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.
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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
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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 private:
42 bool _survivor_is_full;
43 bool _old_is_full;
44 protected:
45 G1CollectedHeap* _g1h;
46
47 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0;
48
49 virtual bool survivor_is_full(AllocationContext_t context) const;
50 virtual bool old_is_full(AllocationContext_t context) const;
51
52 virtual void set_survivor_full(AllocationContext_t context);
53 virtual void set_old_full(AllocationContext_t context);
54
55 // Accessors to the allocation regions.
56 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
57 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0;
58
59 // Allocation attempt during GC for a survivor object / PLAB.
60 inline HeapWord* survivor_attempt_allocation(size_t min_word_size,
61 size_t desired_word_size,
62 size_t* actual_word_size,
63 AllocationContext_t context);
64 // Allocation attempt during GC for an old object / PLAB.
65 inline HeapWord* old_attempt_allocation(size_t min_word_size,
66 size_t desired_word_size,
67 size_t* actual_word_size,
68 AllocationContext_t context);
69 public:
70 G1Allocator(G1CollectedHeap* heap) : _g1h(heap), _survivor_is_full(false), _old_is_full(false) { }
71 virtual ~G1Allocator() { }
72
73 static G1Allocator* create_allocator(G1CollectedHeap* g1h);
74
75 #ifdef ASSERT
76 // Do we currently have an active mutator region to allocate into?
77 bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; }
78 #endif
79 virtual void init_mutator_alloc_region() = 0;
80 virtual void release_mutator_alloc_region() = 0;
81
82 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
83 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
84 virtual void abandon_gc_alloc_regions() = 0;
85
86 // Management of retained regions.
87
88 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
89 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
90 OldGCAllocRegion* old,
91 HeapRegion** retained);
92
93 // Allocate blocks of memory during mutator time.
94
95 inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context);
96 inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context);
97 inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context);
98
99 size_t unsafe_max_tlab_alloc(AllocationContext_t context);
100
101 // Allocate blocks of memory during garbage collection. Will ensure an
102 // allocation region, either by picking one or expanding the
103 // heap, and then allocate a block of the given size. The block
104 // may not be a humongous - it must fit into a single heap region.
105 HeapWord* par_allocate_during_gc(InCSetState dest,
106 size_t word_size,
107 AllocationContext_t context);
108
109 HeapWord* par_allocate_during_gc(InCSetState dest,
110 size_t min_word_size,
111 size_t desired_word_size,
112 size_t* actual_word_size,
113 AllocationContext_t context);
114
115 virtual size_t used_in_alloc_regions() = 0;
116 };
117
118 // The default allocation region manager for G1. Provides a single mutator, survivor
119 // and old generation allocation region.
120 // Can retain the (single) old generation allocation region across GCs.
121 class G1DefaultAllocator : public G1Allocator {
122 protected:
123 // Alloc region used to satisfy mutator allocation requests.
124 MutatorAllocRegion _mutator_alloc_region;
125
126 // Alloc region used to satisfy allocation requests by the GC for
127 // survivor objects.
128 SurvivorGCAllocRegion _survivor_gc_alloc_region;
129
130 // Alloc region used to satisfy allocation requests by the GC for
131 // old objects.
132 OldGCAllocRegion _old_gc_alloc_region;
133
134 HeapRegion* _retained_old_gc_alloc_region;
135 public:
136 G1DefaultAllocator(G1CollectedHeap* heap);
137
138 virtual void init_mutator_alloc_region();
139 virtual void release_mutator_alloc_region();
140
141 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
142 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
143 virtual void abandon_gc_alloc_regions();
144
145 virtual bool is_retained_old_region(HeapRegion* hr) {
146 return _retained_old_gc_alloc_region == hr;
147 }
148
149 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
150 return &_mutator_alloc_region;
151 }
152
153 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
154 return &_survivor_gc_alloc_region;
155 }
156
157 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
158 return &_old_gc_alloc_region;
159 }
160
161 virtual size_t used_in_alloc_regions() {
162 assert(Heap_lock->owner() != NULL,
163 "Should be owned on this thread's behalf.");
164 size_t result = 0;
165
166 // Read only once in case it is set to NULL concurrently
167 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get();
168 if (hr != NULL) {
169 result += hr->used();
170 }
171 return result;
172 }
173 };
174
175 class G1PLAB: public PLAB {
176 private:
177 bool _retired;
178
179 public:
180 G1PLAB(size_t gclab_word_size);
181 virtual ~G1PLAB() {
182 guarantee(_retired, "Allocation buffer has not been retired");
183 }
184
185 // The amount of space in words wasted within the PLAB including
186 // waste due to refills and alignment.
187 size_t wasted() const { return _wasted; }
188
189 virtual void set_buf(HeapWord* buf, size_t word_size) {
190 PLAB::set_buf(buf, word_size);
191 _retired = false;
192 }
193
194 virtual void retire() {
195 if (_retired) {
196 return;
197 }
198 PLAB::retire();
199 _retired = true;
200 }
201
202 virtual void flush_and_retire_stats(PLABStats* stats) {
203 PLAB::flush_and_retire_stats(stats);
204 _retired = true;
205 }
206 };
207
208 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
209 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
210 // statistics.
211 class G1PLABAllocator : public CHeapObj<mtGC> {
212 friend class G1ParScanThreadState;
213 protected:
214 G1CollectedHeap* _g1h;
215 G1Allocator* _allocator;
216
217 // The survivor alignment in effect in bytes.
218 // == 0 : don't align survivors
219 // != 0 : align survivors to that alignment
220 // These values were chosen to favor the non-alignment case since some
221 // architectures have a special compare against zero instructions.
222 const uint _survivor_alignment_bytes;
223
224 // Number of words allocated directly (not counting PLAB allocation).
225 size_t _direct_allocated[InCSetState::Num];
226
227 virtual void flush_and_retire_stats() = 0;
228 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
229
230 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
231 // there are no restrictions on survivor alignment.
232 static uint calc_survivor_alignment_bytes() {
233 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
234 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
235 // No need to align objects in the survivors differently, return 0
236 // which means "survivor alignment is not used".
237 return 0;
238 } else {
239 assert(SurvivorAlignmentInBytes > 0, "sanity");
240 return SurvivorAlignmentInBytes;
241 }
242 }
243
244 HeapWord* allocate_new_plab(InCSetState dest,
245 size_t word_sz,
246 AllocationContext_t context);
247
248 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
249 public:
250 G1PLABAllocator(G1Allocator* allocator);
251 virtual ~G1PLABAllocator() { }
252
253 static G1PLABAllocator* create_allocator(G1Allocator* allocator);
254
255 virtual void waste(size_t& wasted, size_t& undo_wasted) = 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. Plab_refill_failed indicates whether an attempt to refill the
260 // PLAB failed or not.
261 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
262 size_t word_sz,
263 AllocationContext_t context,
264 bool* plab_refill_failed);
265
266 // Allocate word_sz words in the PLAB of dest. Returns the address of the
267 // allocated memory, NULL if not successful.
268 inline HeapWord* plab_allocate(InCSetState dest,
269 size_t word_sz,
270 AllocationContext_t context);
271
272 HeapWord* allocate(InCSetState dest,
273 size_t word_sz,
274 AllocationContext_t context,
275 bool* refill_failed) {
276 HeapWord* const obj = plab_allocate(dest, word_sz, context);
277 if (obj != NULL) {
278 return obj;
279 }
280 return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed);
281 }
282
283 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
284 };
285
286 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
287 // and old generation allocation.
288 class G1DefaultPLABAllocator : public G1PLABAllocator {
289 G1PLAB _surviving_alloc_buffer;
290 G1PLAB _tenured_alloc_buffer;
291 G1PLAB* _alloc_buffers[InCSetState::Num];
292
293 public:
294 G1DefaultPLABAllocator(G1Allocator* _allocator);
295
296 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
297 assert(dest.is_valid(),
298 "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value());
299 assert(_alloc_buffers[dest.value()] != NULL,
300 "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value());
301 return _alloc_buffers[dest.value()];
302 }
303
304 virtual void flush_and_retire_stats();
305
306 virtual void waste(size_t& wasted, size_t& undo_wasted);
307 };
308
309 // G1ArchiveAllocator is used to allocate memory in archive
310 // regions. Such regions are not modifiable by GC, being neither
311 // scavenged nor compacted, or even marked in the object header.
312 // They can contain no pointers to non-archive heap regions,
313 class G1ArchiveAllocator : public CHeapObj<mtGC> {
314
315 protected:
316 G1CollectedHeap* _g1h;
317
318 // The current allocation region
319 HeapRegion* _allocation_region;
320
321 // Regions allocated for the current archive range.
322 GrowableArray<HeapRegion*> _allocated_regions;
323
324 // The number of bytes used in the current range.
325 size_t _summary_bytes_used;
326
327 // Current allocation window within the current region.
328 HeapWord* _bottom;
329 HeapWord* _top;
330 HeapWord* _max;
331
332 // Allocate a new region for this archive allocator.
333 // Allocation is from the top of the reserved heap downward.
334 bool alloc_new_region();
335
336 public:
337 G1ArchiveAllocator(G1CollectedHeap* g1h) :
338 _g1h(g1h),
339 _allocation_region(NULL),
340 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
341 ResourceObj::C_HEAP),
342 2), true /* C_Heap */),
343 _summary_bytes_used(0),
344 _bottom(NULL),
345 _top(NULL),
346 _max(NULL) { }
347
348 virtual ~G1ArchiveAllocator() {
349 assert(_allocation_region == NULL, "_allocation_region not NULL");
350 }
351
352 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h);
353
354 // Allocate memory for an individual object.
355 HeapWord* archive_mem_allocate(size_t word_size);
356
357 // Return the memory ranges used in the current archive, after
358 // aligning to the requested alignment.
359 void complete_archive(GrowableArray<MemRegion>* ranges,
360 size_t end_alignment_in_bytes);
361
362 // The number of bytes allocated by this allocator.
363 size_t used() {
364 return _summary_bytes_used;
365 }
366
367 // Clear the count of bytes allocated in prior G1 regions. This
368 // must be done when recalculate_use is used to reset the counter
369 // for the generic allocator, since it counts bytes in all G1
370 // regions, including those still associated with this allocator.
371 void clear_used() {
372 _summary_bytes_used = 0;
373 }
374
375 };
376
377 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP