1 /*
2 * Copyright (c) 2014, 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.
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP
27
28 #include "gc_implementation/g1/g1AllocationContext.hpp"
29 #include "gc_implementation/g1/g1AllocRegion.hpp"
30 #include "gc_implementation/g1/g1InCSetState.hpp"
31 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
32
33 // Interface to keep track of which regions G1 is currently allocating into and
34 // allowing access to it (e.g. allocating into them, or getting their occupancy).
35 // Also keeps track of retained regions across GCs.
36 class G1Allocator : public CHeapObj<mtGC> {
37 friend class VMStructs;
38 protected:
39 G1CollectedHeap* _g1h;
40
41 public:
42 G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { }
43
44 static G1Allocator* create_allocator(G1CollectedHeap* g1h);
45
46 virtual void init_mutator_alloc_region() = 0;
47 virtual void release_mutator_alloc_region() = 0;
48
49 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
50 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) = 0;
51 virtual void abandon_gc_alloc_regions() = 0;
52
53 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0;
54 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
55 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0;
56
57 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
58 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
59 OldGCAllocRegion* old,
60 HeapRegion** retained);
61
62 // Returns the amount of memory that is in use by the managed allocation regions.
63 virtual size_t used_in_alloc_regions() const = 0;
64 };
65
66 // The default allocation region manager for G1. Provides a single mutator, survivor
67 // and old generation allocation region.
68 // Can retain the old generation allocation region across GCs.
69 class G1DefaultAllocator : public G1Allocator {
70 protected:
71 // Alloc region used to satisfy mutator allocation requests.
72 MutatorAllocRegion _mutator_alloc_region;
73
74 // Alloc region used to satisfy allocation requests by the GC for
75 // survivor objects.
76 SurvivorGCAllocRegion _survivor_gc_alloc_region;
77
78 // Alloc region used to satisfy allocation requests by the GC for
79 // old objects.
80 OldGCAllocRegion _old_gc_alloc_region;
81
82 HeapRegion* _retained_old_gc_alloc_region;
83 public:
84 G1DefaultAllocator(G1CollectedHeap* heap) : G1Allocator(heap), _retained_old_gc_alloc_region(NULL) { }
85
86 virtual void init_mutator_alloc_region();
87 virtual void release_mutator_alloc_region();
88
89 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
90 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
91 virtual void abandon_gc_alloc_regions();
92
93 virtual bool is_retained_old_region(HeapRegion* hr) {
94 return _retained_old_gc_alloc_region == hr;
95 }
96
97 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
98 return &_mutator_alloc_region;
99 }
100
101 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
102 return &_survivor_gc_alloc_region;
103 }
104
105 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
106 return &_old_gc_alloc_region;
107 }
108
109 virtual size_t used_in_alloc_regions() const {
110 assert(Heap_lock->owner() != NULL,
111 "Should be owned on this thread's behalf.");
112 size_t result = 0;
113
114 // Read only once in case it is set to NULL concurrently
115 HeapRegion* hr = _mutator_alloc_region.get();
116 if (hr != NULL) {
117 result += hr->used();
118 }
119 return result;
120 }
121 };
122
123 // A PLAB used during garbage collection that is specific to G1.
124 class G1PLAB: public ParGCAllocBuffer {
125 private:
126 bool _retired;
127
128 public:
129 G1PLAB(size_t gclab_word_size);
130 virtual ~G1PLAB() {
131 guarantee(_retired, "Allocation buffer has not been retired");
132 }
133
134 virtual void set_buf(HeapWord* buf) {
135 ParGCAllocBuffer::set_buf(buf);
136 _retired = false;
137 }
138
139 virtual void retire() {
140 if (_retired) {
141 return;
142 }
143 ParGCAllocBuffer::retire();
144 _retired = true;
145 }
146 };
147
148 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
149 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
150 // statistics.
151 class G1PLABAllocator : public CHeapObj<mtGC> {
152 friend class G1ParScanThreadState;
153 protected:
154 G1CollectedHeap* _g1h;
155
156 // The survivor alignment in effect in bytes.
157 // == 0 : don't align survivors
158 // != 0 : align survivors to that alignment
159 // These values were chosen to favor the non-alignment case since some
160 // architectures have a special compare against zero instructions.
161 const uint _survivor_alignment_bytes;
162
163 size_t _alloc_buffer_waste;
164 size_t _undo_waste;
165
166 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; }
167 void add_to_undo_waste(size_t waste) { _undo_waste += waste; }
168
169 virtual void retire_alloc_buffers() = 0;
170 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
171
172 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
173 // there are no restrictions on survivor alignment.
174 static uint calc_survivor_alignment_bytes() {
175 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
176 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
177 // No need to align objects in the survivors differently, return 0
178 // which means "survivor alignment is not used".
179 return 0;
180 } else {
181 assert(SurvivorAlignmentInBytes > 0, "sanity");
182 return SurvivorAlignmentInBytes;
183 }
184 }
185
186 public:
187 G1PLABAllocator(G1CollectedHeap* g1h) :
188 _g1h(g1h), _survivor_alignment_bytes(calc_survivor_alignment_bytes()),
189 _alloc_buffer_waste(0), _undo_waste(0) {
190 }
191
192 static G1PLABAllocator* create_allocator(G1CollectedHeap* g1h);
193
194 size_t alloc_buffer_waste() { return _alloc_buffer_waste; }
195 size_t undo_waste() {return _undo_waste; }
196
197 // Allocate word_sz words in dest, either directly into the regions or by
198 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
199 // not successful.
200 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
201 size_t word_sz,
202 AllocationContext_t context);
203
204 // Allocate word_sz words in the PLAB of dest. Returns the address of the
205 // allocated memory, NULL if not successful.
206 HeapWord* plab_allocate(InCSetState dest,
207 size_t word_sz,
208 AllocationContext_t context) {
209 G1PLAB* buffer = alloc_buffer(dest, context);
210 if (_survivor_alignment_bytes == 0) {
211 return buffer->allocate(word_sz);
212 } else {
213 return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes);
214 }
215 }
216
217 HeapWord* allocate(InCSetState dest, size_t word_sz,
218 AllocationContext_t context) {
219 HeapWord* const obj = plab_allocate(dest, word_sz, context);
220 if (obj != NULL) {
221 return obj;
222 }
223 return allocate_direct_or_new_plab(dest, word_sz, context);
224 }
225
226 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) {
227 if (alloc_buffer(dest, context)->contains(obj)) {
228 assert(alloc_buffer(dest, context)->contains(obj + word_sz - 1),
229 "should contain whole object");
230 alloc_buffer(dest, context)->undo_allocation(obj, word_sz);
231 } else {
232 CollectedHeap::fill_with_object(obj, word_sz);
233 add_to_undo_waste(word_sz);
234 }
235 }
236 };
237
238 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
239 // and old generation allocation.
240 class G1DefaultPLABAllocator : public G1PLABAllocator {
241 G1PLAB _surviving_alloc_buffer;
242 G1PLAB _tenured_alloc_buffer;
243 G1PLAB* _alloc_buffers[InCSetState::Num];
244
245 public:
246 G1DefaultPLABAllocator(G1CollectedHeap* g1h);
247
248 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
249 assert(dest.is_valid(),
250 err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()));
251 assert(_alloc_buffers[dest.value()] != NULL,
252 err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()));
253 return _alloc_buffers[dest.value()];
254 }
255
256 virtual void retire_alloc_buffers() ;
257 };
258
259 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP