1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
27 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
28
29 #include "gc/shared/gc_globals.hpp"
30 #include "gc/shared/spaceDecorator.hpp"
31 #include "gc/shenandoah/shenandoahAffiliation.hpp"
32 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
33 #include "gc/shenandoah/shenandoahAsserts.hpp"
34 #include "gc/shenandoah/shenandoahHeap.hpp"
35 #include "gc/shenandoah/shenandoahPacer.hpp"
36 #include "gc/shenandoah/shenandoahPadding.hpp"
37 #include "utilities/sizes.hpp"
38
39 class VMStructs;
40 class ShenandoahHeapRegionStateConstant;
41
42 class ShenandoahHeapRegion {
43 friend class VMStructs;
44 friend class ShenandoahHeapRegionStateConstant;
45 private:
46 /*
47 Region state is described by a state machine. Transitions are guarded by
48 heap lock, which allows changing the state of several regions atomically.
49 Region states can be logically aggregated in groups.
50
51 "Empty":
52 .................................................................
53 . .
54 . .
55 . Uncommitted <------- Committed <------------------------\
56 . | | . |
57 . \---------v-----------/ . |
58 . | . |
59 .........................|....................................... |
60 | |
61 "Active": | |
62 .........................|....................................... |
63 . | . |
64 . /-----------------^-------------------\ . |
65 . | | . |
66 . v v "Humongous": . |
67 . Regular ---\-----\ ..................O................ . |
68 . | ^ | | . | . . |
69 . | | | | . *---------\ . . |
70 . v | | | . v v . . |
71 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
72 . ^ / | | . Pinned v | . . |
73 . | / | | . *<--------/ . . |
74 . | v | | . | . . |
75 . CsetPinned | | ..................O................ . |
76 . | | | . |
77 . \-----\---v-------------------/ . |
78 . | . |
79 .........................|....................................... |
80 | |
81 "Trash": | |
82 .........................|....................................... |
83 . | . |
84 . v . |
85 . Trash ---------------------------------------/
86 . .
87 . .
88 .................................................................
89
90 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
91 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
92
93 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
94 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
95 quick reclamation without actual cleaning up.
96
97 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
98 Can be done asynchronously and in bulk.
99
100 Note how internal transitions disallow logic bugs:
101 a) No region can go Empty, unless properly reclaimed/recycled;
102 b) No region can go Uncommitted, unless reclaimed/recycled first;
103 c) Only Regular regions can go to CSet;
104 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
105 e) Pinned cannot go CSet, thus it never moves;
106 f) Humongous cannot be used for regular allocations;
107 g) Humongous cannot go CSet, thus it never moves;
108 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
109 follow associated humongous starts, not pinnable/movable by themselves);
110 i) Empty cannot go Trash, avoiding useless work;
111 j) ...
112 */
113
114 enum RegionState {
115 _empty_uncommitted, // region is empty and has memory uncommitted
116 _empty_committed, // region is empty and has memory committed
117 _regular, // region is for regular allocations
118 _humongous_start, // region is the humongous start
119 _humongous_cont, // region is the humongous continuation
120 _pinned_humongous_start, // region is both humongous start and pinned
121 _cset, // region is in collection set
122 _pinned, // region is pinned
123 _pinned_cset, // region is pinned and in cset (evac failure path)
124 _trash, // region contains only trash
125 _REGION_STATES_NUM // last
126 };
127
128 static const char* region_state_to_string(RegionState s) {
129 switch (s) {
130 case _empty_uncommitted: return "Empty Uncommitted";
131 case _empty_committed: return "Empty Committed";
132 case _regular: return "Regular";
133 case _humongous_start: return "Humongous Start";
134 case _humongous_cont: return "Humongous Continuation";
135 case _pinned_humongous_start: return "Humongous Start, Pinned";
136 case _cset: return "Collection Set";
137 case _pinned: return "Pinned";
138 case _pinned_cset: return "Collection Set, Pinned";
139 case _trash: return "Trash";
140 default:
141 ShouldNotReachHere();
142 return "";
143 }
144 }
145
146 // This method protects from accidental changes in enum order:
147 int region_state_to_ordinal(RegionState s) const {
148 switch (s) {
149 case _empty_uncommitted: return 0;
150 case _empty_committed: return 1;
151 case _regular: return 2;
152 case _humongous_start: return 3;
153 case _humongous_cont: return 4;
154 case _cset: return 5;
155 case _pinned: return 6;
156 case _trash: return 7;
157 case _pinned_cset: return 8;
158 case _pinned_humongous_start: return 9;
159 default:
160 ShouldNotReachHere();
161 return -1;
162 }
163 }
164
165 void report_illegal_transition(const char* method);
166
167 public:
168 static int region_states_num() {
169 return _REGION_STATES_NUM;
170 }
171
172 // Allowed transitions from the outside code:
173 void make_regular_allocation(ShenandoahAffiliation affiliation);
174 void make_young_maybe();
175 void make_regular_bypass();
176 void make_humongous_start();
177 void make_humongous_cont();
178 void make_humongous_start_bypass(ShenandoahAffiliation affiliation);
179 void make_humongous_cont_bypass(ShenandoahAffiliation affiliation);
180 void make_pinned();
181 void make_unpinned();
182 void make_cset();
183 void make_trash();
184 void make_trash_immediate();
185 void make_empty();
186 void make_uncommitted();
187 void make_committed_bypass();
188
189 // Individual states:
190 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
191 bool is_empty_committed() const { return _state == _empty_committed; }
192 bool is_regular() const { return _state == _regular; }
193 bool is_humongous_continuation() const { return _state == _humongous_cont; }
194
195 // Participation in logical groups:
196 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
197 bool is_active() const { return !is_empty() && !is_trash(); }
198 bool is_trash() const { return _state == _trash; }
199 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
200 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
201 bool is_committed() const { return !is_empty_uncommitted(); }
202 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
203 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
204 inline bool is_young() const;
205 inline bool is_old() const;
206 inline bool is_affiliated() const;
207
208 // Macro-properties:
209 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
210 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
211
212 RegionState state() const { return _state; }
213 int state_ordinal() const { return region_state_to_ordinal(_state); }
214
215 void record_pin();
216 void record_unpin();
217 size_t pin_count() const;
218
219 void clear_young_lab_flags();
220 void set_young_lab_flag();
221 bool has_young_lab_flag();
222
223 private:
224 static size_t RegionCount;
225 static size_t RegionSizeBytes;
226 static size_t RegionSizeWords;
227 static size_t RegionSizeBytesShift;
228 static size_t RegionSizeWordsShift;
229 static size_t RegionSizeBytesMask;
230 static size_t RegionSizeWordsMask;
231 static size_t HumongousThresholdBytes;
232 static size_t HumongousThresholdWords;
233 static size_t MaxTLABSizeBytes;
234 static size_t MaxTLABSizeWords;
235
236 // Never updated fields
237 size_t const _index;
238 HeapWord* const _bottom;
239 HeapWord* const _end;
240
241 // Rarely updated fields
242 HeapWord* _new_top;
243 double _empty_time;
244
245 HeapWord* _top_before_promoted;
246
247 // Seldom updated fields
248 RegionState _state;
249 HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
250
251 // Frequently updated fields
252 HeapWord* _top;
253
254 size_t _tlab_allocs;
255 size_t _gclab_allocs;
256 size_t _plab_allocs;
257
258 bool _has_young_lab;
259
260 volatile size_t _live_data;
261 volatile size_t _critical_pins;
262
263 HeapWord* volatile _update_watermark;
264
265 uint _age;
266 CENSUS_NOISE(uint _youth;) // tracks epochs of retrograde ageing (rejuvenation)
267
268 public:
269 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
270
271 static const size_t MIN_NUM_REGIONS = 10;
272
273 // Return adjusted max heap size
274 static size_t 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 inline size_t index() const {
353 return _index;
354 }
355
356 inline void save_top_before_promote();
357 inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
358 inline void restore_top_before_promote();
359 inline size_t garbage_before_padded_for_promote() const;
360
361 // Allocation (return nullptr if full)
362 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_words);
363
364 // Allocation (return nullptr if full)
365 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest req);
366
367 inline void clear_live_data();
368 void set_live_data(size_t s);
369
370 // Increase live data for newly allocated region
371 inline void increase_live_data_alloc_words(size_t s);
372
373 // Increase live data for region scanned with GC
374 inline void increase_live_data_gc_words(size_t s);
375
376 inline bool has_live() const;
377 inline size_t get_live_data_bytes() const;
378 inline size_t get_live_data_words() const;
379
380 inline size_t garbage() const;
381
382 void print_on(outputStream* st) const;
383
384 void recycle();
385
386 inline void begin_preemptible_coalesce_and_fill() {
387 _coalesce_and_fill_boundary = _bottom;
388 }
389
390 inline void end_preemptible_coalesce_and_fill() {
391 _coalesce_and_fill_boundary = _end;
392 }
393
394 inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
395 _coalesce_and_fill_boundary = next_focus;
396 }
397
398 inline HeapWord* resume_coalesce_and_fill() {
399 return _coalesce_and_fill_boundary;
400 }
401
402 // Coalesce contiguous spans of garbage objects by filling header and reregistering start locations with remembered set.
403 // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parseable. Return true iff
404 // region is completely coalesced and filled. Returns false if cancelled before task is complete.
405 bool oop_fill_and_coalesce();
406
407 // Like oop_fill_and_coalesce(), but without honoring cancellation requests.
408 bool oop_fill_and_coalesce_without_cancel();
409
410 // During global collections, this service iterates through an old-gen heap region that is not part of collection
411 // set to fill and register ranges of dead memory. Note that live objects were previously registered. Some dead objects
412 // that are subsumed into coalesced ranges of dead memory need to be "unregistered".
413 void global_oop_iterate_and_fill_dead(OopIterateClosure* cl);
414 void oop_iterate_humongous(OopIterateClosure* cl);
415 void oop_iterate_humongous(OopIterateClosure* cl, HeapWord* start, size_t words);
416
417 // Invoke closure on every reference contained within the humongous object that spans this humongous
418 // region if the reference is contained within a DIRTY card and the reference is no more than words following
419 // start within the humongous object.
420 void oop_iterate_humongous_slice(OopIterateClosure* cl, bool dirty_only, HeapWord* start, size_t words, bool write_table);
421
422 HeapWord* block_start(const void* p) const;
423 size_t block_size(const HeapWord* p) const;
424 bool block_is_obj(const HeapWord* p) const { return p < top(); }
425
426 // Find humongous start region that this region belongs to
427 ShenandoahHeapRegion* humongous_start_region() const;
428
429 HeapWord* top() const { return _top; }
430 void set_top(HeapWord* v) { _top = v; }
431
432 HeapWord* new_top() const { return _new_top; }
433 void set_new_top(HeapWord* v) { _new_top = v; }
434
435 HeapWord* bottom() const { return _bottom; }
436 HeapWord* end() const { return _end; }
437
438 size_t capacity() const { return byte_size(bottom(), end()); }
439 size_t used() const { return byte_size(bottom(), top()); }
440 size_t used_before_promote() const { return byte_size(bottom(), get_top_before_promote()); }
441 size_t free() const { return byte_size(top(), end()); }
442
443 // Does this region contain this address?
444 bool contains(HeapWord* p) const {
445 return (bottom() <= p) && (p < top());
446 }
447
448 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
449 void reset_alloc_metadata();
450 size_t get_shared_allocs() const;
451 size_t get_tlab_allocs() const;
452 size_t get_gclab_allocs() const;
453 size_t get_plab_allocs() const;
454
455 inline HeapWord* get_update_watermark() const;
456 inline void set_update_watermark(HeapWord* w);
457 inline void set_update_watermark_at_safepoint(HeapWord* w);
458
459 inline ShenandoahAffiliation affiliation() const;
460 inline const char* affiliation_name() const;
461
462 void set_affiliation(ShenandoahAffiliation new_affiliation);
463
464 // Region ageing and rejuvenation
465 uint age() { return _age; }
466 CENSUS_NOISE(uint youth() { return _youth; })
467
468 void increment_age() {
469 const uint max_age = markWord::max_age;
470 assert(_age <= max_age, "Error");
471 if (_age++ >= max_age) {
472 _age = max_age; // clamp
473 }
474 }
475
476 void reset_age() {
477 CENSUS_NOISE(_youth += _age;)
478 _age = 0;
479 }
480
481 CENSUS_NOISE(void clear_youth() { _youth = 0; })
482
483 // Register all objects. Set all remembered set cards to dirty.
484 void promote_humongous();
485 void promote_in_place();
486
487 private:
488 void decrement_humongous_waste() const;
489 void do_commit();
490 void do_uncommit();
491
492 // This is an old-region that was not part of the collection set during a GLOBAL collection. We coalesce the dead
493 // objects, but do not need to register the live objects as they are already registered.
494 void global_oop_iterate_objects_and_fill_dead(OopIterateClosure* cl);
495
496 inline void internal_increase_live_data(size_t s);
497
498 void set_state(RegionState to);
499 };
500
501 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP