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).
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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 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 static G1Allocator* create_allocator(G1CollectedHeap* g1h);
71
72 #ifdef ASSERT
73 // Do we currently have an active mutator region to allocate into?
74 bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; }
75 #endif
76 virtual void init_mutator_alloc_region() = 0;
77 virtual void release_mutator_alloc_region() = 0;
78
79 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
80 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0;
81 virtual void abandon_gc_alloc_regions() = 0;
82
83 // Management of retained regions.
84
85 virtual bool is_retained_old_region(HeapRegion* hr) = 0;
86 void reuse_retained_old_region(EvacuationInfo& evacuation_info,
87 OldGCAllocRegion* old,
88 HeapRegion** retained);
89
90 // Allocate blocks of memory during mutator time.
91
92 inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context);
93 inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context);
94 inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context);
95
96 size_t unsafe_max_tlab_alloc(AllocationContext_t context);
97
98 // Allocate blocks of memory during garbage collection. Will ensure an
99 // allocation region, either by picking one or expanding the
100 // heap, and then allocate a block of the given size. The block
101 // may not be a humongous - it must fit into a single heap region.
102 HeapWord* par_allocate_during_gc(InCSetState dest,
103 size_t word_size,
104 AllocationContext_t context);
105
106 HeapWord* par_allocate_during_gc(InCSetState dest,
107 size_t min_word_size,
108 size_t desired_word_size,
109 size_t* actual_word_size,
110 AllocationContext_t context);
111
112 virtual size_t used_in_alloc_regions() = 0;
113 };
114
115 // The default allocation region manager for G1. Provides a single mutator, survivor
116 // and old generation allocation region.
117 // Can retain the (single) old generation allocation region across GCs.
118 class G1DefaultAllocator : public G1Allocator {
119 private:
120 bool _survivor_is_full;
121 bool _old_is_full;
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 bool survivor_is_full(AllocationContext_t context) const;
139 virtual bool old_is_full(AllocationContext_t context) const ;
140
141 virtual void set_survivor_full(AllocationContext_t context);
142 virtual void set_old_full(AllocationContext_t context);
143
144 virtual void init_mutator_alloc_region();
145 virtual void release_mutator_alloc_region();
146
147 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info);
148 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info);
149 virtual void abandon_gc_alloc_regions();
150
151 virtual bool is_retained_old_region(HeapRegion* hr) {
152 return _retained_old_gc_alloc_region == hr;
153 }
154
155 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) {
156 return &_mutator_alloc_region;
157 }
158
159 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) {
160 return &_survivor_gc_alloc_region;
161 }
162
163 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) {
164 return &_old_gc_alloc_region;
165 }
166
167 virtual size_t used_in_alloc_regions() {
168 assert(Heap_lock->owner() != NULL,
169 "Should be owned on this thread's behalf.");
170 size_t result = 0;
171
172 // Read only once in case it is set to NULL concurrently
173 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get();
174 if (hr != NULL) {
175 result += hr->used();
176 }
177 return result;
178 }
179 };
180
181 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
182 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
183 // statistics.
184 class G1PLABAllocator : public CHeapObj<mtGC> {
185 friend class G1ParScanThreadState;
186 protected:
187 G1CollectedHeap* _g1h;
188 G1Allocator* _allocator;
189
190 // The survivor alignment in effect in bytes.
191 // == 0 : don't align survivors
192 // != 0 : align survivors to that alignment
193 // These values were chosen to favor the non-alignment case since some
194 // architectures have a special compare against zero instructions.
195 const uint _survivor_alignment_bytes;
196
197 // Number of words allocated directly (not counting PLAB allocation).
198 size_t _direct_allocated[InCSetState::Num];
199
200 virtual void flush_and_retire_stats() = 0;
201 virtual PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
202
203 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
204 // there are no restrictions on survivor alignment.
205 static uint calc_survivor_alignment_bytes() {
206 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
207 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
208 // No need to align objects in the survivors differently, return 0
209 // which means "survivor alignment is not used".
210 return 0;
211 } else {
212 assert(SurvivorAlignmentInBytes > 0, "sanity");
213 return SurvivorAlignmentInBytes;
214 }
215 }
216
217 HeapWord* allocate_new_plab(InCSetState dest,
218 size_t word_sz,
219 AllocationContext_t context);
220
221 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
222 public:
223 G1PLABAllocator(G1Allocator* allocator);
224 virtual ~G1PLABAllocator() { }
225
226 static G1PLABAllocator* create_allocator(G1Allocator* allocator);
227
228 virtual void waste(size_t& wasted, size_t& undo_wasted) = 0;
229
230 // Allocate word_sz words in dest, either directly into the regions or by
231 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
232 // not successful. Plab_refill_failed indicates whether an attempt to refill the
233 // PLAB failed or not.
234 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
235 size_t word_sz,
236 AllocationContext_t context,
237 bool* plab_refill_failed);
238
239 // Allocate word_sz words in the PLAB of dest. Returns the address of the
240 // allocated memory, NULL if not successful.
241 inline HeapWord* plab_allocate(InCSetState dest,
242 size_t word_sz,
243 AllocationContext_t context);
244
245 HeapWord* allocate(InCSetState dest,
246 size_t word_sz,
247 AllocationContext_t context,
248 bool* refill_failed) {
249 HeapWord* const obj = plab_allocate(dest, word_sz, context);
250 if (obj != NULL) {
251 return obj;
252 }
253 return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed);
254 }
255
256 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
257 };
258
259 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
260 // and old generation allocation.
261 class G1DefaultPLABAllocator : public G1PLABAllocator {
262 PLAB _surviving_alloc_buffer;
263 PLAB _tenured_alloc_buffer;
264 PLAB* _alloc_buffers[InCSetState::Num];
265
266 public:
267 G1DefaultPLABAllocator(G1Allocator* _allocator);
268
269 virtual PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
270 assert(dest.is_valid(),
271 "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value());
272 assert(_alloc_buffers[dest.value()] != NULL,
273 "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value());
274 return _alloc_buffers[dest.value()];
275 }
276
277 virtual void flush_and_retire_stats();
278
279 virtual void waste(size_t& wasted, size_t& undo_wasted);
280 };
281
282 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
283 // archive regions. This allows a quick check for whether an object
284 // should not be marked because it is in an archive region.
285 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
286 protected:
287 bool default_value() const { return false; }
288 };
289
290 // G1ArchiveAllocator is used to allocate memory in archive
291 // regions. Such regions are not scavenged nor compacted by GC.
292 // There are two types of archive regions, which are
293 // differ in the kind of references allowed for the contained objects:
294 //
295 // - 'Closed' archive region contain no references outside of other
296 // closed archive regions. The region is immutable by GC. GC does
297 // not mark object header in 'closed' archive region.
298 // - An 'open' archive region allow references to any other regions,
299 // including closed archive, open archive and other java heap regions.
300 // GC can adjust pointers and mark object header in 'open' archive region.
301 class G1ArchiveAllocator : public CHeapObj<mtGC> {
302 protected:
303 bool _open; // Indicate if the region is 'open' archive.
304 G1CollectedHeap* _g1h;
305
306 // The current allocation region
307 HeapRegion* _allocation_region;
308
309 // Regions allocated for the current archive range.
310 GrowableArray<HeapRegion*> _allocated_regions;
311
312 // The number of bytes used in the current range.
313 size_t _summary_bytes_used;
314
315 // Current allocation window within the current region.
316 HeapWord* _bottom;
317 HeapWord* _top;
318 HeapWord* _max;
319
320 // Allocate a new region for this archive allocator.
321 // Allocation is from the top of the reserved heap downward.
322 bool alloc_new_region();
323
324 public:
325 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
326 _g1h(g1h),
327 _allocation_region(NULL),
328 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
329 ResourceObj::C_HEAP),
330 2), true /* C_Heap */),
331 _summary_bytes_used(0),
332 _bottom(NULL),
333 _top(NULL),
334 _max(NULL),
335 _open(open) { }
336
337 virtual ~G1ArchiveAllocator() {
338 assert(_allocation_region == NULL, "_allocation_region not NULL");
339 }
340
341 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
342
343 // Allocate memory for an individual object.
344 HeapWord* archive_mem_allocate(size_t word_size);
345
346 // Return the memory ranges used in the current archive, after
347 // aligning to the requested alignment.
348 void complete_archive(GrowableArray<MemRegion>* ranges,
349 size_t end_alignment_in_bytes);
350
351 // The number of bytes allocated by this allocator.
352 size_t used() {
353 return _summary_bytes_used;
354 }
355
356 // Clear the count of bytes allocated in prior G1 regions. This
357 // must be done when recalculate_use is used to reset the counter
358 // for the generic allocator, since it counts bytes in all G1
359 // regions, including those still associated with this allocator.
360 void clear_used() {
361 _summary_bytes_used = 0;
362 }
363
364 // Create the _archive_region_map which is used to identify archive objects.
365 static inline void enable_archive_object_check();
366
367 // Set the regions containing the specified address range as archive/non-archive.
368 static inline void set_range_archive(MemRegion range, bool open);
369
370 // Check if the object is in closed archive
371 static inline bool is_closed_archive_object(oop object);
372 // Check if the object is in open archive
373 static inline bool is_open_archive_object(oop object);
374 // Check if the object is either in closed archive or open archive
375 static inline bool is_archive_object(oop object);
376
377 private:
378 static bool _archive_check_enabled;
379 static G1ArchiveRegionMap _closed_archive_region_map;
380 static G1ArchiveRegionMap _open_archive_region_map;
381
382 // Check if an object is in a closed archive region using the _closed_archive_region_map.
383 static inline bool in_closed_archive_range(oop object);
384 // Check if an object is in open archive region using the _open_archive_region_map.
385 static inline bool in_open_archive_range(oop object);
386
387 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
388 // unnecessarily.
389 static inline bool archive_check_enabled();
390 };
391
392 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP