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.
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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).
14 *
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
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 class G1NUMA;
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
42 private:
43 G1CollectedHeap* _g1h;
44 G1NUMA* _numa;
45
46 bool _survivor_is_full;
47 bool _old_is_full;
48
49 // The number of MutatorAllocRegions used, one per memory node.
50 size_t _num_alloc_regions;
51
52 // Alloc region used to satisfy mutator allocation requests.
53 MutatorAllocRegion* _mutator_alloc_regions;
54
55 // Alloc region used to satisfy allocation requests by the GC for
56 // survivor objects.
57 SurvivorGCAllocRegion* _survivor_gc_alloc_regions;
58
59 // Alloc region used to satisfy allocation requests by the GC for
60 // old objects.
61 OldGCAllocRegion _old_gc_alloc_region;
62
63 HeapRegion* _retained_old_gc_alloc_region;
64
65 bool survivor_is_full() const;
66 bool old_is_full() const;
67
68 void set_survivor_full();
69 void set_old_full();
70
71 void reuse_retained_old_region(G1EvacuationInfo& evacuation_info,
72 OldGCAllocRegion* old,
73 HeapRegion** retained);
74
75 // Accessors to the allocation regions.
76 inline MutatorAllocRegion* mutator_alloc_region(uint node_index);
77 inline SurvivorGCAllocRegion* survivor_gc_alloc_region(uint node_index);
78 inline OldGCAllocRegion* old_gc_alloc_region();
79
80 // Allocation attempt during GC for a survivor object / PLAB.
81 HeapWord* survivor_attempt_allocation(size_t min_word_size,
82 size_t desired_word_size,
83 size_t* actual_word_size,
84 uint node_index);
85
86 // Allocation attempt during GC for an old object / PLAB.
87 HeapWord* old_attempt_allocation(size_t min_word_size,
88 size_t desired_word_size,
89 size_t* actual_word_size);
90
91 // Node index of current thread.
92 inline uint current_node_index() const;
93
94 public:
95 G1Allocator(G1CollectedHeap* heap);
96 ~G1Allocator();
97
98 uint num_nodes() { return (uint)_num_alloc_regions; }
99
100 #ifdef ASSERT
101 // Do we currently have an active mutator region to allocate into?
102 bool has_mutator_alloc_region();
103 #endif
104
105 void init_mutator_alloc_regions();
106 void release_mutator_alloc_regions();
107
108 void init_gc_alloc_regions(G1EvacuationInfo& evacuation_info);
109 void release_gc_alloc_regions(G1EvacuationInfo& evacuation_info);
110 void abandon_gc_alloc_regions();
111 bool is_retained_old_region(HeapRegion* hr);
112
113 // Allocate blocks of memory during mutator time.
114
115 inline HeapWord* attempt_allocation(size_t min_word_size,
116 size_t desired_word_size,
117 size_t* actual_word_size);
118 inline HeapWord* attempt_allocation_locked(size_t word_size);
119 inline HeapWord* attempt_allocation_force(size_t word_size);
120
121 size_t unsafe_max_tlab_alloc();
122 size_t used_in_alloc_regions();
123
124 // Allocate blocks of memory during garbage collection. Will ensure an
125 // allocation region, either by picking one or expanding the
126 // heap, and then allocate a block of the given size. The block
127 // may not be a humongous - it must fit into a single heap region.
128 HeapWord* par_allocate_during_gc(G1HeapRegionAttr dest,
129 size_t word_size,
130 uint node_index);
131
132 HeapWord* par_allocate_during_gc(G1HeapRegionAttr dest,
133 size_t min_word_size,
134 size_t desired_word_size,
135 size_t* actual_word_size,
136 uint node_index);
137 };
138
139 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
140 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
141 // statistics.
142 class G1PLABAllocator : public CHeapObj<mtGC> {
143 friend class G1ParScanThreadState;
144 private:
145 typedef G1HeapRegionAttr::region_type_t region_type_t;
146
147 G1CollectedHeap* _g1h;
148 G1Allocator* _allocator;
149
150 PLAB** _alloc_buffers[G1HeapRegionAttr::Num];
151
152 // The survivor alignment in effect in bytes.
153 // == 0 : don't align survivors
154 // != 0 : align survivors to that alignment
155 // These values were chosen to favor the non-alignment case since some
156 // architectures have a special compare against zero instructions.
157 const uint _survivor_alignment_bytes;
158
159 // Number of words allocated directly (not counting PLAB allocation).
160 size_t _direct_allocated[G1HeapRegionAttr::Num];
161
162 void flush_and_retire_stats();
163 inline PLAB* alloc_buffer(G1HeapRegionAttr dest, uint node_index) const;
164 inline PLAB* alloc_buffer(region_type_t dest, uint node_index) const;
165
166 // Returns the number of allocation buffers for the given dest.
167 // There is only 1 buffer for Old while Young may have multiple buffers depending on
168 // active NUMA nodes.
169 inline uint alloc_buffers_length(region_type_t dest) const;
170
171 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
172 // there are no restrictions on survivor alignment.
173 static uint calc_survivor_alignment_bytes();
174
175 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
176 public:
177 G1PLABAllocator(G1Allocator* allocator);
178 ~G1PLABAllocator();
179
180 size_t waste() const;
181 size_t undo_waste() const;
182
183 // Allocate word_sz words in dest, either directly into the regions or by
184 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
185 // not successful. Plab_refill_failed indicates whether an attempt to refill the
186 // PLAB failed or not.
187 HeapWord* allocate_direct_or_new_plab(G1HeapRegionAttr dest,
188 size_t word_sz,
189 bool* plab_refill_failed,
190 uint node_index);
191
192 // Allocate word_sz words in the PLAB of dest. Returns the address of the
193 // allocated memory, NULL if not successful.
194 inline HeapWord* plab_allocate(G1HeapRegionAttr dest,
195 size_t word_sz,
196 uint node_index);
197
198 inline HeapWord* allocate(G1HeapRegionAttr dest,
199 size_t word_sz,
200 bool* refill_failed,
201 uint node_index);
202
203 void undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz, uint node_index);
204 };
205
206 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
207 // archive regions. This allows a quick check for whether an object
208 // should not be marked because it is in an archive region.
209 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
210 protected:
211 bool default_value() const { return false; }
212 };
213
214 // G1ArchiveAllocator is used to allocate memory in archive
215 // regions. Such regions are not scavenged nor compacted by GC.
216 // There are two types of archive regions, which are
217 // differ in the kind of references allowed for the contained objects:
218 //
219 // - 'Closed' archive region contain no references outside of other
220 // closed archive regions. The region is immutable by GC. GC does
221 // not mark object header in 'closed' archive region.
222 // - An 'open' archive region allow references to any other regions,
223 // including closed archive, open archive and other java heap regions.
224 // GC can adjust pointers and mark object header in 'open' archive region.
225 class G1ArchiveAllocator : public CHeapObj<mtGC> {
226 protected:
227 bool _open; // Indicate if the region is 'open' archive.
228 G1CollectedHeap* _g1h;
229
230 // The current allocation region
231 HeapRegion* _allocation_region;
232
233 // Regions allocated for the current archive range.
234 GrowableArray<HeapRegion*> _allocated_regions;
235
236 // The number of bytes used in the current range.
237 size_t _summary_bytes_used;
238
239 // Current allocation window within the current region.
240 HeapWord* _bottom;
241 HeapWord* _top;
242 HeapWord* _max;
243
244 // Allocate a new region for this archive allocator.
245 // Allocation is from the top of the reserved heap downward.
246 bool alloc_new_region();
247
248 public:
249 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
250 _open(open),
251 _g1h(g1h),
252 _allocation_region(NULL),
253 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
254 ResourceObj::C_HEAP),
255 2), true /* C_Heap */),
256 _summary_bytes_used(0),
257 _bottom(NULL),
258 _top(NULL),
259 _max(NULL) { }
260
261 virtual ~G1ArchiveAllocator() {
262 assert(_allocation_region == NULL, "_allocation_region not NULL");
263 }
264
265 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
266
267 // Allocate memory for an individual object.
268 HeapWord* archive_mem_allocate(size_t word_size);
269
270 // Return the memory ranges used in the current archive, after
271 // aligning to the requested alignment.
272 void complete_archive(GrowableArray<MemRegion>* ranges,
273 size_t end_alignment_in_bytes);
274
275 // The number of bytes allocated by this allocator.
276 size_t used() {
277 return _summary_bytes_used;
278 }
279
280 // Clear the count of bytes allocated in prior G1 regions. This
281 // must be done when recalculate_use is used to reset the counter
282 // for the generic allocator, since it counts bytes in all G1
283 // regions, including those still associated with this allocator.
284 void clear_used() {
285 _summary_bytes_used = 0;
286 }
287
288 // Create the _archive_region_map which is used to identify archive objects.
289 static inline void enable_archive_object_check();
290
291 // Mark regions containing the specified address range as archive/non-archive.
292 static inline void set_range_archive(MemRegion range, bool open);
293 static inline void clear_range_archive(MemRegion range, bool open);
294
295 // Check if the object is in closed archive
296 static inline bool is_closed_archive_object(oop object);
297 // Check if the object is in open archive
298 static inline bool is_open_archive_object(oop object);
299 // Check if the object is either in closed archive or open archive
300 static inline bool is_archived_object(oop object);
301
302 private:
303 static bool _archive_check_enabled;
304 static G1ArchiveRegionMap _closed_archive_region_map;
305 static G1ArchiveRegionMap _open_archive_region_map;
306
307 // Check if an object is in a closed archive region using the _closed_archive_region_map.
308 static inline bool in_closed_archive_range(oop object);
309 // Check if an object is in open archive region using the _open_archive_region_map.
310 static inline bool in_open_archive_range(oop object);
311
312 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
313 // unnecessarily.
314 static inline bool archive_check_enabled();
315 };
316
317 #endif // SHARE_GC_G1_G1ALLOCATOR_HPP