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