1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. 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.
18 *
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
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
27
28 #include "gc/shared/space.hpp"
29 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc/shenandoah/shenandoahAsserts.hpp"
31 #include "gc/shenandoah/shenandoahHeap.hpp"
32 #include "gc/shenandoah/shenandoahPacer.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 HeapWord* volatile _update_watermark;
265
266 // Claim some space at the end to protect next region
267 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
268
269 public:
270 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
271
272 static const size_t MIN_NUM_REGIONS = 10;
273
274 static void setup_sizes(size_t max_heap_size);
275
276 double empty_time() {
277 return _empty_time;
278 }
279
280 inline static size_t required_regions(size_t bytes) {
281 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
282 }
283
284 inline static size_t region_count() {
285 return ShenandoahHeapRegion::RegionCount;
286 }
287
288 inline static size_t region_size_bytes() {
289 return ShenandoahHeapRegion::RegionSizeBytes;
290 }
291
292 inline static size_t region_size_words() {
293 return ShenandoahHeapRegion::RegionSizeWords;
294 }
295
296 inline static size_t region_size_bytes_shift() {
297 return ShenandoahHeapRegion::RegionSizeBytesShift;
298 }
299
300 inline static size_t region_size_words_shift() {
301 return ShenandoahHeapRegion::RegionSizeWordsShift;
302 }
303
304 inline static size_t region_size_bytes_mask() {
305 return ShenandoahHeapRegion::RegionSizeBytesMask;
306 }
307
308 inline static size_t region_size_words_mask() {
309 return ShenandoahHeapRegion::RegionSizeWordsMask;
310 }
311
312 // Convert to jint with sanity checking
313 inline static jint region_size_bytes_jint() {
314 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
315 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
316 }
317
318 // Convert to jint with sanity checking
319 inline static jint region_size_words_jint() {
320 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
321 return (jint)ShenandoahHeapRegion::RegionSizeWords;
322 }
323
324 // Convert to jint with sanity checking
325 inline static jint region_size_bytes_shift_jint() {
326 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
327 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
328 }
329
330 // Convert to jint with sanity checking
331 inline static jint region_size_words_shift_jint() {
332 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
333 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
334 }
335
336 inline static size_t humongous_threshold_bytes() {
337 return ShenandoahHeapRegion::HumongousThresholdBytes;
338 }
339
340 inline static size_t humongous_threshold_words() {
341 return ShenandoahHeapRegion::HumongousThresholdWords;
342 }
343
344 inline static size_t max_tlab_size_bytes() {
345 return ShenandoahHeapRegion::MaxTLABSizeBytes;
346 }
347
348 inline static size_t max_tlab_size_words() {
349 return ShenandoahHeapRegion::MaxTLABSizeWords;
350 }
351
352 static uint64_t seqnum_current_alloc() {
353 // Last used seq number
354 return _alloc_seq_num.value - 1;
355 }
356
357 size_t region_number() const;
358
359 // Allocation (return NULL if full)
360 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
361
362 HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL)
363
364 void clear_live_data();
365 void set_live_data(size_t s);
366
367 // Increase live data for newly allocated region
368 inline void increase_live_data_alloc_words(size_t s);
369
370 // Increase live data for region scanned with GC
371 inline void increase_live_data_gc_words(size_t s);
372
373 bool has_live() const;
374 size_t get_live_data_bytes() const;
375 size_t get_live_data_words() const;
376
377 void print_on(outputStream* st) const;
378
379 size_t garbage() const;
380
381 void recycle();
382
383 void oop_iterate(OopIterateClosure* cl);
384
385 HeapWord* block_start_const(const void* p) const;
386
387 bool in_collection_set() const;
388
389 // Find humongous start region that this region belongs to
390 ShenandoahHeapRegion* humongous_start_region() const;
391
392 CompactibleSpace* next_compaction_space() const shenandoah_not_implemented_return(NULL);
393 void prepare_for_compaction(CompactPoint* cp) shenandoah_not_implemented;
394 void adjust_pointers() shenandoah_not_implemented;
395 void compact() shenandoah_not_implemented;
396
397 void set_new_top(HeapWord* new_top) { _new_top = new_top; }
398 HeapWord* new_top() const { return _new_top; }
399
400 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
401 void reset_alloc_metadata_to_shared();
402 void reset_alloc_metadata();
403 size_t get_shared_allocs() const;
404 size_t get_tlab_allocs() const;
405 size_t get_gclab_allocs() const;
406
407 uint64_t seqnum_first_alloc() const {
408 if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc;
409 if (_seqnum_first_alloc_gc == 0) return _seqnum_first_alloc_mutator;
410 return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc);
411 }
412
413 uint64_t seqnum_last_alloc() const {
414 return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc);
415 }
416
417 uint64_t seqnum_first_alloc_mutator() const {
418 return _seqnum_first_alloc_mutator;
419 }
420
421 uint64_t seqnum_last_alloc_mutator() const {
422 return _seqnum_last_alloc_mutator;
423 }
424
425 uint64_t seqnum_first_alloc_gc() const {
426 return _seqnum_first_alloc_gc;
427 }
428
429 uint64_t seqnum_last_alloc_gc() const {
430 return _seqnum_last_alloc_gc;
431 }
432
433 HeapWord* get_update_watermark() const {
434 assert(bottom() <= _update_watermark && _update_watermark <= top(), "within bounds");
435 return Atomic::load_acquire(&_update_watermark);
436 }
437
438 void set_update_watermark(HeapWord* w) {
439 assert(bottom() <= w && w <= top(), "within bounds");
440 Atomic::release_store(&_update_watermark, w);
441 }
442
443 private:
444 void do_commit();
445 void do_uncommit();
446
447 void oop_iterate_objects(OopIterateClosure* cl);
448 void oop_iterate_humongous(OopIterateClosure* cl);
449
450 inline void internal_increase_live_data(size_t s);
451
452 void set_state(RegionState to);
453 };
454
455 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP