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->allocator()->new_heap_region(hrm_index, g1h->bot_shared(), 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 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {

   282   const uint start_index = hrclaimer->start_region_for_worker(worker_id);

   283 

   284   // Every worker will actually look at all regions, skipping over regions that

   285   // are currently not committed.

   286   // This also (potentially) iterates over regions newly allocated during GC. This

   287   // is no problem except for some extra work.

   288   const uint n_regions = hrclaimer->n_regions();

   289   for (uint count = 0; count < n_regions; count++) {

   290     const uint index = (start_index + count) % n_regions;

   291     assert(index < n_regions, "sanity");

   292     // Skip over unavailable regions

   293     if (!is_available(index)) {

   294       continue;

   295     }

   296     HeapRegion* r = _regions.get_by_index(index);

   297     // We'll ignore "continues humongous" regions (we'll process them

   298     // when we come across their corresponding "start humongous"

   299     // region) and regions already claimed.

   300     // However, if the iteration is specified as concurrent, the values for

   301     // is_starts_humongous and is_continues_humongous can not be trusted,

   302     // and we should just blindly iterate over regions regardless of their

   303     // humongous status.

   304     if (hrclaimer->is_region_claimed(index) || (!concurrent && r->is_continues_humongous())) {

   305       continue;

   306     }

   307     // OK, try to claim it

   308     if (!hrclaimer->claim_region(index)) {

   309       continue;

   310     }

   311     // Success!

   312     // As mentioned above, special treatment of humongous regions can only be

   313     // done if we are iterating non-concurrently.

   314     if (!concurrent && r->is_starts_humongous()) {

   315       // If the region is "starts humongous" we'll iterate over its

   316       // "continues humongous" first; in fact we'll do them

   317       // first. The order is important. In one case, calling the

   318       // closure on the "starts humongous" region might de-allocate

   319       // and clear all its "continues humongous" regions and, as a

   320       // result, we might end up processing them twice. So, we'll do

   321       // them first (note: most closures will ignore them anyway) and

   322       // then we'll do the "starts humongous" region.

   323       for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {

   324         HeapRegion* chr = _regions.get_by_index(ch_index);

   325 

   326         assert(chr->is_continues_humongous(), "Must be humongous region");

   327         assert(chr->humongous_start_region() == r,

   328                err_msg("Must work on humongous continuation of the original start region "

   329                        PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));

   330         assert(!hrclaimer->is_region_claimed(ch_index),

   331                "Must not have been claimed yet because claiming of humongous continuation first claims the start region");

   332 

   333         // Claim the region so no other worker tries to process the region. When a worker processes a

   334         // starts_humongous region it may also process the associated continues_humongous regions.

   335         // The continues_humongous regions can be changed to free regions. Unless this worker claims

   336         // all of these regions, other workers might try claim and process these newly free regions.

   337         bool claim_result = hrclaimer->claim_region(ch_index);

   338         guarantee(claim_result, "We should always be able to claim the continuesHumongous part of the humongous object");

   339 

   340         bool res2 = blk->doHeapRegion(chr);

   341         if (res2) {

   342           return;

   343         }

   344 

   345         // Right now, this holds (i.e., no closure that actually

   346         // does something with "continues humongous" regions

   347         // clears them). We might have to weaken it in the future,

   348         // but let's leave these two asserts here for extra safety.

   349         assert(chr->is_continues_humongous(), "should still be the case");

   350         assert(chr->humongous_start_region() == r, "sanity");

   351       }

   352     }

   353 

   354     bool res = blk->doHeapRegion(r);

   355     if (res) {

   356       return;

   357     }

   358   }

   359 }

   360 

   361 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {

   362   assert(length() > 0, "the region sequence should not be empty");

   363   assert(length() <= _allocated_heapregions_length, "invariant");

   364   assert(_allocated_heapregions_length > 0, "we should have at least one region committed");

   365   assert(num_regions_to_remove < length(), "We should never remove all regions");

   366 

   367   if (num_regions_to_remove == 0) {

   368     return 0;

   369   }

   370 

   371   uint removed = 0;

   372   uint cur = _allocated_heapregions_length - 1;

   373   uint idx_last_found = 0;

   374   uint num_last_found = 0;

   375 

   376   while ((removed < num_regions_to_remove) &&

   377       (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {

   378     uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);

   379 

   380     uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);

   381 

   382     cur -= num_last_found;

   383     removed += to_remove;

   384   }

   385 

   386   verify_optional();

   387 

   388   return removed;

   389 }

   390 

   391 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {

   392   guarantee(start_idx < _allocated_heapregions_length, "checking");

   393   guarantee(res_idx != NULL, "checking");

   394 

   395   uint num_regions_found = 0;

   396 

   397   jlong cur = start_idx;

   398   while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {

   399     cur--;

   400   }

   401   if (cur == -1) {

   402     return num_regions_found;

   403   }

   404   jlong old_cur = cur;

   405   // cur indexes the first empty region

   406   while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {

   407     cur--;

   408   }

   409   *res_idx = cur + 1;

   410   num_regions_found = old_cur - cur;

   411 

   412 #ifdef ASSERT

   413   for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {

   414     assert(at(i)->is_empty(), "just checking");

   415   }

   416 #endif

   417   return num_regions_found;

   418 }

   419 

   420 void HeapRegionManager::verify() {

   421   guarantee(length() <= _allocated_heapregions_length,

   422             err_msg("invariant: _length: %u _allocated_length: %u",

   423                     length(), _allocated_heapregions_length));

   424   guarantee(_allocated_heapregions_length <= max_length(),

   425             err_msg("invariant: _allocated_length: %u _max_length: %u",

   426                     _allocated_heapregions_length, max_length()));

   427 

   428   bool prev_committed = true;

   429   uint num_committed = 0;

   430   HeapWord* prev_end = heap_bottom();

   431   for (uint i = 0; i < _allocated_heapregions_length; i++) {

   432     if (!is_available(i)) {

   433       prev_committed = false;

   434       continue;

   435     }

   436     num_committed++;

   437     HeapRegion* hr = _regions.get_by_index(i);

   438     guarantee(hr != NULL, err_msg("invariant: i: %u", i));

   439     guarantee(!prev_committed || hr->bottom() == prev_end,

   440               err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,

   441                       i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));

   442     guarantee(hr->hrm_index() == i,

   443               err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));

   444     // Asserts will fire if i is >= _length

   445     HeapWord* addr = hr->bottom();

   446     guarantee(addr_to_region(addr) == hr, "sanity");

   447     // We cannot check whether the region is part of a particular set: at the time

   448     // this method may be called, we have only completed allocation of the regions,

   449     // but not put into a region set.

   450     prev_committed = true;

   451     if (hr->is_starts_humongous()) {

   452       prev_end = hr->orig_end();

   453     } else {

   454       prev_end = hr->end();

   455     }

   456   }

   457   for (uint i = _allocated_heapregions_length; i < max_length(); i++) {

   458     guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));

   459   }

   460 

   461   guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));

   462   _free_list.verify();

   463 }

   464 

   465 #ifndef PRODUCT

   466 void HeapRegionManager::verify_optional() {

   467   verify();

   468 }

   469 #endif // PRODUCT

   470 

   471 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :

   472     _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {

   473   assert(n_workers > 0, "Need at least one worker.");

   474   _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);

   475   memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);

   476 }

   477 

   478 HeapRegionClaimer::~HeapRegionClaimer() {

   479   if (_claims != NULL) {

   480     FREE_C_HEAP_ARRAY(uint, _claims);

   481   }

   482 }

   483 

   484 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {

   485   assert(worker_id < _n_workers, "Invalid worker_id.");

   486   return _n_regions * worker_id / _n_workers;

   487 }

   488 

   489 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {

   490   assert(region_index < _n_regions, "Invalid index.");

   491   return _claims[region_index] == Claimed;

   492 }

   493 

   494 bool HeapRegionClaimer::claim_region(uint region_index) {

   495   assert(region_index < _n_regions, "Invalid index.");

   496   uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);

   497   return old_val == Unclaimed;

   498 }