1 /*
2 * Copyright (c) 2014, 2018, 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 *
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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).
14 *
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20 * or visit www.oracle.com if you need additional information or have any
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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/g1InCSetState.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "gc/shared/plab.hpp"
32
33 class EvacuationInfo;
34
35 // Interface to keep track of which regions G1 is currently allocating into. Provides
36 // some accessors (e.g. allocating into them, or getting their occupancy).
37 // Also keeps track of retained regions across GCs.
38 class G1Allocator : public CHeapObj<mtGC> {
39 friend class VMStructs;
40
41 private:
42 G1CollectedHeap* _g1h;
43
44 bool _survivor_is_full;
45 bool _old_is_full;
46
47 // Alloc region used to satisfy mutator allocation requests.
48 MutatorAllocRegion _mutator_alloc_region;
49
50 // Alloc region used to satisfy allocation requests by the GC for
51 // survivor objects.
52 SurvivorGCAllocRegion _survivor_gc_alloc_region;
53
54 // Alloc region used to satisfy allocation requests by the GC for
55 // old objects.
56 OldGCAllocRegion _old_gc_alloc_region;
57
58 HeapRegion* _retained_old_gc_alloc_region;
59
60 bool survivor_is_full() const;
61 bool old_is_full() const;
62
63 void set_survivor_full();
64 void set_old_full();
65
66 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
67 OldGCAllocRegion* old,
68 HeapRegion** retained);
69
70 // Accessors to the allocation regions.
71 inline MutatorAllocRegion* mutator_alloc_region();
72 inline SurvivorGCAllocRegion* survivor_gc_alloc_region();
73 inline OldGCAllocRegion* old_gc_alloc_region();
74
75 // Allocation attempt during GC for a survivor object / PLAB.
76 HeapWord* survivor_attempt_allocation(size_t min_word_size,
77 size_t desired_word_size,
78 size_t* actual_word_size);
79
80 // Allocation attempt during GC for an old object / PLAB.
81 HeapWord* old_attempt_allocation(size_t min_word_size,
82 size_t desired_word_size,
83 size_t* actual_word_size);
84 public:
85 G1Allocator(G1CollectedHeap* heap);
86
87 #ifdef ASSERT
88 // Do we currently have an active mutator region to allocate into?
89 bool has_mutator_alloc_region() { return mutator_alloc_region()->get() != NULL; }
90 #endif
91
92 void init_mutator_alloc_region();
93 void release_mutator_alloc_region();
94
95 void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
96 void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
97 void abandon_gc_alloc_regions();
98 bool is_retained_old_region(HeapRegion* hr);
99
100 // Allocate blocks of memory during mutator time.
101
102 inline HeapWord* attempt_allocation(size_t word_size);
103 inline HeapWord* attempt_allocation_locked(size_t word_size);
104 inline HeapWord* attempt_allocation_force(size_t word_size);
105
106 size_t unsafe_max_tlab_alloc();
107 size_t used_in_alloc_regions();
108
109 // Allocate blocks of memory during garbage collection. Will ensure an
110 // allocation region, either by picking one or expanding the
111 // heap, and then allocate a block of the given size. The block
112 // may not be a humongous - it must fit into a single heap region.
113 HeapWord* par_allocate_during_gc(InCSetState dest,
114 size_t word_size);
115
116 HeapWord* par_allocate_during_gc(InCSetState dest,
117 size_t min_word_size,
118 size_t desired_word_size,
119 size_t* actual_word_size);
120 };
121
122 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
123 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
124 // statistics.
125 class G1PLABAllocator : public CHeapObj<mtGC> {
126 friend class G1ParScanThreadState;
127 private:
128 G1CollectedHeap* _g1h;
129 G1Allocator* _allocator;
130
131 PLAB _surviving_alloc_buffer;
132 PLAB _tenured_alloc_buffer;
133 PLAB* _alloc_buffers[InCSetState::Num];
134
135 // The survivor alignment in effect in bytes.
136 // == 0 : don't align survivors
137 // != 0 : align survivors to that alignment
138 // These values were chosen to favor the non-alignment case since some
139 // architectures have a special compare against zero instructions.
140 const uint _survivor_alignment_bytes;
141
142 // Number of words allocated directly (not counting PLAB allocation).
143 size_t _direct_allocated[InCSetState::Num];
144
145 void flush_and_retire_stats();
146 inline PLAB* alloc_buffer(InCSetState dest);
147
148 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
149 // there are no restrictions on survivor alignment.
150 static uint calc_survivor_alignment_bytes();
151
152 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
153 public:
154 G1PLABAllocator(G1Allocator* allocator);
155
156 void waste(size_t& wasted, size_t& undo_wasted);
157
158 // Allocate word_sz words in dest, either directly into the regions or by
159 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
160 // not successful. Plab_refill_failed indicates whether an attempt to refill the
161 // PLAB failed or not.
162 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
163 size_t word_sz,
164 bool* plab_refill_failed);
165
166 // Allocate word_sz words in the PLAB of dest. Returns the address of the
167 // allocated memory, NULL if not successful.
168 inline HeapWord* plab_allocate(InCSetState dest,
169 size_t word_sz);
170
171 inline HeapWord* allocate(InCSetState dest,
172 size_t word_sz,
173 bool* refill_failed);
174
175 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz);
176 };
177
178 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
179 // archive regions. This allows a quick check for whether an object
180 // should not be marked because it is in an archive region.
181 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
182 protected:
183 bool default_value() const { return false; }
184 };
185
186 // G1ArchiveAllocator is used to allocate memory in archive
187 // regions. Such regions are not scavenged nor compacted by GC.
188 // There are two types of archive regions, which are
189 // differ in the kind of references allowed for the contained objects:
190 //
191 // - 'Closed' archive region contain no references outside of other
192 // closed archive regions. The region is immutable by GC. GC does
193 // not mark object header in 'closed' archive region.
194 // - An 'open' archive region allow references to any other regions,
195 // including closed archive, open archive and other java heap regions.
196 // GC can adjust pointers and mark object header in 'open' archive region.
197 class G1ArchiveAllocator : public CHeapObj<mtGC> {
198 protected:
199 bool _open; // Indicate if the region is 'open' archive.
200 G1CollectedHeap* _g1h;
201
202 // The current allocation region
203 HeapRegion* _allocation_region;
204
205 // Regions allocated for the current archive range.
206 GrowableArray<HeapRegion*> _allocated_regions;
207
208 // The number of bytes used in the current range.
209 size_t _summary_bytes_used;
210
211 // Current allocation window within the current region.
212 HeapWord* _bottom;
213 HeapWord* _top;
214 HeapWord* _max;
215
216 // Allocate a new region for this archive allocator.
217 // Allocation is from the top of the reserved heap downward.
218 bool alloc_new_region();
219
220 public:
221 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
222 _g1h(g1h),
223 _allocation_region(NULL),
224 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
225 ResourceObj::C_HEAP),
226 2), true /* C_Heap */),
227 _summary_bytes_used(0),
228 _bottom(NULL),
229 _top(NULL),
230 _max(NULL),
231 _open(open) { }
232
233 virtual ~G1ArchiveAllocator() {
234 assert(_allocation_region == NULL, "_allocation_region not NULL");
235 }
236
237 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
238
239 // Allocate memory for an individual object.
240 HeapWord* archive_mem_allocate(size_t word_size);
241
242 // Return the memory ranges used in the current archive, after
243 // aligning to the requested alignment.
244 void complete_archive(GrowableArray<MemRegion>* ranges,
245 size_t end_alignment_in_bytes);
246
247 // The number of bytes allocated by this allocator.
248 size_t used() {
249 return _summary_bytes_used;
250 }
251
252 // Clear the count of bytes allocated in prior G1 regions. This
253 // must be done when recalculate_use is used to reset the counter
254 // for the generic allocator, since it counts bytes in all G1
255 // regions, including those still associated with this allocator.
256 void clear_used() {
257 _summary_bytes_used = 0;
258 }
259
260 // Create the _archive_region_map which is used to identify archive objects.
261 static inline void enable_archive_object_check();
262
263 // Set the regions containing the specified address range as archive/non-archive.
264 static inline void set_range_archive(MemRegion range, bool open);
265
266 // Check if the object is in closed archive
267 static inline bool is_closed_archive_object(oop object);
268 // Check if the object is in open archive
269 static inline bool is_open_archive_object(oop object);
270 // Check if the object is either in closed archive or open archive
271 static inline bool is_archive_object(oop object);
272
273 private:
274 static bool _archive_check_enabled;
275 static G1ArchiveRegionMap _closed_archive_region_map;
276 static G1ArchiveRegionMap _open_archive_region_map;
277
278 // Check if an object is in a closed archive region using the _closed_archive_region_map.
279 static inline bool in_closed_archive_range(oop object);
280 // Check if an object is in open archive region using the _open_archive_region_map.
281 static inline bool in_open_archive_range(oop object);
282
283 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
284 // unnecessarily.
285 static inline bool archive_check_enabled();
286 };
287
288 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP