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 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0;
42 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
43 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0;
44
45 // Allocation attempt during GC for a survivor object / PLAB.
46 inline HeapWord* survivor_attempt_allocation(size_t min_word_size,
47 size_t& word_size,
48 AllocationContext_t context);
49
50 // Allocation attempt during GC for an old object / PLAB.
51 inline HeapWord* old_attempt_allocation(size_t min_word_size,
52 size_t& word_size,
53 AllocationContext_t context);
54
55 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
56 OldGCAllocRegion* old,
57 HeapRegion** retained);
58
59 public:
60 G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { }
61
62 static G1Allocator* create_allocator(G1CollectedHeap* g1h);
63
64 virtual void init_mutator_alloc_region() = 0;
65 virtual void release_mutator_alloc_region() = 0;
66
67 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
68 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) = 0;
69 virtual void abandon_gc_alloc_regions() = 0;
70
71 size_t desired_plab_size(InCSetState dest);
72 virtual G1EvacStats* evac_stats(InCSetState dest) = 0;
73
74 // Allocate blocks during garbage collection. Will ensure an allocation region
75 // is available, either by picking one or getting a new one from the heap,
76 // and then allocate a block of the given size. The block may not be a humongous -
77 // it must fit into a single heap region.
78 HeapWord* par_allocate_during_gc(InCSetState dest,
79 size_t min_word_size,
80 size_t& word_size,
81 AllocationContext_t context);
82
83 HeapWord* par_allocate_during_gc(InCSetState dest, size_t word_size, AllocationContext_t context) {
84 return par_allocate_during_gc(dest, word_size, word_size, context);
85 }
86
87 HeapWord* par_allocate_during_mutator(size_t word_size, bool bot_updates, AllocationContext_t context) {
88 return mutator_alloc_region(context)->attempt_allocation(word_size, bot_updates);
89 }
90
91 HeapWord* par_allocate_during_mutator_locked(size_t word_size, bool bot_updates, AllocationContext_t context) {
92 return mutator_alloc_region(context)->attempt_allocation_locked(word_size, bot_updates);
93 }
94
95 HeapWord* par_allocate_during_mutator_force(size_t word_size, bool bot_updates, AllocationContext_t context) {
96 return mutator_alloc_region(context)->attempt_allocation_force(word_size, bot_updates);
97 }
98
99 size_t unsafe_max_tlab_alloc();
100
101 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
102
103 // Returns the amount of memory that is in use by the managed allocation regions.
104 virtual size_t used_in_alloc_regions() const = 0;
105 };
106
107 // The default allocation region manager for G1. Provides a single mutator, survivor
108 // and old generation allocation region.
109 // Can retain the old generation allocation region across GCs.
110 class G1DefaultAllocator : public G1Allocator {
111 private:
112 // PLAB sizing policy for survivors.
113 G1EvacStats _survivor_plab_stats;
114 // PLAB sizing policy for tenured objects.
115 G1EvacStats _old_plab_stats;
116
117 protected:
118 // Alloc region used to satisfy mutator allocation requests.
119 MutatorAllocRegion _mutator_alloc_region;
120
121 // Alloc region used to satisfy allocation requests by the GC for
122 // survivor objects.
123 SurvivorGCAllocRegion _survivor_gc_alloc_region;
124
125 // Alloc region used to satisfy allocation requests by the GC for
126 // old objects.
127 OldGCAllocRegion _old_gc_alloc_region;
128
129 HeapRegion* _retained_old_gc_alloc_region;
130
131 G1EvacStats* evac_stats(InCSetState dest);
132
133 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
134 return &_mutator_alloc_region;
135 }
136
137 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
138 return &_survivor_gc_alloc_region;
139 }
140
141 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
142 return &_old_gc_alloc_region;
143 }
144
145 public:
146 G1DefaultAllocator(G1CollectedHeap* heap);
147
148 virtual void init_mutator_alloc_region();
149 virtual void release_mutator_alloc_region();
150
151 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
152 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info);
153 virtual void abandon_gc_alloc_regions();
154
155 virtual bool is_retained_old_region(HeapRegion* hr) {
156 return _retained_old_gc_alloc_region == hr;
157 }
158
159 virtual size_t used_in_alloc_regions() const {
160 assert(Heap_lock->owner() != NULL,
161 "Should be owned on this thread's behalf.");
162 size_t result = 0;
163
164 // Read only once in case it is set to NULL concurrently
165 HeapRegion* hr = _mutator_alloc_region.get();
166 if (hr != NULL) {
167 result += hr->used();
168 }
169 return result;
170 }
171 };
172
173 // A PLAB used during garbage collection that is specific to G1.
174 class G1PLAB: public ParGCAllocBuffer {
175 private:
176 bool _retired;
177
178 public:
179 G1PLAB(size_t gclab_word_size);
180 virtual ~G1PLAB() {
181 guarantee(_retired, "Allocation buffer has not been retired");
182 }
183
184 // The amount of space in words wasted within the PLAB including
185 // waste due to refills and alignment.
186 size_t wasted() const { return _wasted; }
187
188 virtual void set_buf(HeapWord* buf) {
189 ParGCAllocBuffer::set_buf(buf);
190 _retired = false;
191 }
192
193 virtual void retire() {
194 if (_retired) {
195 return;
196 }
197 ParGCAllocBuffer::retire();
198 _retired = true;
199 }
200 };
201
202 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
203 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
204 // statistics.
205 class PLABAllocator : public CHeapObj<mtGC> {
206 friend class G1ParScanThreadState;
207 protected:
208 G1Allocator* _allocator;
209
210 // The survivor alignment in effect in bytes.
211 // == 0 : don't align survivors
212 // != 0 : align survivors to that alignment
213 // These values were chosen to favor the non-alignment case since some
214 // architectures have a special compare against zero instructions.
215 const uint _survivor_alignment_bytes;
216
217 size_t _undo_waste[InCSetState::Num];
218 size_t _inline_allocated[InCSetState::Num];
219
220 virtual void flush_stats_and_retire() = 0;
221 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
222
223 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
224 // there are no restrictions on survivor alignment.
225 static uint calc_survivor_alignment_bytes() {
226 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
227 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
228 // No need to align objects in the survivors differently, return 0
229 // which means "survivor alignment is not used".
230 return 0;
231 } else {
232 assert(SurvivorAlignmentInBytes > 0, "sanity");
233 return SurvivorAlignmentInBytes;
234 }
235 }
236
237 public:
238 PLABAllocator(G1Allocator* heap_manager) :
239 _allocator(heap_manager), _survivor_alignment_bytes(calc_survivor_alignment_bytes()) {
240 for (size_t i = 0; i < ARRAY_SIZE(_inline_allocated); i++) {
241 _inline_allocated[i] = 0;
242 }
243 for (size_t i = 0; i < ARRAY_SIZE(_undo_waste); i++) {
244 _undo_waste[i] = 0;
245 }
246 }
247
248 static PLABAllocator* create_allocator(G1Allocator* allocator);
249
250 // Returns the number of words allocated inline for the given state so far.
251 size_t inline_allocated(InCSetState value) const { return _inline_allocated[value.value()]; }
252 // Returns the number of words wasted due to und for the given state so far.
253 size_t lab_undo_waste(InCSetState value) const { return _undo_waste[value.value()]; }
254 // Returns the number of words wasted due to alignment or LAB refills.
255 virtual size_t lab_waste(InCSetState value) const = 0;
256
257 // Allocate word_sz words in dest, either directly into the regions or by
258 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
259 // not successful.
260 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
261 size_t word_sz,
262 AllocationContext_t context);
263
264 // Allocate word_sz words in the PLAB of dest. Returns the address of the
265 // allocated memory, NULL if not successful.
266 HeapWord* plab_allocate(InCSetState dest,
267 size_t word_sz,
268 AllocationContext_t context) {
269 G1PLAB* buffer = alloc_buffer(dest, context);
270 if (_survivor_alignment_bytes == 0) {
271 return buffer->allocate(word_sz);
272 } else {
273 return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes);
274 }
275 }
276
277 HeapWord* allocate(InCSetState dest, size_t word_sz,
278 AllocationContext_t context) {
279 HeapWord* const obj = plab_allocate(dest, word_sz, context);
280 if (obj != NULL) {
281 return obj;
282 }
283 return allocate_direct_or_new_plab(dest, word_sz, context);
284 }
285
286 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
287 };
288
289 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
290 // and old generation allocation.
291 class DefaultPLABAllocator : public PLABAllocator {
292 G1PLAB _surviving_alloc_buffer;
293 G1PLAB _tenured_alloc_buffer;
294 G1PLAB* _alloc_buffers[InCSetState::Num];
295
296 public:
297 DefaultPLABAllocator(G1Allocator* allocator);
298
299 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
300 assert(dest.is_valid(),
301 err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()));
302 assert(_alloc_buffers[dest.value()] != NULL,
303 err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()));
304 return _alloc_buffers[dest.value()];
305 }
306
307 virtual size_t lab_waste(InCSetState value) const;
308
309 virtual void flush_stats_and_retire() ;
310 };
311
312 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP