1 /*
   2  * Copyright (c) 2001, 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/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc/g1/heapRegion.hpp"
  29 #include "gc/g1/heapRegionManager.inline.hpp"
  30 #include "gc/g1/heapRegionSet.inline.hpp"
  31 #include "memory/allocation.hpp"
  32 
  33 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
  34                                G1RegionToSpaceMapper* prev_bitmap,
  35                                G1RegionToSpaceMapper* next_bitmap,
  36                                G1RegionToSpaceMapper* bot,
  37                                G1RegionToSpaceMapper* cardtable,
  38                                G1RegionToSpaceMapper* card_counts) {
  39   _allocated_heapregions_length = 0;
  40 
  41   _heap_mapper = heap_storage;
  42 
  43   _prev_bitmap_mapper = prev_bitmap;
  44   _next_bitmap_mapper = next_bitmap;
  45 
  46   _bot_mapper = bot;
  47   _cardtable_mapper = cardtable;
  48 
  49   _card_counts_mapper = card_counts;
  50 
  51   MemRegion reserved = heap_storage->reserved();
  52   _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
  53 
  54   _available_map.resize(_regions.length(), false);
  55   _available_map.clear();
  56 }
  57 
  58 bool HeapRegionManager::is_available(uint region) const {
  59   return _available_map.at(region);
  60 }
  61 
  62 #ifdef ASSERT
  63 bool HeapRegionManager::is_free(HeapRegion* hr) const {
  64   return _free_list.contains(hr);
  65 }
  66 #endif
  67 
  68 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
  69   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  70   HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
  71   MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
  72   assert(reserved().contains(mr), "invariant");
  73   return g1h->new_heap_region(hrm_index, mr);
  74 }
  75 
  76 void HeapRegionManager::commit_regions(uint index, size_t num_regions) {
  77   guarantee(num_regions > 0, "Must commit more than zero regions");
  78   guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
  79 
  80   _num_committed += (uint)num_regions;
  81 
  82   _heap_mapper->commit_regions(index, num_regions);
  83 
  84   // Also commit auxiliary data
  85   _prev_bitmap_mapper->commit_regions(index, num_regions);
  86   _next_bitmap_mapper->commit_regions(index, num_regions);
  87 
  88   _bot_mapper->commit_regions(index, num_regions);
  89   _cardtable_mapper->commit_regions(index, num_regions);
  90 
  91   _card_counts_mapper->commit_regions(index, num_regions);
  92 }
  93 
  94 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
  95   guarantee(num_regions >= 1, err_msg("Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start));
  96   guarantee(_num_committed >= num_regions, "pre-condition");
  97 
  98   // Print before uncommitting.
  99   if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
 100     for (uint i = start; i < start + num_regions; i++) {
 101       HeapRegion* hr = at(i);
 102       G1CollectedHeap::heap()->hr_printer()->uncommit(hr->bottom(), hr->end());
 103     }
 104   }
 105 
 106   _num_committed -= (uint)num_regions;
 107 
 108   _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
 109   _heap_mapper->uncommit_regions(start, num_regions);
 110 
 111   // Also uncommit auxiliary data
 112   _prev_bitmap_mapper->uncommit_regions(start, num_regions);
 113   _next_bitmap_mapper->uncommit_regions(start, num_regions);
 114 
 115   _bot_mapper->uncommit_regions(start, num_regions);
 116   _cardtable_mapper->uncommit_regions(start, num_regions);
 117 
 118   _card_counts_mapper->uncommit_regions(start, num_regions);
 119 }
 120 
 121 void HeapRegionManager::make_regions_available(uint start, uint num_regions) {
 122   guarantee(num_regions > 0, "No point in calling this for zero regions");
 123   commit_regions(start, num_regions);
 124   for (uint i = start; i < start + num_regions; i++) {
 125     if (_regions.get_by_index(i) == NULL) {
 126       HeapRegion* new_hr = new_heap_region(i);
 127       _regions.set_by_index(i, new_hr);
 128       _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
 129     }
 130   }
 131 
 132   _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
 133 
 134   for (uint i = start; i < start + num_regions; i++) {
 135     assert(is_available(i), err_msg("Just made region %u available but is apparently not.", i));
 136     HeapRegion* hr = at(i);
 137     if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
 138       G1CollectedHeap::heap()->hr_printer()->commit(hr->bottom(), hr->end());
 139     }
 140     HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
 141     MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
 142 
 143     hr->initialize(mr);
 144     insert_into_free_list(at(i));
 145   }
 146 }
 147 
 148 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
 149   size_t used_sz =
 150     _prev_bitmap_mapper->committed_size() +
 151     _next_bitmap_mapper->committed_size() +
 152     _bot_mapper->committed_size() +
 153     _cardtable_mapper->committed_size() +
 154     _card_counts_mapper->committed_size();
 155 
 156   size_t committed_sz =
 157     _prev_bitmap_mapper->reserved_size() +
 158     _next_bitmap_mapper->reserved_size() +
 159     _bot_mapper->reserved_size() +
 160     _cardtable_mapper->reserved_size() +
 161     _card_counts_mapper->reserved_size();
 162 
 163   return MemoryUsage(0, used_sz, committed_sz, committed_sz);
 164 }
 165 
 166 uint HeapRegionManager::expand_by(uint num_regions) {
 167   return expand_at(0, num_regions);
 168 }
 169 
 170 uint HeapRegionManager::expand_at(uint start, uint num_regions) {
 171   if (num_regions == 0) {
 172     return 0;
 173   }
 174 
 175   uint cur = start;
 176   uint idx_last_found = 0;
 177   uint num_last_found = 0;
 178 
 179   uint expanded = 0;
 180 
 181   while (expanded < num_regions &&
 182          (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
 183     uint to_expand = MIN2(num_regions - expanded, num_last_found);
 184     make_regions_available(idx_last_found, to_expand);
 185     expanded += to_expand;
 186     cur = idx_last_found + num_last_found + 1;
 187   }
 188 
 189   verify_optional();
 190   return expanded;
 191 }
 192 
 193 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
 194   uint found = 0;
 195   size_t length_found = 0;
 196   uint cur = 0;
 197 
 198   while (length_found < num && cur < max_length()) {
 199     HeapRegion* hr = _regions.get_by_index(cur);
 200     if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
 201       // This region is a potential candidate for allocation into.
 202       length_found++;
 203     } else {
 204       // This region is not a candidate. The next region is the next possible one.
 205       found = cur + 1;
 206       length_found = 0;
 207     }
 208     cur++;
 209   }
 210 
 211   if (length_found == num) {
 212     for (uint i = found; i < (found + num); i++) {
 213       HeapRegion* hr = _regions.get_by_index(i);
 214       // sanity check
 215       guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
 216                 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
 217                         " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));
 218     }
 219     return found;
 220   } else {
 221     return G1_NO_HRM_INDEX;
 222   }
 223 }
 224 
 225 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
 226   guarantee(r != NULL, "Start region must be a valid region");
 227   guarantee(is_available(r->hrm_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrm_index()));
 228   for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
 229     HeapRegion* hr = _regions.get_by_index(i);
 230     if (is_available(i)) {
 231       return hr;
 232     }
 233   }
 234   return NULL;
 235 }
 236 
 237 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
 238   uint len = max_length();
 239 
 240   for (uint i = 0; i < len; i++) {
 241     if (!is_available(i)) {
 242       continue;
 243     }
 244     guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));
 245     bool res = blk->doHeapRegion(at(i));
 246     if (res) {
 247       blk->incomplete();
 248       return;
 249     }
 250   }
 251 }
 252 
 253 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
 254   guarantee(res_idx != NULL, "checking");
 255   guarantee(start_idx <= (max_length() + 1), "checking");
 256 
 257   uint num_regions = 0;
 258 
 259   uint cur = start_idx;
 260   while (cur < max_length() && is_available(cur)) {
 261     cur++;
 262   }
 263   if (cur == max_length()) {
 264     return num_regions;
 265   }
 266   *res_idx = cur;
 267   while (cur < max_length() && !is_available(cur)) {
 268     cur++;
 269   }
 270   num_regions = cur - *res_idx;
 271 #ifdef ASSERT
 272   for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
 273     assert(!is_available(i), "just checking");
 274   }
 275   assert(cur == max_length() || num_regions == 0 || is_available(cur),
 276          err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
 277 #endif
 278   return num_regions;
 279 }
 280 
 281 uint HeapRegionManager::find_highest_free(bool* expanded) {
 282   // Loop downwards from the highest region index, looking for an
 283   // entry which is either free or not yet committed.  If not yet
 284   // committed, expand_at that index.
 285   uint curr = max_length() - 1;
 286   while (true) {
 287     HeapRegion *hr = _regions.get_by_index(curr);
 288     if (hr == NULL) {
 289       uint res = expand_at(curr, 1);
 290       if (res == 1) {
 291         *expanded = true;
 292         return curr;
 293       }
 294     } else {
 295       if (hr->is_free()) {
 296         *expanded = false;
 297         return curr;
 298       }
 299     }
 300     if (curr == 0) {
 301       return G1_NO_HRM_INDEX;
 302     }
 303     curr--;
 304   }
 305 }
 306 
 307 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count) {
 308   size_t commits = 0;
 309   uint start_index = (uint)_regions.get_index_by_address(range.start());
 310   uint last_index = (uint)_regions.get_index_by_address(range.last());
 311 
 312   // Ensure that each G1 region in the range is free, returning false if not.
 313   // Commit those that are not yet available, and keep count.
 314   for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
 315     if (!is_available(curr_index)) {
 316       commits++;
 317       expand_at(curr_index, 1);
 318     }
 319     HeapRegion* curr_region  = _regions.get_by_index(curr_index);
 320     if (!curr_region->is_free()) {
 321       return false;
 322     }
 323   }
 324 
 325   allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
 326   *commit_count = commits;
 327   return true;
 328 }
 329 
 330 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {
 331   const uint start_index = hrclaimer->start_region_for_worker(worker_id);
 332 
 333   // Every worker will actually look at all regions, skipping over regions that
 334   // are currently not committed.
 335   // This also (potentially) iterates over regions newly allocated during GC. This
 336   // is no problem except for some extra work.
 337   const uint n_regions = hrclaimer->n_regions();
 338   for (uint count = 0; count < n_regions; count++) {
 339     const uint index = (start_index + count) % n_regions;
 340     assert(index < n_regions, "sanity");
 341     // Skip over unavailable regions
 342     if (!is_available(index)) {
 343       continue;
 344     }
 345     HeapRegion* r = _regions.get_by_index(index);
 346     // We'll ignore "continues humongous" regions (we'll process them
 347     // when we come across their corresponding "start humongous"
 348     // region) and regions already claimed.
 349     // However, if the iteration is specified as concurrent, the values for
 350     // is_starts_humongous and is_continues_humongous can not be trusted,
 351     // and we should just blindly iterate over regions regardless of their
 352     // humongous status.
 353     if (hrclaimer->is_region_claimed(index) || (!concurrent && r->is_continues_humongous())) {
 354       continue;
 355     }
 356     // OK, try to claim it
 357     if (!hrclaimer->claim_region(index)) {
 358       continue;
 359     }
 360     // Success!
 361     // As mentioned above, special treatment of humongous regions can only be
 362     // done if we are iterating non-concurrently.
 363     if (!concurrent && r->is_starts_humongous()) {
 364       // If the region is "starts humongous" we'll iterate over its
 365       // "continues humongous" first; in fact we'll do them
 366       // first. The order is important. In one case, calling the
 367       // closure on the "starts humongous" region might de-allocate
 368       // and clear all its "continues humongous" regions and, as a
 369       // result, we might end up processing them twice. So, we'll do
 370       // them first (note: most closures will ignore them anyway) and
 371       // then we'll do the "starts humongous" region.
 372       for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {
 373         HeapRegion* chr = _regions.get_by_index(ch_index);
 374 
 375         assert(chr->is_continues_humongous(), "Must be humongous region");
 376         assert(chr->humongous_start_region() == r,
 377                err_msg("Must work on humongous continuation of the original start region "
 378                        PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
 379         assert(!hrclaimer->is_region_claimed(ch_index),
 380                "Must not have been claimed yet because claiming of humongous continuation first claims the start region");
 381 
 382         // Claim the region so no other worker tries to process the region. When a worker processes a
 383         // starts_humongous region it may also process the associated continues_humongous regions.
 384         // The continues_humongous regions can be changed to free regions. Unless this worker claims
 385         // all of these regions, other workers might try claim and process these newly free regions.
 386         bool claim_result = hrclaimer->claim_region(ch_index);
 387         guarantee(claim_result, "We should always be able to claim the continuesHumongous part of the humongous object");
 388 
 389         bool res2 = blk->doHeapRegion(chr);
 390         if (res2) {
 391           return;
 392         }
 393 
 394         // Right now, this holds (i.e., no closure that actually
 395         // does something with "continues humongous" regions
 396         // clears them). We might have to weaken it in the future,
 397         // but let's leave these two asserts here for extra safety.
 398         assert(chr->is_continues_humongous(), "should still be the case");
 399         assert(chr->humongous_start_region() == r, "sanity");
 400       }
 401     }
 402 
 403     bool res = blk->doHeapRegion(r);
 404     if (res) {
 405       return;
 406     }
 407   }
 408 }
 409 
 410 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
 411   assert(length() > 0, "the region sequence should not be empty");
 412   assert(length() <= _allocated_heapregions_length, "invariant");
 413   assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
 414   assert(num_regions_to_remove < length(), "We should never remove all regions");
 415 
 416   if (num_regions_to_remove == 0) {
 417     return 0;
 418   }
 419 
 420   uint removed = 0;
 421   uint cur = _allocated_heapregions_length - 1;
 422   uint idx_last_found = 0;
 423   uint num_last_found = 0;
 424 
 425   while ((removed < num_regions_to_remove) &&
 426       (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
 427     uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
 428 
 429     shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
 430 
 431     cur = idx_last_found;
 432     removed += to_remove;
 433   }
 434 
 435   verify_optional();
 436 
 437   return removed;
 438 }
 439 
 440 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
 441 #ifdef ASSERT
 442   for (uint i = index; i < (index + num_regions); i++) {
 443     assert(is_available(i), err_msg("Expected available region at index %u", i));
 444     assert(at(i)->is_empty(), err_msg("Expected empty region at index %u", i));
 445     assert(at(i)->is_free(), err_msg("Expected free region at index %u", i));
 446   }
 447 #endif
 448   uncommit_regions(index, num_regions);
 449 }
 450 
 451 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
 452   guarantee(start_idx < _allocated_heapregions_length, "checking");
 453   guarantee(res_idx != NULL, "checking");
 454 
 455   uint num_regions_found = 0;
 456 
 457   jlong cur = start_idx;
 458   while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
 459     cur--;
 460   }
 461   if (cur == -1) {
 462     return num_regions_found;
 463   }
 464   jlong old_cur = cur;
 465   // cur indexes the first empty region
 466   while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
 467     cur--;
 468   }
 469   *res_idx = cur + 1;
 470   num_regions_found = old_cur - cur;
 471 
 472 #ifdef ASSERT
 473   for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
 474     assert(at(i)->is_empty(), "just checking");
 475   }
 476 #endif
 477   return num_regions_found;
 478 }
 479 
 480 void HeapRegionManager::verify() {
 481   guarantee(length() <= _allocated_heapregions_length,
 482             err_msg("invariant: _length: %u _allocated_length: %u",
 483                     length(), _allocated_heapregions_length));
 484   guarantee(_allocated_heapregions_length <= max_length(),
 485             err_msg("invariant: _allocated_length: %u _max_length: %u",
 486                     _allocated_heapregions_length, max_length()));
 487 
 488   bool prev_committed = true;
 489   uint num_committed = 0;
 490   HeapWord* prev_end = heap_bottom();
 491   for (uint i = 0; i < _allocated_heapregions_length; i++) {
 492     if (!is_available(i)) {
 493       prev_committed = false;
 494       continue;
 495     }
 496     num_committed++;
 497     HeapRegion* hr = _regions.get_by_index(i);
 498     guarantee(hr != NULL, err_msg("invariant: i: %u", i));
 499     guarantee(!prev_committed || hr->bottom() == prev_end,
 500               err_msg("invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
 501                       i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));
 502     guarantee(hr->hrm_index() == i,
 503               err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));
 504     // Asserts will fire if i is >= _length
 505     HeapWord* addr = hr->bottom();
 506     guarantee(addr_to_region(addr) == hr, "sanity");
 507     // We cannot check whether the region is part of a particular set: at the time
 508     // this method may be called, we have only completed allocation of the regions,
 509     // but not put into a region set.
 510     prev_committed = true;
 511     if (hr->is_starts_humongous()) {
 512       prev_end = hr->orig_end();
 513     } else {
 514       prev_end = hr->end();
 515     }
 516   }
 517   for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
 518     guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));
 519   }
 520 
 521   guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));
 522   _free_list.verify();
 523 }
 524 
 525 #ifndef PRODUCT
 526 void HeapRegionManager::verify_optional() {
 527   verify();
 528 }
 529 #endif // PRODUCT
 530 
 531 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
 532     _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
 533   assert(n_workers > 0, "Need at least one worker.");
 534   _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
 535   memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);
 536 }
 537 
 538 HeapRegionClaimer::~HeapRegionClaimer() {
 539   if (_claims != NULL) {
 540     FREE_C_HEAP_ARRAY(uint, _claims);
 541   }
 542 }
 543 
 544 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
 545   assert(worker_id < _n_workers, "Invalid worker_id.");
 546   return _n_regions * worker_id / _n_workers;
 547 }
 548 
 549 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
 550   assert(region_index < _n_regions, "Invalid index.");
 551   return _claims[region_index] == Claimed;
 552 }
 553 
 554 bool HeapRegionClaimer::claim_region(uint region_index) {
 555   assert(region_index < _n_regions, "Invalid index.");
 556   uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
 557   return old_val == Unclaimed;
 558 }