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
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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).
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1ALLOCATOR_HPP
26 #define SHARE_VM_GC_G1_G1ALLOCATOR_HPP
27
28 #include "gc/g1/g1AllocRegion.hpp"
29 #include "gc/g1/g1AllocationContext.hpp"
30 #include "gc/g1/g1InCSetState.hpp"
31 #include "gc/shared/collectedHeap.hpp"
32 #include "gc/shared/plab.hpp"
33
34 class EvacuationInfo;
35
36 // Interface to keep track of which regions G1 is currently allocating into. Provides
37 // some accessors (e.g. allocating into them, or getting their occupancy).
38 // Also keeps track of retained regions across GCs.
39 class G1Allocator : public CHeapObj<mtGC> {
40 friend class VMStructs;
41 protected:
42 G1CollectedHeap* _g1h;
43
44 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0;
45
46 // Accessors to the allocation regions.
47 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
48 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0;
49
50 // Allocation attempt during GC for a survivor object / PLAB.
51 inline HeapWord* survivor_attempt_allocation(size_t word_size,
52 AllocationContext_t context);
53 // Allocation attempt during GC for an old object / PLAB.
54 inline HeapWord* old_attempt_allocation(size_t word_size,
55 AllocationContext_t context);
56 public:
57 G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { }
58 virtual ~G1Allocator() { }
59
60 static G1Allocator* create_allocator(G1CollectedHeap* g1h);
61
62 #ifdef ASSERT
63 // Do we currently have an active mutator region to allocate into?
64 bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; }
65 #endif
66 virtual void init_mutator_alloc_region() = 0;
67 virtual void release_mutator_alloc_region() = 0;
68
69 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
70 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
71 virtual void abandon_gc_alloc_regions() = 0;
72
73 // Management of retained regions.
74
75 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
76 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
77 OldGCAllocRegion* old,
78 HeapRegion** retained);
79
80 // Allocate blocks of memory during mutator time.
81
82 inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context);
83 inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context);
84 inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context);
85
86 size_t unsafe_max_tlab_alloc(AllocationContext_t context);
87
88 // Allocate blocks of memory during garbage collection. Will ensure an
89 // allocation region, either by picking one or expanding the
90 // heap, and then allocate a block of the given size. The block
91 // may not be a humongous - it must fit into a single heap region.
92 HeapWord* par_allocate_during_gc(InCSetState dest,
93 size_t word_size,
94 AllocationContext_t context);
95
96 virtual size_t used_in_alloc_regions() = 0;
97 };
98
99 // The default allocation region manager for G1. Provides a single mutator, survivor
100 // and old generation allocation region.
101 // Can retain the (single) old generation allocation region across GCs.
102 class G1DefaultAllocator : public G1Allocator {
103 protected:
104 // Alloc region used to satisfy mutator allocation requests.
105 MutatorAllocRegion _mutator_alloc_region;
106
107 // Alloc region used to satisfy allocation requests by the GC for
108 // survivor objects.
109 SurvivorGCAllocRegion _survivor_gc_alloc_region;
110
111 // Alloc region used to satisfy allocation requests by the GC for
112 // old objects.
113 OldGCAllocRegion _old_gc_alloc_region;
114
115 HeapRegion* _retained_old_gc_alloc_region;
116 public:
117 G1DefaultAllocator(G1CollectedHeap* heap) : G1Allocator(heap), _retained_old_gc_alloc_region(NULL) { }
118
119 virtual void init_mutator_alloc_region();
120 virtual void release_mutator_alloc_region();
121
122 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
123 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
124 virtual void abandon_gc_alloc_regions();
125
126 virtual bool is_retained_old_region(HeapRegion* hr) {
127 return _retained_old_gc_alloc_region == hr;
128 }
129
130 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
131 return &_mutator_alloc_region;
132 }
133
134 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
135 return &_survivor_gc_alloc_region;
136 }
137
138 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
139 return &_old_gc_alloc_region;
140 }
141
142 virtual size_t used_in_alloc_regions() {
143 assert(Heap_lock->owner() != NULL,
144 "Should be owned on this thread's behalf.");
145 size_t result = 0;
146
147 // Read only once in case it is set to NULL concurrently
148 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get();
149 if (hr != NULL) {
150 result += hr->used();
151 }
152 return result;
153 }
154 };
155
156 class G1PLAB: public PLAB {
157 private:
158 bool _retired;
159
160 public:
161 G1PLAB(size_t gclab_word_size);
162 virtual ~G1PLAB() {
163 guarantee(_retired, "Allocation buffer has not been retired");
164 }
165
166 virtual void set_buf(HeapWord* buf) {
167 PLAB::set_buf(buf);
168 _retired = false;
169 }
170
171 virtual void retire() {
172 if (_retired) {
173 return;
174 }
175 PLAB::retire();
176 _retired = true;
177 }
178
179 virtual void flush_and_retire_stats(PLABStats* stats) {
180 PLAB::flush_and_retire_stats(stats);
181 _retired = true;
182 }
183 };
184
185 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
186 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
187 // statistics.
188 class G1PLABAllocator : public CHeapObj<mtGC> {
189 friend class G1ParScanThreadState;
190 protected:
191 G1CollectedHeap* _g1h;
192 G1Allocator* _allocator;
193
194 // The survivor alignment in effect in bytes.
195 // == 0 : don't align survivors
196 // != 0 : align survivors to that alignment
197 // These values were chosen to favor the non-alignment case since some
198 // architectures have a special compare against zero instructions.
199 const uint _survivor_alignment_bytes;
200
201 virtual void retire_alloc_buffers() = 0;
202 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
203
204 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
205 // there are no restrictions on survivor alignment.
206 static uint calc_survivor_alignment_bytes() {
207 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
208 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
209 // No need to align objects in the survivors differently, return 0
210 // which means "survivor alignment is not used".
211 return 0;
212 } else {
213 assert(SurvivorAlignmentInBytes > 0, "sanity");
214 return SurvivorAlignmentInBytes;
215 }
216 }
217
218 public:
219 G1PLABAllocator(G1Allocator* allocator);
220 virtual ~G1PLABAllocator() { }
221
222 static G1PLABAllocator* create_allocator(G1Allocator* allocator);
223
224 virtual void waste(size_t& wasted, size_t& undo_wasted) = 0;
225
226 // Allocate word_sz words in dest, either directly into the regions or by
227 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
228 // not successful.
229 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
230 size_t word_sz,
231 AllocationContext_t context);
232
233 // Allocate word_sz words in the PLAB of dest. Returns the address of the
234 // allocated memory, NULL if not successful.
235 HeapWord* plab_allocate(InCSetState dest,
236 size_t word_sz,
237 AllocationContext_t context) {
238 G1PLAB* buffer = alloc_buffer(dest, context);
239 if (_survivor_alignment_bytes == 0 || !dest.is_young()) {
240 return buffer->allocate(word_sz);
241 } else {
242 return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes);
243 }
244 }
245
246 HeapWord* allocate(InCSetState dest, size_t word_sz,
247 AllocationContext_t context) {
248 HeapWord* const obj = plab_allocate(dest, word_sz, context);
249 if (obj != NULL) {
250 return obj;
251 }
252 return allocate_direct_or_new_plab(dest, word_sz, context);
253 }
254
255 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
256 };
257
258 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
259 // and old generation allocation.
260 class G1DefaultPLABAllocator : public G1PLABAllocator {
261 G1PLAB _surviving_alloc_buffer;
262 G1PLAB _tenured_alloc_buffer;
263 G1PLAB* _alloc_buffers[InCSetState::Num];
264
265 public:
266 G1DefaultPLABAllocator(G1Allocator* _allocator);
267
268 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
269 assert(dest.is_valid(),
270 err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()));
271 assert(_alloc_buffers[dest.value()] != NULL,
272 err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()));
273 return _alloc_buffers[dest.value()];
274 }
275
276 virtual void retire_alloc_buffers();
277
278 virtual void waste(size_t& wasted, size_t& undo_wasted);
279 };
280
281 // G1ArchiveAllocator is used to allocate memory in archive
282 // regions. Such regions are not modifiable by GC, being neither
283 // scavenged nor compacted, or even marked in the object header.
284 // They can contain no pointers to non-archive heap regions,
285 class G1ArchiveAllocator : public CHeapObj<mtGC> {
286
287 protected:
288 G1CollectedHeap* _g1h;
289
290 // The current allocation region
291 HeapRegion* _allocation_region;
292
293 // Regions allocated for the current archive range.
294 GrowableArray<HeapRegion*> _allocated_regions;
295
296 // The number of bytes used in the current range.
297 size_t _summary_bytes_used;
298
299 // Current allocation window within the current region.
300 HeapWord* _bottom;
301 HeapWord* _top;
302 HeapWord* _max;
303
304 // Allocate a new region for this archive allocator.
305 // Allocation is from the top of the reserved heap downward.
306 bool alloc_new_region();
307
308 public:
309 G1ArchiveAllocator(G1CollectedHeap* g1h) :
310 _g1h(g1h),
311 _allocation_region(NULL),
312 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
313 ResourceObj::C_HEAP),
314 2), true /* C_Heap */),
315 _summary_bytes_used(0),
316 _bottom(NULL),
317 _top(NULL),
318 _max(NULL) { }
319
320 virtual ~G1ArchiveAllocator() {
321 assert(_allocation_region == NULL, "_allocation_region not NULL");
322 }
323
324 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h);
325
326 // Allocate memory for an individual object.
327 HeapWord* archive_mem_allocate(size_t word_size);
328
329 // Return the memory ranges used in the current archive, after
330 // aligning to the requested alignment.
331 void complete_archive(GrowableArray<MemRegion>* ranges,
332 size_t end_alignment_in_bytes);
333
334 // The number of bytes allocated by this allocator.
335 size_t used() {
336 return _summary_bytes_used;
337 }
338
339 // Clear the count of bytes allocated in prior G1 regions. This
340 // must be done when recalculate_use is used to reset the counter
341 // for the generic allocator, since it counts bytes in all G1
342 // regions, including those still associated with this allocator.
343 void clear_used() {
344 _summary_bytes_used = 0;
345 }
346
347 };
348
349 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP