1 /*
2 * Copyright (c) 2014, 2019, 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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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24
25 #ifndef SHARE_GC_G1_G1ALLOCATOR_HPP
26 #define SHARE_GC_G1_G1ALLOCATOR_HPP
27
28 #include "gc/g1/g1AllocRegion.hpp"
29 #include "gc/g1/g1HeapRegionAttr.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "gc/shared/plab.hpp"
32
33 class G1EvacuationInfo;
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(G1EvacuationInfo& 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(G1EvacuationInfo& evacuation_info);
96 void release_gc_alloc_regions(G1EvacuationInfo& 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 min_word_size,
103 size_t desired_word_size,
104 size_t* actual_word_size);
105 inline HeapWord* attempt_allocation_locked(size_t word_size);
106 inline HeapWord* attempt_allocation_force(size_t word_size);
107
108 size_t unsafe_max_tlab_alloc();
109 size_t used_in_alloc_regions();
110
111 // Allocate blocks of memory during garbage collection. Will ensure an
112 // allocation region, either by picking one or expanding the
113 // heap, and then allocate a block of the given size. The block
114 // may not be a humongous - it must fit into a single heap region.
115 HeapWord* par_allocate_during_gc(G1HeapRegionAttr dest,
116 size_t word_size);
117
118 HeapWord* par_allocate_during_gc(G1HeapRegionAttr dest,
119 size_t min_word_size,
120 size_t desired_word_size,
121 size_t* actual_word_size);
122 };
123
124 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
125 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
126 // statistics.
127 class G1PLABAllocator : public CHeapObj<mtGC> {
128 friend class G1ParScanThreadState;
129 private:
130 G1CollectedHeap* _g1h;
131 G1Allocator* _allocator;
132
133 PLAB _surviving_alloc_buffer;
134 PLAB _tenured_alloc_buffer;
135 PLAB* _alloc_buffers[G1HeapRegionAttr::Num];
136
137 // The survivor alignment in effect in bytes.
138 // == 0 : don't align survivors
139 // != 0 : align survivors to that alignment
140 // These values were chosen to favor the non-alignment case since some
141 // architectures have a special compare against zero instructions.
142 const uint _survivor_alignment_bytes;
143
144 // Number of words allocated directly (not counting PLAB allocation).
145 size_t _direct_allocated[G1HeapRegionAttr::Num];
146
147 void flush_and_retire_stats();
148 inline PLAB* alloc_buffer(G1HeapRegionAttr dest);
149
150 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
151 // there are no restrictions on survivor alignment.
152 static uint calc_survivor_alignment_bytes();
153
154 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
155 public:
156 G1PLABAllocator(G1Allocator* allocator);
157
158 size_t waste() const;
159 size_t undo_waste() const;
160
161 // Allocate word_sz words in dest, either directly into the regions or by
162 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
163 // not successful. Plab_refill_failed indicates whether an attempt to refill the
164 // PLAB failed or not.
165 HeapWord* allocate_direct_or_new_plab(G1HeapRegionAttr dest,
166 size_t word_sz,
167 bool* plab_refill_failed);
168
169 // Allocate word_sz words in the PLAB of dest. Returns the address of the
170 // allocated memory, NULL if not successful.
171 inline HeapWord* plab_allocate(G1HeapRegionAttr dest,
172 size_t word_sz);
173
174 inline HeapWord* allocate(G1HeapRegionAttr dest,
175 size_t word_sz,
176 bool* refill_failed);
177
178 void undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz);
179 };
180
181 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
182 // archive regions. This allows a quick check for whether an object
183 // should not be marked because it is in an archive region.
184 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
185 protected:
186 bool default_value() const { return false; }
187 };
188
189 // G1ArchiveAllocator is used to allocate memory in archive
190 // regions. Such regions are not scavenged nor compacted by GC.
191 // There are two types of archive regions, which are
192 // differ in the kind of references allowed for the contained objects:
193 //
194 // - 'Closed' archive region contain no references outside of other
195 // closed archive regions. The region is immutable by GC. GC does
196 // not mark object header in 'closed' archive region.
197 // - An 'open' archive region allow references to any other regions,
198 // including closed archive, open archive and other java heap regions.
199 // GC can adjust pointers and mark object header in 'open' archive region.
200 class G1ArchiveAllocator : public CHeapObj<mtGC> {
201 protected:
202 bool _open; // Indicate if the region is 'open' archive.
203 G1CollectedHeap* _g1h;
204
205 // The current allocation region
206 HeapRegion* _allocation_region;
207
208 // Regions allocated for the current archive range.
209 GrowableArray<HeapRegion*> _allocated_regions;
210
211 // The number of bytes used in the current range.
212 size_t _summary_bytes_used;
213
214 // Current allocation window within the current region.
215 HeapWord* _bottom;
216 HeapWord* _top;
217 HeapWord* _max;
218
219 // Allocate a new region for this archive allocator.
220 // Allocation is from the top of the reserved heap downward.
221 bool alloc_new_region();
222
223 public:
224 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
225 _open(open),
226 _g1h(g1h),
227 _allocation_region(NULL),
228 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
229 ResourceObj::C_HEAP),
230 2), true /* C_Heap */),
231 _summary_bytes_used(0),
232 _bottom(NULL),
233 _top(NULL),
234 _max(NULL) { }
235
236 virtual ~G1ArchiveAllocator() {
237 assert(_allocation_region == NULL, "_allocation_region not NULL");
238 }
239
240 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
241
242 // Allocate memory for an individual object.
243 HeapWord* archive_mem_allocate(size_t word_size);
244
245 // Return the memory ranges used in the current archive, after
246 // aligning to the requested alignment.
247 void complete_archive(GrowableArray<MemRegion>* ranges,
248 size_t end_alignment_in_bytes);
249
250 // The number of bytes allocated by this allocator.
251 size_t used() {
252 return _summary_bytes_used;
253 }
254
255 // Clear the count of bytes allocated in prior G1 regions. This
256 // must be done when recalculate_use is used to reset the counter
257 // for the generic allocator, since it counts bytes in all G1
258 // regions, including those still associated with this allocator.
259 void clear_used() {
260 _summary_bytes_used = 0;
261 }
262
263 // Create the _archive_region_map which is used to identify archive objects.
264 static inline void enable_archive_object_check();
265
266 // Mark regions containing the specified address range as archive/non-archive.
267 static inline void set_range_archive(MemRegion range, bool open);
268 static inline void clear_range_archive(MemRegion range, bool open);
269
270 // Check if the object is in closed archive
271 static inline bool is_closed_archive_object(oop object);
272 // Check if the object is in open archive
273 static inline bool is_open_archive_object(oop object);
274 // Check if the object is either in closed archive or open archive
275 static inline bool is_archived_object(oop object);
276
277 private:
278 static bool _archive_check_enabled;
279 static G1ArchiveRegionMap _closed_archive_region_map;
280 static G1ArchiveRegionMap _open_archive_region_map;
281
282 // Check if an object is in a closed archive region using the _closed_archive_region_map.
283 static inline bool in_closed_archive_range(oop object);
284 // Check if an object is in open archive region using the _open_archive_region_map.
285 static inline bool in_open_archive_range(oop object);
286
287 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
288 // unnecessarily.
289 static inline bool archive_check_enabled();
290 };
291
292 #endif // SHARE_GC_G1_G1ALLOCATOR_HPP