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
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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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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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 class G1PLAB: public PLAB {
182 private:
183 bool _retired;
184
185 public:
186 G1PLAB(size_t gclab_word_size);
187 virtual ~G1PLAB() {
188 guarantee(_retired, "Allocation buffer has not been retired");
189 }
190
191 // The amount of space in words wasted within the PLAB including
192 // waste due to refills and alignment.
193 size_t wasted() const { return _wasted; }
194
195 virtual void set_buf(HeapWord* buf, size_t word_size) {
196 PLAB::set_buf(buf, word_size);
197 _retired = false;
198 }
199
200 virtual void retire() {
201 if (_retired) {
202 return;
203 }
204 PLAB::retire();
205 _retired = true;
206 }
207
208 virtual void flush_and_retire_stats(PLABStats* stats) {
209 PLAB::flush_and_retire_stats(stats);
210 _retired = true;
211 }
212 };
213
214 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs.
215 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some
216 // statistics.
217 class G1PLABAllocator : public CHeapObj<mtGC> {
218 friend class G1ParScanThreadState;
219 protected:
220 G1CollectedHeap* _g1h;
221 G1Allocator* _allocator;
222
223 // The survivor alignment in effect in bytes.
224 // == 0 : don't align survivors
225 // != 0 : align survivors to that alignment
226 // These values were chosen to favor the non-alignment case since some
227 // architectures have a special compare against zero instructions.
228 const uint _survivor_alignment_bytes;
229
230 // Number of words allocated directly (not counting PLAB allocation).
231 size_t _direct_allocated[InCSetState::Num];
232
233 virtual void flush_and_retire_stats() = 0;
234 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0;
235
236 // Calculate the survivor space object alignment in bytes. Returns that or 0 if
237 // there are no restrictions on survivor alignment.
238 static uint calc_survivor_alignment_bytes() {
239 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity");
240 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) {
241 // No need to align objects in the survivors differently, return 0
242 // which means "survivor alignment is not used".
243 return 0;
244 } else {
245 assert(SurvivorAlignmentInBytes > 0, "sanity");
246 return SurvivorAlignmentInBytes;
247 }
248 }
249
250 HeapWord* allocate_new_plab(InCSetState dest,
251 size_t word_sz,
252 AllocationContext_t context);
253
254 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const;
255 public:
256 G1PLABAllocator(G1Allocator* allocator);
257 virtual ~G1PLABAllocator() { }
258
259 static G1PLABAllocator* create_allocator(G1Allocator* allocator);
260
261 virtual void waste(size_t& wasted, size_t& undo_wasted) = 0;
262
263 // Allocate word_sz words in dest, either directly into the regions or by
264 // allocating a new PLAB. Returns the address of the allocated memory, NULL if
265 // not successful. Plab_refill_failed indicates whether an attempt to refill the
266 // PLAB failed or not.
267 HeapWord* allocate_direct_or_new_plab(InCSetState dest,
268 size_t word_sz,
269 AllocationContext_t context,
270 bool* plab_refill_failed);
271
272 // Allocate word_sz words in the PLAB of dest. Returns the address of the
273 // allocated memory, NULL if not successful.
274 inline HeapWord* plab_allocate(InCSetState dest,
275 size_t word_sz,
276 AllocationContext_t context);
277
278 HeapWord* allocate(InCSetState dest,
279 size_t word_sz,
280 AllocationContext_t context,
281 bool* refill_failed) {
282 HeapWord* const obj = plab_allocate(dest, word_sz, context);
283 if (obj != NULL) {
284 return obj;
285 }
286 return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed);
287 }
288
289 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context);
290 };
291
292 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor
293 // and old generation allocation.
294 class G1DefaultPLABAllocator : public G1PLABAllocator {
295 G1PLAB _surviving_alloc_buffer;
296 G1PLAB _tenured_alloc_buffer;
297 G1PLAB* _alloc_buffers[InCSetState::Num];
298
299 public:
300 G1DefaultPLABAllocator(G1Allocator* _allocator);
301
302 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) {
303 assert(dest.is_valid(),
304 "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value());
305 assert(_alloc_buffers[dest.value()] != NULL,
306 "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value());
307 return _alloc_buffers[dest.value()];
308 }
309
310 virtual void flush_and_retire_stats();
311
312 virtual void waste(size_t& wasted, size_t& undo_wasted);
313 };
314
315 // G1ArchiveRegionMap is a boolean array used to mark G1 regions as
316 // archive regions. This allows a quick check for whether an object
317 // should not be marked because it is in an archive region.
318 class G1ArchiveRegionMap : public G1BiasedMappedArray<bool> {
319 protected:
320 bool default_value() const { return false; }
321 };
322
323 // G1ArchiveAllocator is used to allocate memory in archive
324 // regions. Such regions are not scavenged nor compacted by GC.
325 // There are two types of archive regions, which are
326 // differ in the kind of references allowed for the contained objects:
327 //
328 // - 'Closed' archive region contain no references outside of archive
329 // regions. The region is immutable by GC. GC does not mark object
330 // header in 'closed' archive region.
331 // - An 'open' archive region may contain references pointing to
332 // non-archive heap region. GC can adjust pointers and mark object
333 // header in 'open' archive region.
334 class G1ArchiveAllocator : public CHeapObj<mtGC> {
335 protected:
336 bool _open; // Indicate if the region is 'open' archive.
337 G1CollectedHeap* _g1h;
338
339 // The current allocation region
340 HeapRegion* _allocation_region;
341
342 // Regions allocated for the current archive range.
343 GrowableArray<HeapRegion*> _allocated_regions;
344
345 // The number of bytes used in the current range.
346 size_t _summary_bytes_used;
347
348 // Current allocation window within the current region.
349 HeapWord* _bottom;
350 HeapWord* _top;
351 HeapWord* _max;
352
353 // Allocate a new region for this archive allocator.
354 // Allocation is from the top of the reserved heap downward.
355 bool alloc_new_region();
356
357 public:
358 G1ArchiveAllocator(G1CollectedHeap* g1h, bool open) :
359 _g1h(g1h),
360 _allocation_region(NULL),
361 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions,
362 ResourceObj::C_HEAP),
363 2), true /* C_Heap */),
364 _summary_bytes_used(0),
365 _bottom(NULL),
366 _top(NULL),
367 _max(NULL),
368 _open(open) { }
369
370 virtual ~G1ArchiveAllocator() {
371 assert(_allocation_region == NULL, "_allocation_region not NULL");
372 }
373
374 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h, bool open);
375
376 // Allocate memory for an individual object.
377 HeapWord* archive_mem_allocate(size_t word_size);
378
379 // Return the memory ranges used in the current archive, after
380 // aligning to the requested alignment.
381 void complete_archive(GrowableArray<MemRegion>* ranges,
382 size_t end_alignment_in_bytes);
383
384 // The number of bytes allocated by this allocator.
385 size_t used() {
386 return _summary_bytes_used;
387 }
388
389 // Clear the count of bytes allocated in prior G1 regions. This
390 // must be done when recalculate_use is used to reset the counter
391 // for the generic allocator, since it counts bytes in all G1
392 // regions, including those still associated with this allocator.
393 void clear_used() {
394 _summary_bytes_used = 0;
395 }
396
397 // Create the _archive_region_map which is used to identify archive objects.
398 static inline void enable_archive_object_check();
399
400 // Set the regions containing the specified address range as archive/non-archive.
401 static inline void set_range_archive(MemRegion range, bool open);
402
403 // Check if the object is in closed archive
404 static inline bool is_closed_archive_object(oop object);
405 // Check if the object is in open archive
406 static inline bool is_open_archive_object(oop object);
407 // Check if the object is either in closed archive or open archive
408 static inline bool is_archive_object(oop object);
409
410 private:
411 static bool _archive_check_enabled;
412 static G1ArchiveRegionMap _closed_archive_region_map;
413 static G1ArchiveRegionMap _open_archive_region_map;
414
415 // Check if an object is in a closed archive region using the _closed_archive_region_map.
416 static inline bool in_closed_archive_range(oop object);
417 // Check if an object is in open archive region using the _open_archive_region_map.
418 static inline bool in_open_archive_range(oop object);
419
420 // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
421 // unnecessarily.
422 static inline bool archive_check_enabled();
423 };
424
425 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP