1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
26
27 #include "gc/shared/space.hpp"
28 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
29 #include "gc/shenandoah/shenandoahAsserts.hpp"
30 #include "gc/shenandoah/shenandoahHeap.hpp"
31 #include "gc/shenandoah/shenandoahPacer.hpp"
32 #include "memory/universe.hpp"
33 #include "utilities/sizes.hpp"
34
35 class VMStructs;
36 class ShenandoahHeapRegionStateConstant;
37
38 class ShenandoahHeapRegion : public ContiguousSpace {
39 friend class VMStructs;
40 friend class ShenandoahHeapRegionStateConstant;
41 private:
42 /*
43 Region state is described by a state machine. Transitions are guarded by
44 heap lock, which allows changing the state of several regions atomically.
45 Region states can be logically aggregated in groups.
46
47 "Empty":
48 .................................................................
49 . .
50 . .
51 . Uncommitted <------- Committed <------------------------\
52 . | | . |
53 . \---------v-----------/ . |
54 . | . |
55 .........................|....................................... |
56 | |
57 "Active": | |
58 .........................|....................................... |
59 . | . |
60 . /-----------------^-------------------\ . |
61 . | | . |
62 . v v "Humongous": . |
63 . Regular ---\-----\ ..................O................ . |
64 . | ^ | | . | . . |
65 . | | | | . *---------\ . . |
66 . v | | | . v v . . |
67 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
68 . ^ / | | . Pinned v | . . |
69 . | / | | . *<--------/ . . |
70 . | v | | . | . . |
71 . CsetPinned | | ..................O................ . |
72 . | | | . |
73 . \-----\---v-------------------/ . |
74 . | . |
75 .........................|....................................... |
76 | |
77 "Trash": | |
78 .........................|....................................... |
79 . | . |
80 . v . |
81 . Trash ---------------------------------------/
82 . .
83 . .
84 .................................................................
85
86 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
87 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
88
89 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
90 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
91 quick reclamation without actual cleaning up.
92
93 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
94 Can be done asynchronously and in bulk.
95
96 Note how internal transitions disallow logic bugs:
97 a) No region can go Empty, unless properly reclaimed/recycled;
98 b) No region can go Uncommitted, unless reclaimed/recycled first;
99 c) Only Regular regions can go to CSet;
100 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
101 e) Pinned cannot go CSet, thus it never moves;
102 f) Humongous cannot be used for regular allocations;
103 g) Humongous cannot go CSet, thus it never moves;
104 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
105 follow associated humongous starts, not pinnable/movable by themselves);
106 i) Empty cannot go Trash, avoiding useless work;
107 j) ...
108 */
109
110 enum RegionState {
111 _empty_uncommitted, // region is empty and has memory uncommitted
112 _empty_committed, // region is empty and has memory committed
113 _regular, // region is for regular allocations
114 _humongous_start, // region is the humongous start
115 _humongous_cont, // region is the humongous continuation
116 _pinned_humongous_start, // region is both humongous start and pinned
117 _cset, // region is in collection set
118 _pinned, // region is pinned
119 _pinned_cset, // region is pinned and in cset (evac failure path)
120 _trash, // region contains only trash
121 _REGION_STATES_NUM // last
122 };
123
124 static const char* region_state_to_string(RegionState s) {
125 switch (s) {
126 case _empty_uncommitted: return "Empty Uncommitted";
127 case _empty_committed: return "Empty Committed";
128 case _regular: return "Regular";
129 case _humongous_start: return "Humongous Start";
130 case _humongous_cont: return "Humongous Continuation";
131 case _pinned_humongous_start: return "Humongous Start, Pinned";
132 case _cset: return "Collection Set";
133 case _pinned: return "Pinned";
134 case _pinned_cset: return "Collection Set, Pinned";
135 case _trash: return "Trash";
136 default:
137 ShouldNotReachHere();
138 return "";
139 }
140 }
141
142 // This method protects from accidental changes in enum order:
143 int region_state_to_ordinal(RegionState s) const {
144 switch (s) {
145 case _empty_uncommitted: return 0;
146 case _empty_committed: return 1;
147 case _regular: return 2;
148 case _humongous_start: return 3;
149 case _humongous_cont: return 4;
150 case _cset: return 5;
151 case _pinned: return 6;
152 case _trash: return 7;
153 case _pinned_cset: return 8;
154 case _pinned_humongous_start: return 9;
155 default:
156 ShouldNotReachHere();
157 return -1;
158 }
159 }
160
161 void report_illegal_transition(const char* method);
162
163 public:
164 static const int region_states_num() {
165 return _REGION_STATES_NUM;
166 }
167
168 // Allowed transitions from the outside code:
169 void make_regular_allocation();
170 void make_regular_bypass();
171 void make_humongous_start();
172 void make_humongous_cont();
173 void make_humongous_start_bypass();
174 void make_humongous_cont_bypass();
175 void make_pinned();
176 void make_unpinned();
177 void make_cset();
178 void make_trash();
179 void make_trash_immediate();
180 void make_empty();
181 void make_uncommitted();
182 void make_committed_bypass();
183
184 // Individual states:
185 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
186 bool is_empty_committed() const { return _state == _empty_committed; }
187 bool is_regular() const { return _state == _regular; }
188 bool is_humongous_continuation() const { return _state == _humongous_cont; }
189
190 // Participation in logical groups:
191 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
192 bool is_active() const { return !is_empty() && !is_trash(); }
193 bool is_trash() const { return _state == _trash; }
194 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
195 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
196 bool is_committed() const { return !is_empty_uncommitted(); }
197 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
198 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
199
200 // Macro-properties:
201 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
202 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
203
204 RegionState state() const { return _state; }
205 int state_ordinal() const { return region_state_to_ordinal(_state); }
206
207 void record_pin();
208 void record_unpin();
209 size_t pin_count() const;
210
211 private:
212 static size_t RegionCount;
213 static size_t RegionSizeBytes;
214 static size_t RegionSizeWords;
215 static size_t RegionSizeBytesShift;
216 static size_t RegionSizeWordsShift;
217 static size_t RegionSizeBytesMask;
218 static size_t RegionSizeWordsMask;
219 static size_t HumongousThresholdBytes;
220 static size_t HumongousThresholdWords;
221 static size_t MaxTLABSizeBytes;
222 static size_t MaxTLABSizeWords;
223
224 // Global allocation counter, increased for each allocation under Shenandoah heap lock.
225 // Padded to avoid false sharing with the read-only fields above.
226 struct PaddedAllocSeqNum {
227 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(uint64_t));
228 uint64_t value;
229 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
230
231 PaddedAllocSeqNum() {
232 // start with 1, reserve 0 for uninitialized value
233 value = 1;
234 }
235 };
236
237 static PaddedAllocSeqNum _alloc_seq_num;
238
239 // Never updated fields
240 ShenandoahHeap* _heap;
241 MemRegion _reserved;
242 size_t _region_number;
243
244 // Rarely updated fields
245 HeapWord* _new_top;
246 double _empty_time;
247
248 // Seldom updated fields
249 RegionState _state;
250
251 // Frequently updated fields
252 size_t _tlab_allocs;
253 size_t _gclab_allocs;
254 size_t _shared_allocs;
255
256 uint64_t _seqnum_first_alloc_mutator;
257 uint64_t _seqnum_first_alloc_gc;
258 uint64_t _seqnum_last_alloc_mutator;
259 uint64_t _seqnum_last_alloc_gc;
260
261 volatile size_t _live_data;
262 volatile size_t _critical_pins;
263
264 // Claim some space at the end to protect next region
265 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
266
267 public:
268 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
269
270 static const size_t MIN_NUM_REGIONS = 10;
271
272 static void setup_sizes(size_t max_heap_size);
273
274 double empty_time() {
275 return _empty_time;
276 }
277
278 inline static size_t required_regions(size_t bytes) {
279 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
280 }
281
282 inline static size_t region_count() {
283 return ShenandoahHeapRegion::RegionCount;
284 }
285
286 inline static size_t region_size_bytes() {
287 return ShenandoahHeapRegion::RegionSizeBytes;
288 }
289
290 inline static size_t region_size_words() {
291 return ShenandoahHeapRegion::RegionSizeWords;
292 }
293
294 inline static size_t region_size_bytes_shift() {
295 return ShenandoahHeapRegion::RegionSizeBytesShift;
296 }
297
298 inline static size_t region_size_words_shift() {
299 return ShenandoahHeapRegion::RegionSizeWordsShift;
300 }
301
302 inline static size_t region_size_bytes_mask() {
303 return ShenandoahHeapRegion::RegionSizeBytesMask;
304 }
305
306 inline static size_t region_size_words_mask() {
307 return ShenandoahHeapRegion::RegionSizeWordsMask;
308 }
309
310 // Convert to jint with sanity checking
311 inline static jint region_size_bytes_jint() {
312 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
313 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
314 }
315
316 // Convert to jint with sanity checking
317 inline static jint region_size_words_jint() {
318 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
319 return (jint)ShenandoahHeapRegion::RegionSizeWords;
320 }
321
322 // Convert to jint with sanity checking
323 inline static jint region_size_bytes_shift_jint() {
324 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
325 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
326 }
327
328 // Convert to jint with sanity checking
329 inline static jint region_size_words_shift_jint() {
330 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
331 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
332 }
333
334 inline static size_t humongous_threshold_bytes() {
335 return ShenandoahHeapRegion::HumongousThresholdBytes;
336 }
337
338 inline static size_t humongous_threshold_words() {
339 return ShenandoahHeapRegion::HumongousThresholdWords;
340 }
341
342 inline static size_t max_tlab_size_bytes() {
343 return ShenandoahHeapRegion::MaxTLABSizeBytes;
344 }
345
346 inline static size_t max_tlab_size_words() {
347 return ShenandoahHeapRegion::MaxTLABSizeWords;
348 }
349
350 static uint64_t seqnum_current_alloc() {
351 // Last used seq number
352 return _alloc_seq_num.value - 1;
353 }
354
355 size_t region_number() const;
356
357 // Allocation (return NULL if full)
358 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
359
360 HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL)
361
362 void clear_live_data();
363 void set_live_data(size_t s);
364
365 // Increase live data for newly allocated region
366 inline void increase_live_data_alloc_words(size_t s);
367
368 // Increase live data for region scanned with GC
369 inline void increase_live_data_gc_words(size_t s);
370
371 bool has_live() const;
372 size_t get_live_data_bytes() const;
373 size_t get_live_data_words() const;
374
375 void print_on(outputStream* st) const;
376
377 size_t garbage() const;
378
379 void recycle();
380
381 void oop_iterate(OopIterateClosure* cl);
382
383 HeapWord* block_start_const(const void* p) const;
384
385 bool in_collection_set() const;
386
387 // Find humongous start region that this region belongs to
388 ShenandoahHeapRegion* humongous_start_region() const;
389
390 CompactibleSpace* next_compaction_space() const shenandoah_not_implemented_return(NULL);
391 void prepare_for_compaction(CompactPoint* cp) shenandoah_not_implemented;
392 void adjust_pointers() shenandoah_not_implemented;
393 void compact() shenandoah_not_implemented;
394
395 void set_new_top(HeapWord* new_top) { _new_top = new_top; }
396 HeapWord* new_top() const { return _new_top; }
397
398 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
399 void reset_alloc_metadata_to_shared();
400 void reset_alloc_metadata();
401 size_t get_shared_allocs() const;
402 size_t get_tlab_allocs() const;
403 size_t get_gclab_allocs() const;
404
405 uint64_t seqnum_first_alloc() const {
406 if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc;
407 if (_seqnum_first_alloc_gc == 0) return _seqnum_first_alloc_mutator;
408 return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc);
409 }
410
411 uint64_t seqnum_last_alloc() const {
412 return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc);
413 }
414
415 uint64_t seqnum_first_alloc_mutator() const {
416 return _seqnum_first_alloc_mutator;
417 }
418
419 uint64_t seqnum_last_alloc_mutator() const {
420 return _seqnum_last_alloc_mutator;
421 }
422
423 uint64_t seqnum_first_alloc_gc() const {
424 return _seqnum_first_alloc_gc;
425 }
426
427 uint64_t seqnum_last_alloc_gc() const {
428 return _seqnum_last_alloc_gc;
429 }
430
431 private:
432 void do_commit();
433 void do_uncommit();
434
435 void oop_iterate_objects(OopIterateClosure* cl);
436 void oop_iterate_humongous(OopIterateClosure* cl);
437
438 inline void internal_increase_live_data(size_t s);
439
440 void set_state(RegionState to);
441 };
442
443 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP