g1Allocator.cpp revision 8413:92457dfb91bd 
1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25#include "precompiled.hpp"
26#include "gc/g1/g1Allocator.hpp"
27#include "gc/g1/g1CollectedHeap.inline.hpp"
28#include "gc/g1/g1CollectorPolicy.hpp"
29#include "gc/g1/heapRegion.inline.hpp"
30#include "gc/g1/heapRegionSet.inline.hpp"
31
32void G1DefaultAllocator::init_mutator_alloc_region() {
33  assert(_mutator_alloc_region.get() == NULL, "pre-condition");
34  _mutator_alloc_region.init();
35}
36
37void G1DefaultAllocator::release_mutator_alloc_region() {
38  _mutator_alloc_region.release();
39  assert(_mutator_alloc_region.get() == NULL, "post-condition");
40}
41
42void G1Allocator::reuse_retained_old_region(EvacuationInfo& evacuation_info,
43                                            OldGCAllocRegion* old,
44                                            HeapRegion** retained_old) {
45  HeapRegion* retained_region = *retained_old;
46  *retained_old = NULL;
47
48  // We will discard the current GC alloc region if:
49  // a) it's in the collection set (it can happen!),
50  // b) it's already full (no point in using it),
51  // c) it's empty (this means that it was emptied during
52  // a cleanup and it should be on the free list now), or
53  // d) it's humongous (this means that it was emptied
54  // during a cleanup and was added to the free list, but
55  // has been subsequently used to allocate a humongous
56  // object that may be less than the region size).
57  if (retained_region != NULL &&
58      !retained_region->in_collection_set() &&
59      !(retained_region->top() == retained_region->end()) &&
60      !retained_region->is_empty() &&
61      !retained_region->is_humongous()) {
62    retained_region->record_timestamp();
63    // The retained region was added to the old region set when it was
64    // retired. We have to remove it now, since we don't allow regions
65    // we allocate to in the region sets. We'll re-add it later, when
66    // it's retired again.
67    _g1h->_old_set.remove(retained_region);
68    bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
69    retained_region->note_start_of_copying(during_im);
70    old->set(retained_region);
71    _g1h->_hr_printer.reuse(retained_region);
72    evacuation_info.set_alloc_regions_used_before(retained_region->used());
73  }
74}
75
76void G1DefaultAllocator::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
77  assert_at_safepoint(true /* should_be_vm_thread */);
78
79  _survivor_gc_alloc_region.init();
80  _old_gc_alloc_region.init();
81  reuse_retained_old_region(evacuation_info,
82                            &_old_gc_alloc_region,
83                            &_retained_old_gc_alloc_region);
84}
85
86void G1DefaultAllocator::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
87  AllocationContext_t context = AllocationContext::current();
88  evacuation_info.set_allocation_regions(survivor_gc_alloc_region(context)->count() +
89                                         old_gc_alloc_region(context)->count());
90  survivor_gc_alloc_region(context)->release();
91  // If we have an old GC alloc region to release, we'll save it in
92  // _retained_old_gc_alloc_region. If we don't
93  // _retained_old_gc_alloc_region will become NULL. This is what we
94  // want either way so no reason to check explicitly for either
95  // condition.
96  _retained_old_gc_alloc_region = old_gc_alloc_region(context)->release();
97  if (_retained_old_gc_alloc_region != NULL) {
98    _retained_old_gc_alloc_region->record_retained_region();
99  }
100
101  if (ResizePLAB) {
102    _g1h->alloc_buffer_stats(InCSetState::Young)->adjust_desired_plab_sz(no_of_gc_workers);
103    _g1h->alloc_buffer_stats(InCSetState::Old)->adjust_desired_plab_sz(no_of_gc_workers);
104  }
105}
106
107void G1DefaultAllocator::abandon_gc_alloc_regions() {
108  assert(survivor_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
109  assert(old_gc_alloc_region(AllocationContext::current())->get() == NULL, "pre-condition");
110  _retained_old_gc_alloc_region = NULL;
111}
112
113G1PLAB::G1PLAB(size_t gclab_word_size) :
114  PLAB(gclab_word_size), _retired(true) { }
115
116HeapWord* G1ParGCAllocator::allocate_direct_or_new_plab(InCSetState dest,
117                                                        size_t word_sz,
118                                                        AllocationContext_t context) {
119  size_t gclab_word_size = _g1h->desired_plab_sz(dest);
120  if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {
121    G1PLAB* alloc_buf = alloc_buffer(dest, context);
122    alloc_buf->retire();
123
124    HeapWord* buf = _g1h->par_allocate_during_gc(dest, gclab_word_size, context);
125    if (buf == NULL) {
126      return NULL; // Let caller handle allocation failure.
127    }
128    // Otherwise.
129    alloc_buf->set_word_size(gclab_word_size);
130    alloc_buf->set_buf(buf);
131
132    HeapWord* const obj = alloc_buf->allocate(word_sz);
133    assert(obj != NULL, "buffer was definitely big enough...");
134    return obj;
135  } else {
136    return _g1h->par_allocate_during_gc(dest, word_sz, context);
137  }
138}
139
140G1DefaultParGCAllocator::G1DefaultParGCAllocator(G1CollectedHeap* g1h) :
141  G1ParGCAllocator(g1h),
142  _surviving_alloc_buffer(g1h->desired_plab_sz(InCSetState::Young)),
143  _tenured_alloc_buffer(g1h->desired_plab_sz(InCSetState::Old)) {
144  for (uint state = 0; state < InCSetState::Num; state++) {
145    _alloc_buffers[state] = NULL;
146  }
147  _alloc_buffers[InCSetState::Young] = &_surviving_alloc_buffer;
148  _alloc_buffers[InCSetState::Old]  = &_tenured_alloc_buffer;
149}
150
151void G1DefaultParGCAllocator::retire_alloc_buffers() {
152  for (uint state = 0; state < InCSetState::Num; state++) {
153    G1PLAB* const buf = _alloc_buffers[state];
154    if (buf != NULL) {
155      buf->flush_and_retire_stats(_g1h->alloc_buffer_stats(state));
156    }
157  }
158}
159
160void G1DefaultParGCAllocator::waste(size_t& wasted, size_t& undo_wasted) {
161  wasted = 0;
162  undo_wasted = 0;
163  for (uint state = 0; state < InCSetState::Num; state++) {
164    G1PLAB * const buf = _alloc_buffers[state];
165    if (buf != NULL) {
166      wasted += buf->waste();
167      undo_wasted += buf->undo_waste();
168    }
169  }
170}
171