1 /*
2 * Copyright (c) 2014, 2017, 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
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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 virtual bool survivor_is_full(AllocationContext_t context) const = 0;
47 virtual bool old_is_full(AllocationContext_t context) const = 0;
48
49 virtual void set_survivor_full(AllocationContext_t context) = 0;
50 virtual void set_old_full(AllocationContext_t context) = 0;
51
52 // Accessors to the allocation regions.
53 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0;
54 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0;
55
56 // Allocation attempt during GC for a survivor object / PLAB.
57 inline HeapWord* survivor_attempt_allocation(size_t min_word_size,
58 size_t desired_word_size,
59 size_t* actual_word_size,
60 AllocationContext_t context);
61 // Allocation attempt during GC for an old object / PLAB.
62 inline HeapWord* old_attempt_allocation(size_t min_word_size,
63 size_t desired_word_size,
64 size_t* actual_word_size,
65 AllocationContext_t context);
66 public:
67 G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { }
68 virtual ~G1Allocator() { }
69
70 #ifdef ASSERT
71 // Do we currently have an active mutator region to allocate into?
72 bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; }
73 #endif
74 virtual void init_mutator_alloc_region() = 0;
75 virtual void release_mutator_alloc_region() = 0;
76
77 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
78 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
79 virtual void abandon_gc_alloc_regions() = 0;
80
81 // Management of retained regions.
82
83 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
84 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
85 OldGCAllocRegion* old,
86 HeapRegion** retained);
87
88 // Allocate blocks of memory during mutator time.
89
90 inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context);
91 inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context);
92 inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context);
93
94 size_t unsafe_max_tlab_alloc(AllocationContext_t context);
95
96 // Allocate blocks of memory during garbage collection. Will ensure an
97 // allocation region, either by picking one or expanding the
98 // heap, and then allocate a block of the given size. The block
99 // may not be a humongous - it must fit into a single heap region.
100 HeapWord* par_allocate_during_gc(InCSetState dest,
101 size_t word_size,
102 AllocationContext_t context);
103
104 HeapWord* par_allocate_during_gc(InCSetState dest,
105 size_t min_word_size,
106 size_t desired_word_size,
107 size_t* actual_word_size,
108 AllocationContext_t context);
109
110 virtual size_t used_in_alloc_regions() = 0;
111 };
112
113 // The default allocation region manager for G1. Provides a single mutator, survivor
114 // and old generation allocation region.
115 // Can retain the (single) old generation allocation region across GCs.
116 class G1DefaultAllocator : public G1Allocator {
117 private:
118 bool _survivor_is_full;
119 bool _old_is_full;
120 protected:
121 // Alloc region used to satisfy mutator allocation requests.
122 MutatorAllocRegion _mutator_alloc_region;
123
124 // Alloc region used to satisfy allocation requests by the GC for
125 // survivor objects.
126 SurvivorGCAllocRegion _survivor_gc_alloc_region;
127
128 // Alloc region used to satisfy allocation requests by the GC for
129 // old objects.
130 OldGCAllocRegion _old_gc_alloc_region;
131
132 HeapRegion* _retained_old_gc_alloc_region;
133 public:
134 G1DefaultAllocator(G1CollectedHeap* heap);
135
136 virtual bool survivor_is_full(AllocationContext_t context) const;
137 virtual bool old_is_full(AllocationContext_t context) const ;
138
139 virtual void set_survivor_full(AllocationContext_t context);
140 virtual void set_old_full(AllocationContext_t context);
141
142 virtual void init_mutator_alloc_region();
143 virtual void release_mutator_alloc_region();
144
145 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
146 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
147 virtual void abandon_gc_alloc_regions();
148
149 virtual bool is_retained_old_region(HeapRegion* hr) {
150 return _retained_old_gc_alloc_region == hr;
151 }
152
153 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
154 return &_mutator_alloc_region;
155 }
156
157 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
158 return &_survivor_gc_alloc_region;
159 }
160
161 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
162 return &_old_gc_alloc_region;
163 }
164
165 virtual size_t used_in_alloc_regions() {
166 assert(Heap_lock->owner() != NULL,
167 "Should be owned on this thread's behalf.");
168 size_t result = 0;
169
170 // Read only once in case it is set to NULL concurrently
171 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get();
172 if (hr != NULL) {
173 result += hr->used();
174 }
175 return result;
176 }
177 };
178
179 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
180 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
181 // statistics.
182 class G1PLABAllocator : public CHeapObj<mtGC> {
183 friend class G1ParScanThreadState;
184 protected:
185 G1CollectedHeap* _g1h;
186 G1Allocator* _allocator;
187
188 // The survivor alignment in effect in bytes.
189 // == 0 : don't align survivors
190 // != 0 : align survivors to that alignment
191 // These values were chosen to favor the non-alignment case since some
192 // architectures have a special compare against zero instructions.
193 const uint _survivor_alignment_bytes;
194
195 // Number of words allocated directly (not counting PLAB allocation).
196 size_t _direct_allocated[InCSetState::Num];
197
198 virtual void flush_and_retire_stats() = 0;
199 virtual PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
200
201 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
202 // there are no restrictions on survivor alignment.
203 static uint calc_survivor_alignment_bytes() {
204 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
205 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
206 // No need to align objects in the survivors differently, return 0
207 // which means "survivor alignment is not used".
208 return 0;
209 } else {
210 assert(SurvivorAlignmentInBytes > 0, "sanity");
211 return SurvivorAlignmentInBytes;
212 }
213 }
214
215 HeapWord* allocate_new_plab(InCSetState dest,
216 size_t word_sz,
217 AllocationContext_t context);
218
219 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
220 public:
221 G1PLABAllocator(G1Allocator* allocator);
222 virtual ~G1PLABAllocator() { }
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. Plab_refill_failed indicates whether an attempt to refill the
229 // PLAB failed or not.
230 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
231 size_t word_sz,
232 AllocationContext_t context,
233 bool* plab_refill_failed);
234
235 // Allocate word_sz words in the PLAB of dest. Returns the address of the
236 // allocated memory, NULL if not successful.
237 inline HeapWord* plab_allocate(InCSetState dest,
238 size_t word_sz,
239 AllocationContext_t context);
240
241 HeapWord* allocate(InCSetState dest,
242 size_t word_sz,
243 AllocationContext_t context,
244 bool* refill_failed) {
245 HeapWord* const obj = plab_allocate(dest, word_sz, context);
246 if (obj != NULL) {
247 return obj;
248 }
249 return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed);
250 }
251
252 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
253 };
254
255 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
256 // and old generation allocation.
257 class G1DefaultPLABAllocator : public G1PLABAllocator {
258 PLAB _surviving_alloc_buffer;
259 PLAB _tenured_alloc_buffer;
260 PLAB* _alloc_buffers[InCSetState::Num];
261
262 public:
263 G1DefaultPLABAllocator(G1Allocator* _allocator);
264
265 virtual PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
266 assert(dest.is_valid(),
267 "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value());
268 assert(_alloc_buffers[dest.value()] != NULL,
269 "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value());
270 return _alloc_buffers[dest.value()];
271 }
272
273 virtual void flush_and_retire_stats();
274
275 virtual void waste(size_t& wasted, size_t& undo_wasted);
276 };
277
278 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
279 // archive regions. This allows a quick check for whether an object
280 // should not be marked because it is in an archive region.
281 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
282 protected:
283 bool default_value() const { return false; }
284 };
285
286 // G1ArchiveAllocator is used to allocate memory in archive
287 // regions. Such regions are not scavenged nor compacted by GC.
288 // There are two types of archive regions, which are
289 // differ in the kind of references allowed for the contained objects:
290 //
291 // - 'Closed' archive region contain no references outside of other
292 // closed archive regions. The region is immutable by GC. GC does
293 // not mark object header in 'closed' archive region.
294 // - An 'open' archive region allow references to any other regions,
295 // including closed archive, open archive and other java heap regions.
296 // GC can adjust pointers and mark object header in 'open' archive region.
297 class G1ArchiveAllocator : public CHeapObj<mtGC> {
298 protected:
299 bool _open; // Indicate if the region is 'open' archive.
300 G1CollectedHeap* _g1h;
301
302 // The current allocation region
303 HeapRegion* _allocation_region;
304
305 // Regions allocated for the current archive range.
306 GrowableArray<HeapRegion*> _allocated_regions;
307
308 // The number of bytes used in the current range.
309 size_t _summary_bytes_used;
310
311 // Current allocation window within the current region.
312 HeapWord* _bottom;
313 HeapWord* _top;
314 HeapWord* _max;
315
316 // Allocate a new region for this archive allocator.
317 // Allocation is from the top of the reserved heap downward.
318 bool alloc_new_region();
319
320 public:
321 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
322 _g1h(g1h),
323 _allocation_region(NULL),
324 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
325 ResourceObj::C_HEAP),
326 2), true /* C_Heap */),
327 _summary_bytes_used(0),
328 _bottom(NULL),
329 _top(NULL),
330 _max(NULL),
331 _open(open) { }
332
333 virtual ~G1ArchiveAllocator() {
334 assert(_allocation_region == NULL, "_allocation_region not NULL");
335 }
336
337 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
338
339 // Allocate memory for an individual object.
340 HeapWord* archive_mem_allocate(size_t word_size);
341
342 // Return the memory ranges used in the current archive, after
343 // aligning to the requested alignment.
344 void complete_archive(GrowableArray<MemRegion>* ranges,
345 size_t end_alignment_in_bytes);
346
347 // The number of bytes allocated by this allocator.
348 size_t used() {
349 return _summary_bytes_used;
350 }
351
352 // Clear the count of bytes allocated in prior G1 regions. This
353 // must be done when recalculate_use is used to reset the counter
354 // for the generic allocator, since it counts bytes in all G1
355 // regions, including those still associated with this allocator.
356 void clear_used() {
357 _summary_bytes_used = 0;
358 }
359
360 // Create the _archive_region_map which is used to identify archive objects.
361 static inline void enable_archive_object_check();
362
363 // Set the regions containing the specified address range as archive/non-archive.
364 static inline void set_range_archive(MemRegion range, bool open);
365
366 // Check if the object is in closed archive
367 static inline bool is_closed_archive_object(oop object);
368 // Check if the object is in open archive
369 static inline bool is_open_archive_object(oop object);
370 // Check if the object is either in closed archive or open archive
371 static inline bool is_archive_object(oop object);
372
373 private:
374 static bool _archive_check_enabled;
375 static G1ArchiveRegionMap _closed_archive_region_map;
376 static G1ArchiveRegionMap _open_archive_region_map;
377
378 // Check if an object is in a closed archive region using the _closed_archive_region_map.
379 static inline bool in_closed_archive_range(oop object);
380 // Check if an object is in open archive region using the _open_archive_region_map.
381 static inline bool in_open_archive_range(oop object);
382
383 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
384 // unnecessarily.
385 static inline bool archive_check_enabled();
386 };
387
388 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP