transition("humongous start bypass"); 156 } 157 } 158 159 void ShenandoahHeapRegion::make_humongous_cont() { 160 _heap->assert_heaplock_owned_by_current_thread(); 161 switch (_state) { 162 case _empty_uncommitted: 163 do_commit(); 164 case _empty_committed: 165 _state = _humongous_cont; 166 return; 167 default: 168 report_illegal_transition("humongous continuation allocation"); 169 } 170 } 171 172 void ShenandoahHeapRegion::make_humongous_cont_bypass() { 173 _heap->assert_heaplock_owned_by_current_thread(); 174 assert (_heap->is_full_gc_in_progress(), "only for full GC"); 175 176 switch (_state) { 177 case _empty_committed: 178 case _regular: 179 case _humongous_start: 180 case _humongous_cont: 181 _state = _humongous_cont; 182 return; 183 default: 184 report_illegal_transition("humongous continuation bypass"); 185 } 186 } 187 188 void ShenandoahHeapRegion::make_pinned() { 189 _heap->assert_heaplock_owned_by_current_thread(); 190 switch (_state) { 191 case _regular: 192 assert (_critical_pins == 0, "sanity"); 193 _state = _pinned; 194 case _pinned_cset: 195 case _pinned: 196 _critical_pins++; 197 return; 198 case _humongous_start: 199 assert (_critical_pins == 0, "sanity"); 200 _state = _pinned_humongous_start; 201 case _pinned_humongous_start: 202 _critical_pins++; 203 return; 204 case _cset: 205 guarantee(_heap->cancelled_gc(), "only valid when evac has been cancelled"); 206 assert (_critical_pins == 0, "sanity"); 207 _state = _pinned_cset; 208 _critical_pins++; 209 return; 210 default: 211 report_illegal_transition("pinning"); 212 } 213 } 214 215 void ShenandoahHeapRegion::make_unpinned() { 216 _heap->assert_heaplock_owned_by_current_thread(); 217 switch (_state) { 218 case _pinned: 219 assert (_critical_pins > 0, "sanity"); 220 _critical_pins--; 221 if (_critical_pins == 0) { 222 _state = _regular; 223 } 224 return; 225 case _regular: 226 case _humongous_start: 227 assert (_critical_pins == 0, "sanity"); 228 return; 229 case _pinned_cset: 230 guarantee(_heap->cancelled_gc(), "only valid when evac has been cancelled"); 231 assert (_critical_pins > 0, "sanity"); 232 _critical_pins--; 233 if (_critical_pins == 0) { 234 _state = _cset; 235 } 236 return; 237 case _pinned_humongous_start: 238 assert (_critical_pins > 0, "sanity"); 239 _critical_pins--; 240 if (_critical_pins == 0) { 241 _state = _humongous_start; 242 } 243 return; 244 default: 245 report_illegal_transition("unpinning"); 246 } 247 } 248 249 void ShenandoahHeapRegion::make_cset() { 250 _heap->assert_heaplock_owned_by_current_thread(); 251 switch (_state) { 252 case _regular: 253 _state = _cset; 254 case _cset: 255 return; 256 default: 257 report_illegal_transition("cset"); 258 } 259 } 260 261 void ShenandoahHeapRegion::make_trash() { 262 _heap->assert_heaplock_owned_by_current_thread(); 263 switch (_state) { 264 case _cset: 265 // Reclaiming cset regions 266 case _humongous_start: 267 case _humongous_cont: 268 // Reclaiming humongous regions 269 case _regular: 270 // Immediate region reclaim 271 _state = _trash; 272 return; 273 default: 274 report_illegal_transition("trashing"); 275 } 276 } 277 278 void ShenandoahHeapRegion::make_trash_immediate() { 279 make_trash(); 280 281 // On this path, we know there are no marked objects in the region, 282 // tell marking context about it to bypass bitmap resets. 283 _heap->complete_marking_context()->reset_top_bitmap(this); 284 } 285 286 void ShenandoahHeapRegion::make_empty() { 287 _heap->assert_heaplock_owned_by_current_thread(); 288 switch (_state) { 289 case _trash: 290 _state = _empty_committed; 291 _empty_time = os::elapsedTime(); 292 return; 293 default: 294 report_illegal_transition("emptying"); 295 } 296 } 297 298 void ShenandoahHeapRegion::make_uncommitted() { 299 _heap->assert_heaplock_owned_by_current_thread(); 300 switch (_state) { 301 case _empty_committed: 302 do_uncommit(); 303 _state = _empty_uncommitted; 304 return; 305 default: 306 report_illegal_transition("uncommiting"); 307 } 308 } 309 310 void ShenandoahHeapRegion::make_committed_bypass() { 311 _heap->assert_heaplock_owned_by_current_thread(); 312 assert (_heap->is_full_gc_in_progress(), "only for full GC"); 313 314 switch (_state) { 315 case _empty_uncommitted: 316 do_commit(); 317 _state = _empty_committed; 318 return; 319 default: 320 report_illegal_transition("commit bypass"); 321 } 322 } 323 324 void ShenandoahHeapRegion::clear_live_data() { 325 OrderAccess::release_store_fence<size_t>(&_live_data, 0); 326 } 327 328 void ShenandoahHeapRegion::reset_alloc_metadata() { 329 _tlab_allocs = 0; 330 _gclab_allocs = 0; 331 _shared_allocs = 0; 332 _seqnum_first_alloc_mutator = 0; 333 _seqnum_last_alloc_mutator = 0; 334 _seqnum_first_alloc_gc = 0; 335 _seqnum_last_alloc_gc = 0; 336 } 337 338 void ShenandoahHeapRegion::reset_alloc_metadata_to_shared() { 339 if (used() > 0) { 340 _tlab_allocs = 0; 341 _gclab_allocs = 0; 342 _shared_allocs = used() >> LogHeapWordSize; 343 uint64_t next = _alloc_seq_num.value++; 344 _seqnum_first_alloc_mutator = next; 345 _seqnum_last_alloc_mutator = next; 346 _seqnum_first_alloc_gc = 0; 347 _seqnum_last_alloc_gc = 0; 348 } else { 349 reset_alloc_metadata(); 350 } 351 } 352 353 size_t ShenandoahHeapRegion::get_shared_allocs() const { 354 return _shared_allocs * HeapWordSize; 355 } 356 357 size_t ShenandoahHeapRegion::get_tlab_allocs() const { 358 return _tlab_allocs * HeapWordSize; 359 } 360 361 size_t ShenandoahHeapRegion::get_gclab_allocs() const { 362 return _gclab_allocs * HeapWordSize; 363 } 364 365 void ShenandoahHeapRegion::set_live_data(size_t s) { 366 assert(Thread::current()->is_VM_thread(), "by VM thread"); 367 _live_data = (s >> LogHeapWordSize); 368 } 369 370 size_t ShenandoahHeapRegion::get_live_data_words() const { 371 return OrderAccess::load_acquire(&_live_data); 372 } 373 374 size_t ShenandoahHeapRegion::get_live_data_bytes() const { 375 return get_live_data_words() * HeapWordSize; 376 } 377 378 bool ShenandoahHeapRegion::has_live() const { 379 return get_live_data_words() != 0; 380 } 381 382 size_t ShenandoahHeapRegion::garbage() const { 383 assert(used() >= get_live_data_bytes(), "Live Data must be a subset of used() live: " SIZE_FORMAT " used: " SIZE_FORMAT, 384 get_live_data_bytes(), used()); 385 386 size_t result = used() - get_live_data_bytes(); 387 return result; 388 } 389 390 void ShenandoahHeapRegion::print_on(outputStream* st) const { 391 st->print("|"); 392 st->print(SIZE_FORMAT_W(5), this->_region_number); 393 394 switch (_state) { 395 case _empty_uncommitted: 396 st->print("|EU "); 397 break; 398 case _empty_committed: 399 st->print("|EC "); 400 break; 401 case _regular: 402 st->print("|R "); 403 break; 404 case _humongous_start: 405 st->print("|H "); 406 break; 407 case _pinned_humongous_start: 408 st->print("|HP "); 409 break; 410 case _humongous_cont: 411 st->print("|HC "); 412 break; 413 case _cset: 414 st->print("|CS "); 415 break; 416 case _trash: 417 st->print("|T "); 418 break; 419 case _pinned: 420 st->print("|P "); 421 break; 422 case _pinned_cset: 423 st->print("|CSP"); 424 break; 425 default: 426 ShouldNotReachHere(); 427 } 428 st->print("|BTE " INTPTR_FORMAT_W(12) ", " INTPTR_FORMAT_W(12) ", " INTPTR_FORMAT_W(12), 429 p2i(bottom()), p2i(top()), p2i(end())); 430 st->print("|TAMS " INTPTR_FORMAT_W(12), 431 p2i(_heap->marking_context()->top_at_mark_start(const_cast<ShenandoahHeapRegion*>(this)))); 432 st->print("|U " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used())); 433 st->print("|T " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_tlab_allocs()), proper_unit_for_byte_size(get_tlab_allocs())); 434 st->print("|G " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_gclab_allocs()), proper_unit_for_byte_size(get_gclab_allocs())); 435 st->print("|S " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_shared_allocs()), proper_unit_for_byte_size(get_shared_allocs())); 436 st->print("|L " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_live_data_bytes()), proper_unit_for_byte_size(get_live_data_bytes())); 437 st->print("|CP " SIZE_FORMAT_W(3), _critical_pins); 438 st->print("|SN " UINT64_FORMAT_X_W(12) ", " UINT64_FORMAT_X_W(8) ", " UINT64_FORMAT_X_W(8) ", " UINT64_FORMAT_X_W(8), 439 seqnum_first_alloc_mutator(), seqnum_last_alloc_mutator(), 440 seqnum_first_alloc_gc(), seqnum_last_alloc_gc()); 441 st->cr(); 442 } 443 444 void ShenandoahHeapRegion::oop_iterate(OopIterateClosure* blk) { 445 if (!is_active()) return; 446 if (is_humongous()) { 447 oop_iterate_humongous(blk); 448 } else { 449 oop_iterate_objects(blk); 450 } 451 } 452 453 void ShenandoahHeapRegion::oop_iterate_objects(OopIterateClosure* blk) { 454 assert(! is_humongous(), "no humongous region here"); 455 HeapWord* obj_addr = bottom() + ShenandoahForwarding::word_size(); 456 HeapWord* t = top(); 457 // Could call objects iterate, but this is easier. 458 while (obj_addr < t) { 459 oop obj = oop(obj_addr); 460 obj_addr += obj->oop_iterate_size(blk) + ShenandoahForwarding::word_size(); 461 } 462 } 463 464 void ShenandoahHeapRegion::oop_iterate_humongous(OopIterateClosure* blk) { 465 assert(is_humongous(), "only humongous region here"); 466 // Find head. 467 ShenandoahHeapRegion* r = humongous_start_region(); 468 assert(r->is_humongous_start(), "need humongous head here"); 469 oop obj = oop(r->bottom() + ShenandoahForwarding::word_size()); 470 obj->oop_iterate(blk, MemRegion(bottom(), top())); 471 } 472 473 ShenandoahHeapRegion* ShenandoahHeapRegion::humongous_start_region() const { 474 assert(is_humongous(), "Must be a part of the humongous region"); 475 size_t reg_num = region_number(); 476 ShenandoahHeapRegion* r = const_cast<ShenandoahHeapRegion*>(this); 477 while (!r->is_humongous_start()) { 478 assert(reg_num > 0, "Sanity"); 479 reg_num --; 480 r = _heap->get_region(reg_num); 481 assert(r->is_humongous(), "Must be a part of the humongous region"); 482 } 483 assert(r->is_humongous_start(), "Must be"); 484 return r; 485 } 486 487 void ShenandoahHeapRegion::recycle() { 488 ContiguousSpace::clear(false); 489 if (ZapUnusedHeapArea) { 490 ContiguousSpace::mangle_unused_area_complete(); 491 } 492 clear_live_data(); 493 494 reset_alloc_metadata(); 495 496 _heap->marking_context()->reset_top_at_mark_start(this); 497 498 make_empty(); 499 } 500 501 HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const { 502 assert(MemRegion(bottom(), end()).contains(p), 503 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 504 p2i(p), p2i(bottom()), p2i(end())); 505 if (p >= top()) { 506 return top(); 507 } else { 508 HeapWord* last = bottom() + ShenandoahForwarding::word_size(); 509 HeapWord* cur = last; 510 while (cur <= p) { 511 last = cur; 512 cur += oop(cur)->size() + ShenandoahForwarding::word_size(); 513 } 514 shenandoah_assert_correct(NULL, oop(last)); 515 return last; 516 } 517 } 518 519 void ShenandoahHeapRegion::setup_sizes(size_t initial_heap_size, size_t max_heap_size) { 520 // Absolute minimums we should not ever break. 521 static const size_t MIN_REGION_SIZE = 256*K; 522 523 if (FLAG_IS_DEFAULT(ShenandoahMinRegionSize)) { 524 FLAG_SET_DEFAULT(ShenandoahMinRegionSize, MIN_REGION_SIZE); 525 } 526 527 size_t region_size; 528 if (FLAG_IS_DEFAULT(ShenandoahHeapRegionSize)) { 529 if (ShenandoahMinRegionSize > initial_heap_size / MIN_NUM_REGIONS) { 530 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number " 531 "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "K).", 532 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahMinRegionSize/K); 533 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message); 534 } 535 if (ShenandoahMinRegionSize < MIN_REGION_SIZE) { 536 err_msg message("" SIZE_FORMAT "K should not be lower than minimum region size (" SIZE_FORMAT "K).", 537 ShenandoahMinRegionSize/K, MIN_REGION_SIZE/K); 538 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message); 539 } 540 if (ShenandoahMinRegionSize < MinTLABSize) { 541 err_msg message("" SIZE_FORMAT "K should not be lower than TLAB size size (" SIZE_FORMAT "K).", 542 ShenandoahMinRegionSize/K, MinTLABSize/K); 543 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message); 544 } 545 if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) { 546 err_msg message("" SIZE_FORMAT "K should not be lower than min region size (" SIZE_FORMAT "K).", 547 ShenandoahMaxRegionSize/K, MIN_REGION_SIZE/K); 548 vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message); 549 } 550 if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) { 551 err_msg message("Minimum (" SIZE_FORMAT "K) should be larger than maximum (" SIZE_FORMAT "K).", 552 ShenandoahMinRegionSize/K, ShenandoahMaxRegionSize/K); 553 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message); 554 } 555 556 // We rapidly expand to max_heap_size in most scenarios, so that is the measure 557 // for usual heap sizes. Do not depend on initial_heap_size here. 558 region_size = max_heap_size / ShenandoahTargetNumRegions; 559 560 // Now make sure that we don't go over or under our limits. 561 region_size = MAX2(ShenandoahMinRegionSize, region_size); 562 region_size = MIN2(ShenandoahMaxRegionSize, region_size); 563 564 } else { 565 if (ShenandoahHeapRegionSize > initial_heap_size / MIN_NUM_REGIONS) { 566 err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number " 567 "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "K).", 568 initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahHeapRegionSize/K); 569 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message); 570 } 571 if (ShenandoahHeapRegionSize < ShenandoahMinRegionSize) { 572 err_msg message("Heap region size (" SIZE_FORMAT "K) should be larger than min region size (" SIZE_FORMAT "K).", 573 ShenandoahHeapRegionSize/K, ShenandoahMinRegionSize/K); 574 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message); 575 } 576 if (ShenandoahHeapRegionSize > ShenandoahMaxRegionSize) { 577 err_msg message("Heap region size (" SIZE_FORMAT "K) should be lower than max region size (" SIZE_FORMAT "K).", 578 ShenandoahHeapRegionSize/K, ShenandoahMaxRegionSize/K); 579 vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message); 580 } 581 region_size = ShenandoahHeapRegionSize; 582 } 583 584 // Make sure region size is at least one large page, if enabled. 585 // Otherwise, uncommitting one region may falsely uncommit the adjacent 586 // regions too. 587 // Also see shenandoahArguments.cpp, where it handles UseLargePages. 588 if (UseLargePages && ShenandoahUncommit) { 589 region_size = MAX2(region_size, os::large_page_size()); 590 } 591 592 int region_size_log = log2_long((jlong) region_size); 593 // Recalculate the region size to make sure it's a power of 594 // 2. This means that region_size is the largest power of 2 that's 595 // <= what we've calculated so far. 596 region_size = size_t(1) << region_size_log; 597 598 // Now, set up the globals. 599 guarantee(RegionSizeBytesShift == 0, "we should only set it once"); 600 RegionSizeBytesShift = (size_t)region_size_log; 601 602 guarantee(RegionSizeWordsShift == 0, "we should only set it once"); 603 RegionSizeWordsShift = RegionSizeBytesShift - LogHeapWordSize; 604 605 guarantee(RegionSizeBytes == 0, "we should only set it once"); 606 RegionSizeBytes = region_size; 607 RegionSizeWords = RegionSizeBytes >> LogHeapWordSize; 608 assert (RegionSizeWords*HeapWordSize == RegionSizeBytes, "sanity"); 609 610 guarantee(RegionSizeWordsMask == 0, "we should only set it once"); 611 RegionSizeWordsMask = RegionSizeWords - 1; 612 613 guarantee(RegionSizeBytesMask == 0, "we should only set it once"); 614 RegionSizeBytesMask = RegionSizeBytes - 1; 615 616 guarantee(RegionCount == 0, "we should only set it once"); 617 RegionCount = max_heap_size / RegionSizeBytes; 618 guarantee(RegionCount >= MIN_NUM_REGIONS, "Should have at least minimum regions"); 619 620 guarantee(HumongousThresholdWords == 0, "we should only set it once"); 621 HumongousThresholdWords = RegionSizeWords * ShenandoahHumongousThreshold / 100; 622 HumongousThresholdWords = align_down(HumongousThresholdWords, MinObjAlignment); 623 assert (HumongousThresholdWords <= RegionSizeWords, "sanity"); 624 625 guarantee(HumongousThresholdBytes == 0, "we should only set it once"); 626 HumongousThresholdBytes = HumongousThresholdWords * HeapWordSize; 627 assert (HumongousThresholdBytes <= RegionSizeBytes, "sanity"); 628 629 // The rationale for trimming the TLAB sizes has to do with the raciness in 630 // TLAB allocation machinery. It may happen that TLAB sizing policy polls Shenandoah 631 // about next free size, gets the answer for region #N, goes away for a while, then 632 // tries to allocate in region #N, and fail because some other thread have claimed part 633 // of the region #N, and then the freeset allocation code has to retire the region #N, 634 // before moving the allocation to region #N+1. 635 // 636 // The worst case realizes when "answer" is "region size", which means it could 637 // prematurely retire an entire region. Having smaller TLABs does not fix that 638 // completely, but reduces the probability of too wasteful region retirement. 639 // With current divisor, we will waste no more than 1/8 of region size in the worst 640 // case. This also has a secondary effect on collection set selection: even under 641 // the race, the regions would be at least 7/8 used, which allows relying on 642 // "used" - "live" for cset selection. Otherwise, we can get the fragmented region 643 // below the garbage threshold that would never be considered for collection. 644 // 645 // The whole thing is mitigated if Elastic TLABs are enabled. 646 // 647 guarantee(MaxTLABSizeWords == 0, "we should only set it once"); 648 MaxTLABSizeWords = MIN2(ShenandoahElasticTLAB ? RegionSizeWords : (RegionSizeWords / 8), HumongousThresholdWords); 649 MaxTLABSizeWords = align_down(MaxTLABSizeWords, MinObjAlignment); 650 651 guarantee(MaxTLABSizeBytes == 0, "we should only set it once"); 652 MaxTLABSizeBytes = MaxTLABSizeWords * HeapWordSize; 653 assert (MaxTLABSizeBytes > MinTLABSize, "should be larger"); 654 655 log_info(gc, init)("Regions: " SIZE_FORMAT " x " SIZE_FORMAT "%s", 656 RegionCount, byte_size_in_proper_unit(RegionSizeBytes), proper_unit_for_byte_size(RegionSizeBytes)); 657 log_info(gc, init)("Humongous object threshold: " SIZE_FORMAT "%s", 658 byte_size_in_proper_unit(HumongousThresholdBytes), proper_unit_for_byte_size(HumongousThresholdBytes)); 659 log_info(gc, init)("Max TLAB size: " SIZE_FORMAT "%s", 660 byte_size_in_proper_unit(MaxTLABSizeBytes), proper_unit_for_byte_size(MaxTLABSizeBytes)); 661 } 662 663 void ShenandoahHeapRegion::do_commit() { 664 if (!_heap->is_heap_region_special() && !os::commit_memory((char *) _reserved.start(), _reserved.byte_size(), false)) { 665 report_java_out_of_memory("Unable to commit region"); 666 } 667 if (!_heap->commit_bitmap_slice(this)) { 668 report_java_out_of_memory("Unable to commit bitmaps for region"); 669 } 670 _heap->increase_committed(ShenandoahHeapRegion::region_size_bytes()); 671 } 672 673 void ShenandoahHeapRegion::do_uncommit() { 674 if (!_heap->is_heap_region_special() && !os::uncommit_memory((char *) _reserved.start(), _reserved.byte_size())) { 675 report_java_out_of_memory("Unable to uncommit region"); 676 } 677 if (!_heap->uncommit_bitmap_slice(this)) { 678 report_java_out_of_memory("Unable to uncommit bitmaps for region"); 679 } 680 _heap->decrease_committed(ShenandoahHeapRegion::region_size_bytes()); 681 }