1 /*

     2  * Copyright (c) 2014, 2017, 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/g1Allocator.inline.hpp"

    27 #include "gc/g1/g1AllocRegion.inline.hpp"

    28 #include "gc/g1/g1EvacStats.inline.hpp"

    29 #include "gc/g1/g1CollectedHeap.inline.hpp"

    30 #include "gc/g1/heapRegion.inline.hpp"

    31 #include "gc/g1/heapRegionSet.inline.hpp"

    32 #include "utilities/align.hpp"

    33 

    34 G1DefaultAllocator::G1DefaultAllocator(G1CollectedHeap* heap) :

    35   G1Allocator(heap),

    36   _survivor_is_full(false),

    37   _old_is_full(false),

    38   _retained_old_gc_alloc_region(NULL),

    39   _survivor_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Young)),

    40   _old_gc_alloc_region(heap->alloc_buffer_stats(InCSetState::Old)) {

    41 }

    42 

    43 void G1DefaultAllocator::init_mutator_alloc_region() {

    44   assert(_mutator_alloc_region.get() == NULL, "pre-condition");

    45   _mutator_alloc_region.init();

    46 }

    47 

    48 void G1DefaultAllocator::release_mutator_alloc_region() {

    49   _mutator_alloc_region.release();

    50   assert(_mutator_alloc_region.get() == NULL, "post-condition");

    51 }

    52 

    53 void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,

    54                                             OldGCAllocRegion* old,

    55                                             HeapRegion** retained_old) {

    56   HeapRegion* retained_region = *retained_old;

    57   *retained_old = NULL;

    58   assert(retained_region == NULL || !retained_region->is_archive(),

    59          "Archive region should not be alloc region (index %u)", retained_region->hrm_index());

    60 

    61   // We will discard the current GC alloc region if:

    62   // a) it's in the collection set (it can happen!),

    63   // b) it's already full (no point in using it),

    64   // c) it's empty (this means that it was emptied during

    65   // a cleanup and it should be on the free list now), or

    66   // d) it's humongous (this means that it was emptied

    67   // during a cleanup and was added to the free list, but

    68   // has been subsequently used to allocate a humongous

    69   // object that may be less than the region size).

    70   if (retained_region != NULL &&

    71       !retained_region->in_collection_set() &&

    72       !(retained_region->top() == retained_region->end()) &&

    73       !retained_region->is_empty() &&

    74       !retained_region->is_humongous()) {

    75     retained_region->record_timestamp();

    76     // The retained region was added to the old region set when it was

    77     // retired. We have to remove it now, since we don't allow regions

    78     // we allocate to in the region sets. We'll re-add it later, when

    79     // it's retired again.

    80     _g1h->old_set_remove(retained_region);

    81     bool during_im = _g1h->collector_state()->during_initial_mark_pause();

    82     retained_region->note_start_of_copying(during_im);

    83     old->set(retained_region);

    84     _g1h->hr_printer()->reuse(retained_region);

    85     evacuation_info.set_alloc_regions_used_before(retained_region->used());

    86   }

    87 }

    88 

    89 void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {

    90   assert_at_safepoint(true /* should_be_vm_thread */);

    91 

    92   _survivor_is_full = false;

    93   _old_is_full = false;

    94 

    95   _survivor_gc_alloc_region.init();

    96   _old_gc_alloc_region.init();

    97   reuse_retained_old_region(evacuation_info,

    98                             &_old_gc_alloc_region,

    99                             &_retained_old_gc_alloc_region);

   100 }

   101 

   102 void G1DefaultAllocator::release_gc_alloc_regions(EvacuationInfo& evacuation_info) {

   103   AllocationContext_t context = AllocationContext::current();

   104   evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +

   105                                          old_gc_alloc_region(context)->count());

   106   survivor_gc_alloc_region(context)->release();

   107   // If we have an old GC alloc region to release, we'll save it in

   108   // _retained_old_gc_alloc_region. If we don't

   109   // _retained_old_gc_alloc_region will become NULL. This is what we

   110   // want either way so no reason to check explicitly for either

   111   // condition.

   112   _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();

   113 }

   114 

   115 void G1DefaultAllocator::abandon_gc_alloc_regions() {

   116   assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");

   117   assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");

   118   _retained_old_gc_alloc_region = NULL;

   119 }

   120 

   121 bool G1DefaultAllocator::survivor_is_full(AllocationContext_t context) const {

   122   return _survivor_is_full;

   123 }

   124 

   125 bool G1DefaultAllocator::old_is_full(AllocationContext_t context) const {

   126   return _old_is_full;

   127 }

   128 

   129 void G1DefaultAllocator::set_survivor_full(AllocationContext_t context) {

   130   _survivor_is_full = true;

   131 }

   132 

   133 void G1DefaultAllocator::set_old_full(AllocationContext_t context) {

   134   _old_is_full = true;

   135 }

   136 

   137 G1PLAB::G1PLAB(size_t gclab_word_size) :

   138   PLAB(gclab_word_size), _retired(true) { }

   139 

   140 size_t G1Allocator::unsafe_max_tlab_alloc(AllocationContext_t context) {

   141   // Return the remaining space in the cur alloc region, but not less than

   142   // the min TLAB size.

   143 

   144   // Also, this value can be at most the humongous object threshold,

   145   // since we can't allow tlabs to grow big enough to accommodate

   146   // humongous objects.

   147 

   148   HeapRegion* hr = mutator_alloc_region(context)->get();

   149   size_t max_tlab = _g1h->max_tlab_size() * wordSize;

   150   if (hr == NULL) {

   151     return max_tlab;

   152   } else {

   153     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);

   154   }

   155 }

   156 

   157 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,

   158                                               size_t word_size,

   159                                               AllocationContext_t context) {

   160   size_t temp = 0;

   161   HeapWord* result = par_allocate_during_gc(dest, word_size, word_size, &temp, context);

   162   assert(result == NULL || temp == word_size,

   163          "Requested " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,

   164          word_size, temp, p2i(result));

   165   return result;

   166 }

   167 

   168 HeapWord* G1Allocator::par_allocate_during_gc(InCSetState dest,

   169                                               size_t min_word_size,

   170                                               size_t desired_word_size,

   171                                               size_t* actual_word_size,

   172                                               AllocationContext_t context) {

   173   switch (dest.value()) {

   174     case InCSetState::Young:

   175       return survivor_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);

   176     case InCSetState::Old:

   177       return old_attempt_allocation(min_word_size, desired_word_size, actual_word_size, context);

   178     default:

   179       ShouldNotReachHere();

   180       return NULL; // Keep some compilers happy

   181   }

   182 }

   183 

   184 HeapWord* G1Allocator::survivor_attempt_allocation(size_t min_word_size,

   185                                                    size_t desired_word_size,

   186                                                    size_t* actual_word_size,

   187                                                    AllocationContext_t context) {

   188   assert(!_g1h->is_humongous(desired_word_size),

   189          "we should not be seeing humongous-size allocations in this path");

   190 

   191   HeapWord* result = survivor_gc_alloc_region(context)->attempt_allocation(min_word_size,

   192                                                                            desired_word_size,

   193                                                                            actual_word_size,

   194                                                                            false /* bot_updates */);

   195   if (result == NULL && !survivor_is_full(context)) {

   196     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);

   197     result = survivor_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,

   198                                                                           desired_word_size,

   199                                                                           actual_word_size,

   200                                                                           false /* bot_updates */);

   201     if (result == NULL) {

   202       set_survivor_full(context);

   203     }

   204   }

   205   if (result != NULL) {

   206     _g1h->dirty_young_block(result, *actual_word_size);

   207   }

   208   return result;

   209 }

   210 

   211 HeapWord* G1Allocator::old_attempt_allocation(size_t min_word_size,

   212                                               size_t desired_word_size,

   213                                               size_t* actual_word_size,

   214                                               AllocationContext_t context) {

   215   assert(!_g1h->is_humongous(desired_word_size),

   216          "we should not be seeing humongous-size allocations in this path");

   217 

   218   HeapWord* result = old_gc_alloc_region(context)->attempt_allocation(min_word_size,

   219                                                                       desired_word_size,

   220                                                                       actual_word_size,

   221                                                                       true /* bot_updates */);

   222   if (result == NULL && !old_is_full(context)) {

   223     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);

   224     result = old_gc_alloc_region(context)->attempt_allocation_locked(min_word_size,

   225                                                                      desired_word_size,

   226                                                                      actual_word_size,

   227                                                                      true /* bot_updates */);

   228     if (result == NULL) {

   229       set_old_full(context);

   230     }

   231   }

   232   return result;

   233 }

   234 

   235 G1PLABAllocator::G1PLABAllocator(G1Allocator* allocator) :

   236   _g1h(G1CollectedHeap::heap()),

   237   _allocator(allocator),

   238   _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {

   239   for (size_t i = 0; i < ARRAY_SIZE(_direct_allocated); i++) {

   240     _direct_allocated[i] = 0;

   241   }

   242 }

   243 

   244 bool G1PLABAllocator::may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const {

   245   return (allocation_word_sz * 100 < buffer_size * ParallelGCBufferWastePct);

   246 }

   247 

   248 HeapWord* G1PLABAllocator::allocate_direct_or_new_plab(InCSetState dest,

   249                                                        size_t word_sz,

   250                                                        AllocationContext_t context,

   251                                                        bool* plab_refill_failed) {

   252   size_t plab_word_size = G1CollectedHeap::heap()->desired_plab_sz(dest);

   253   size_t required_in_plab = PLAB::size_required_for_allocation(word_sz);

   254 

   255   // Only get a new PLAB if the allocation fits and it would not waste more than

   256   // ParallelGCBufferWastePct in the existing buffer.

   257   if ((required_in_plab <= plab_word_size) &&

   258     may_throw_away_buffer(required_in_plab, plab_word_size)) {

   259 

   260     G1PLAB* alloc_buf = alloc_buffer(dest, context);

   261     alloc_buf->retire();

   262 

   263     size_t actual_plab_size = 0;

   264     HeapWord* buf = _allocator->par_allocate_during_gc(dest,

   265                                                        required_in_plab,

   266                                                        plab_word_size,

   267                                                        &actual_plab_size,

   268                                                        context);

   269 

   270     assert(buf == NULL || ((actual_plab_size >= required_in_plab) && (actual_plab_size <= plab_word_size)),

   271            "Requested at minimum " SIZE_FORMAT ", desired " SIZE_FORMAT " words, but got " SIZE_FORMAT " at " PTR_FORMAT,

   272            required_in_plab, plab_word_size, actual_plab_size, p2i(buf));

   273 

   274     if (buf != NULL) {

   275       alloc_buf->set_buf(buf, actual_plab_size);

   276 

   277       HeapWord* const obj = alloc_buf->allocate(word_sz);

   278       assert(obj != NULL, "PLAB should have been big enough, tried to allocate "

   279                           SIZE_FORMAT " requiring " SIZE_FORMAT " PLAB size " SIZE_FORMAT,

   280                           word_sz, required_in_plab, plab_word_size);

   281       return obj;

   282     }

   283     // Otherwise.

   284     *plab_refill_failed = true;

   285   }

   286   // Try direct allocation.

   287   HeapWord* result = _allocator->par_allocate_during_gc(dest, word_sz, context);

   288   if (result != NULL) {

   289     _direct_allocated[dest.value()] += word_sz;

   290   }

   291   return result;

   292 }

   293 

   294 void G1PLABAllocator::undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {

   295   alloc_buffer(dest, context)->undo_allocation(obj, word_sz);

   296 }

   297 

   298 G1DefaultPLABAllocator::G1DefaultPLABAllocator(G1Allocator* allocator) :

   299   G1PLABAllocator(allocator),

   300   _surviving_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Young)),

   301   _tenured_alloc_buffer(_g1h->desired_plab_sz(InCSetState::Old)) {

   302   for (uint state = 0; state < InCSetState::Num; state++) {

   303     _alloc_buffers[state] = NULL;

   304   }

   305   _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;

   306   _alloc_buffers[InCSetState::Old]  = &_tenured_alloc_buffer;

   307 }

   308 

   309 void G1DefaultPLABAllocator::flush_and_retire_stats() {

   310   for (uint state = 0; state < InCSetState::Num; state++) {

   311     G1PLAB* const buf = _alloc_buffers[state];

   312     if (buf != NULL) {

   313       G1EvacStats* stats = _g1h->alloc_buffer_stats(state);

   314       buf->flush_and_retire_stats(stats);

   315       stats->add_direct_allocated(_direct_allocated[state]);

   316       _direct_allocated[state] = 0;

   317     }

   318   }

   319 }

   320 

   321 void G1DefaultPLABAllocator::waste(size_t& wasted, size_t& undo_wasted) {

   322   wasted = 0;

   323   undo_wasted = 0;

   324   for (uint state = 0; state < InCSetState::Num; state++) {

   325     G1PLAB * const buf = _alloc_buffers[state];

   326     if (buf != NULL) {

   327       wasted += buf->waste();

   328       undo_wasted += buf->undo_waste();

   329     }

   330   }

   331 }

   332 

   333 bool G1ArchiveAllocator::_archive_check_enabled = false;

   334 G1ArchiveRegionMap G1ArchiveAllocator::_closed_archive_region_map;

   335 G1ArchiveRegionMap G1ArchiveAllocator::_open_archive_region_map;

   336 

   337 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {

   338   // Create the archive allocator, and also enable archive object checking

   339   // in mark-sweep, since we will be creating archive regions.

   340   G1ArchiveAllocator* result =  new G1ArchiveAllocator(g1h, open);

   341   enable_archive_object_check();

   342   return result;

   343 }

   344 

   345 bool G1ArchiveAllocator::alloc_new_region() {

   346   // Allocate the highest free region in the reserved heap,

   347   // and add it to our list of allocated regions. It is marked

   348   // archive and added to the old set.

   349   HeapRegion* hr = _g1h->alloc_highest_free_region();

   350   if (hr == NULL) {

   351     return false;

   352   }

   353   assert(hr->is_empty(), "expected empty region (index %u)", hr->hrm_index());

   354   if (_open) {

   355     hr->set_open_archive();

   356   } else {

   357     hr->set_closed_archive();

   358   }

   359   _g1h->old_set_add(hr);

   360   _g1h->hr_printer()->alloc(hr);

   361   _allocated_regions.append(hr);

   362   _allocation_region = hr;

   363 

   364   // Set up _bottom and _max to begin allocating in the lowest

   365   // min_region_size'd chunk of the allocated G1 region.

   366   _bottom = hr->bottom();

   367   _max = _bottom + HeapRegion::min_region_size_in_words();

   368 

   369   // Tell mark-sweep that objects in this region are not to be marked.

   370   set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);

   371 

   372   // Since we've modified the old set, call update_sizes.

   373   _g1h->g1mm()->update_sizes();

   374   return true;

   375 }

   376 

   377 HeapWord* G1ArchiveAllocator::archive_mem_allocate(size_t word_size) {

   378   assert(word_size != 0, "size must not be zero");

   379   if (_allocation_region == NULL) {

   380     if (!alloc_new_region()) {

   381       return NULL;

   382     }

   383   }

   384   HeapWord* old_top = _allocation_region->top();

   385   assert(_bottom >= _allocation_region->bottom(),

   386          "inconsistent allocation state: " PTR_FORMAT " < " PTR_FORMAT,

   387          p2i(_bottom), p2i(_allocation_region->bottom()));

   388   assert(_max <= _allocation_region->end(),

   389          "inconsistent allocation state: " PTR_FORMAT " > " PTR_FORMAT,

   390          p2i(_max), p2i(_allocation_region->end()));

   391   assert(_bottom <= old_top && old_top <= _max,

   392          "inconsistent allocation state: expected "

   393          PTR_FORMAT " <= " PTR_FORMAT " <= " PTR_FORMAT,

   394          p2i(_bottom), p2i(old_top), p2i(_max));

   395 

   396   // Allocate the next word_size words in the current allocation chunk.

   397   // If allocation would cross the _max boundary, insert a filler and begin

   398   // at the base of the next min_region_size'd chunk. Also advance to the next

   399   // chunk if we don't yet cross the boundary, but the remainder would be too

   400   // small to fill.

   401   HeapWord* new_top = old_top + word_size;

   402   size_t remainder = pointer_delta(_max, new_top);

   403   if ((new_top > _max) ||

   404       ((new_top < _max) && (remainder < CollectedHeap::min_fill_size()))) {

   405     if (old_top != _max) {

   406       size_t fill_size = pointer_delta(_max, old_top);

   407       CollectedHeap::fill_with_object(old_top, fill_size);

   408       _summary_bytes_used += fill_size * HeapWordSize;

   409     }

   410     _allocation_region->set_top(_max);

   411     old_top = _bottom = _max;

   412 

   413     // Check if we've just used up the last min_region_size'd chunk

   414     // in the current region, and if so, allocate a new one.

   415     if (_bottom != _allocation_region->end()) {

   416       _max = _bottom + HeapRegion::min_region_size_in_words();

   417     } else {

   418       if (!alloc_new_region()) {

   419         return NULL;

   420       }

   421       old_top = _allocation_region->bottom();

   422     }

   423   }

   424   _allocation_region->set_top(old_top + word_size);

   425   _summary_bytes_used += word_size * HeapWordSize;

   426 

   427   return old_top;

   428 }

   429 

   430 void G1ArchiveAllocator::complete_archive(GrowableArray<MemRegion>* ranges,

   431                                           size_t end_alignment_in_bytes) {

   432   assert((end_alignment_in_bytes >> LogHeapWordSize) < HeapRegion::min_region_size_in_words(),

   433          "alignment " SIZE_FORMAT " too large", end_alignment_in_bytes);

   434   assert(is_aligned(end_alignment_in_bytes, HeapWordSize),

   435          "alignment " SIZE_FORMAT " is not HeapWord (%u) aligned", end_alignment_in_bytes, HeapWordSize);

   436 

   437   // If we've allocated nothing, simply return.

   438   if (_allocation_region == NULL) {

   439     return;

   440   }

   441 

   442   // If an end alignment was requested, insert filler objects.

   443   if (end_alignment_in_bytes != 0) {

   444     HeapWord* currtop = _allocation_region->top();

   445     HeapWord* newtop = align_up(currtop, end_alignment_in_bytes);

   446     size_t fill_size = pointer_delta(newtop, currtop);

   447     if (fill_size != 0) {

   448       if (fill_size < CollectedHeap::min_fill_size()) {

   449         // If the required fill is smaller than we can represent,

   450         // bump up to the next aligned address. We know we won't exceed the current

   451         // region boundary because the max supported alignment is smaller than the min

   452         // region size, and because the allocation code never leaves space smaller than

   453         // the min_fill_size at the top of the current allocation region.

   454         newtop = align_up(currtop + CollectedHeap::min_fill_size(),

   455                           end_alignment_in_bytes);

   456         fill_size = pointer_delta(newtop, currtop);

   457       }

   458       HeapWord* fill = archive_mem_allocate(fill_size);

   459       CollectedHeap::fill_with_objects(fill, fill_size);

   460     }

   461   }

   462 

   463   // Loop through the allocated regions, and create MemRegions summarizing

   464   // the allocated address range, combining contiguous ranges. Add the

   465   // MemRegions to the GrowableArray provided by the caller.

   466   int index = _allocated_regions.length() - 1;

   467   assert(_allocated_regions.at(index) == _allocation_region,

   468          "expected region %u at end of array, found %u",

   469          _allocation_region->hrm_index(), _allocated_regions.at(index)->hrm_index());

   470   HeapWord* base_address = _allocation_region->bottom();

   471   HeapWord* top = base_address;

   472 

   473   while (index >= 0) {

   474     HeapRegion* next = _allocated_regions.at(index);

   475     HeapWord* new_base = next->bottom();

   476     HeapWord* new_top = next->top();

   477     if (new_base != top) {

   478       ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));

   479       base_address = new_base;

   480     }

   481     top = new_top;

   482     index = index - 1;

   483   }

   484 

   485   assert(top != base_address, "zero-sized range, address " PTR_FORMAT, p2i(base_address));

   486   ranges->append(MemRegion(base_address, pointer_delta(top, base_address)));

   487   _allocated_regions.clear();

   488   _allocation_region = NULL;

   489 };