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/shenandoahAgeCensus.hpp"
33 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
34 #include "gc/shenandoah/shenandoahAsserts.hpp"
35 #include "gc/shenandoah/shenandoahHeap.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 public:
129 static const char* region_state_to_string(RegionState s) {
130 switch (s) {
131 case _empty_uncommitted: return "Empty Uncommitted";
132 case _empty_committed: return "Empty Committed";
133 case _regular: return "Regular";
134 case _humongous_start: return "Humongous Start";
135 case _humongous_cont: return "Humongous Continuation";
136 case _pinned_humongous_start: return "Humongous Start, Pinned";
137 case _cset: return "Collection Set";
138 case _pinned: return "Pinned";
139 case _pinned_cset: return "Collection Set, Pinned";
140 case _trash: return "Trash";
141 default:
142 ShouldNotReachHere();
143 return "";
144 }
145 }
146
147 private:
148 // This method protects from accidental changes in enum order:
149 int region_state_to_ordinal(RegionState s) const {
150 switch (s) {
151 case _empty_uncommitted: return 0;
152 case _empty_committed: return 1;
153 case _regular: return 2;
154 case _humongous_start: return 3;
155 case _humongous_cont: return 4;
156 case _cset: return 5;
157 case _pinned: return 6;
158 case _trash: return 7;
159 case _pinned_cset: return 8;
160 case _pinned_humongous_start: return 9;
161 default:
162 ShouldNotReachHere();
163 return -1;
164 }
165 }
166
167 void report_illegal_transition(const char* method);
168
169 public:
170 static int region_states_num() {
171 return _REGION_STATES_NUM;
172 }
173
174 // Allowed transitions from the outside code:
175 void make_regular_allocation(ShenandoahAffiliation affiliation);
176 void make_affiliated_maybe();
177 void make_regular_bypass();
178 void make_humongous_start();
179 void make_humongous_cont();
180 void make_humongous_start_bypass(ShenandoahAffiliation affiliation);
181 void make_humongous_cont_bypass(ShenandoahAffiliation affiliation);
182 void make_pinned();
183 void make_unpinned();
184 void make_cset();
185 void make_trash();
186 void make_trash_immediate();
187 void make_empty();
188 void make_uncommitted();
189 void make_committed_bypass();
190
191 // Individual states:
192 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
193 bool is_empty_committed() const { return _state == _empty_committed; }
194 bool is_regular() const { return _state == _regular; }
195 bool is_humongous_continuation() const { return _state == _humongous_cont; }
196
197 // Participation in logical groups:
198 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
199 bool is_active() const { return !is_empty() && !is_trash(); }
200 bool is_trash() const { return _state == _trash; }
201 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
202 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
203 bool is_committed() const { return !is_empty_uncommitted(); }
204 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
205 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
206 bool is_regular_pinned() const { return _state == _pinned; }
207
208 inline bool is_young() const;
209 inline bool is_old() const;
210 inline bool is_affiliated() const;
211
212 // Macro-properties:
213 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
214 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
215
216 RegionState state() const { return _state; }
217 int state_ordinal() const { return region_state_to_ordinal(_state); }
218
219 void record_pin();
220 void record_unpin();
221 size_t pin_count() const;
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 volatile size_t _live_data;
259 volatile size_t _critical_pins;
260
261 HeapWord* volatile _update_watermark;
262
263 uint _age;
264 CENSUS_NOISE(uint _youth;) // tracks epochs of retrograde ageing (rejuvenation)
265
266 public:
267 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
268
269 static const size_t MIN_NUM_REGIONS = 10;
270
271 // Return adjusted max heap size
272 static size_t 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 inline size_t index() const {
351 return _index;
352 }
353
354 inline void save_top_before_promote();
355 inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
356 inline void restore_top_before_promote();
357 inline size_t garbage_before_padded_for_promote() const;
358
359 // If next available memory is not aligned on address that is multiple of alignment, fill the empty space
360 // so that returned object is aligned on an address that is a multiple of alignment_in_bytes. Requested
361 // size is in words. It is assumed that this->is_old(). A pad object is allocated, filled, and registered
362 // if necessary to assure the new allocation is properly aligned. Return nullptr if memory is not available.
363 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_bytes);
364
365 // Allocation (return nullptr if full)
366 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest req);
367
368 inline void clear_live_data();
369 void set_live_data(size_t s);
370
371 // Increase live data for newly allocated region
372 inline void increase_live_data_alloc_words(size_t s);
373
374 // Increase live data for region scanned with GC
375 inline void increase_live_data_gc_words(size_t s);
376
377 inline bool has_live() const;
378 inline size_t get_live_data_bytes() const;
379 inline size_t get_live_data_words() const;
380
381 inline size_t garbage() const;
382
383 void print_on(outputStream* st) const;
384
385 void recycle();
386
387 inline void begin_preemptible_coalesce_and_fill() {
388 _coalesce_and_fill_boundary = _bottom;
389 }
390
391 inline void end_preemptible_coalesce_and_fill() {
392 _coalesce_and_fill_boundary = _end;
393 }
394
395 inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
396 _coalesce_and_fill_boundary = next_focus;
397 }
398
399 inline HeapWord* resume_coalesce_and_fill() {
400 return _coalesce_and_fill_boundary;
401 }
402
403 // Coalesce contiguous spans of garbage objects by filling header and registering start locations with remembered set.
404 // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parsable. Old regions must be
405 // parsable because the mark bitmap is not reliable during the concurrent old mark.
406 // Return true iff region is completely coalesced and filled. Returns false if cancelled before task is complete.
407 bool oop_coalesce_and_fill(bool cancellable);
408
409 // Invoke closure on every reference contained within the humongous object that spans this humongous
410 // region if the reference is contained within a DIRTY card and the reference is no more than words following
411 // start within the humongous object.
412 void oop_iterate_humongous_slice_dirty(OopIterateClosure* cl, HeapWord* start, size_t words, bool write_table) const;
413
414 // Invoke closure on every reference contained within the humongous object starting from start and
415 // ending at start + words.
416 void oop_iterate_humongous_slice_all(OopIterateClosure* cl, HeapWord* start, size_t words) const;
417
418 HeapWord* block_start(const void* p) const;
419 size_t block_size(const HeapWord* p) const;
420 bool block_is_obj(const HeapWord* p) const { return p < top(); }
421
422 // Find humongous start region that this region belongs to
423 ShenandoahHeapRegion* humongous_start_region() const;
424
425 HeapWord* top() const { return _top; }
426 void set_top(HeapWord* v) { _top = v; }
427
428 HeapWord* new_top() const { return _new_top; }
429 void set_new_top(HeapWord* v) { _new_top = v; }
430
431 HeapWord* bottom() const { return _bottom; }
432 HeapWord* end() const { return _end; }
433
434 size_t capacity() const { return byte_size(bottom(), end()); }
435 size_t used() const { return byte_size(bottom(), top()); }
436 size_t used_before_promote() const { return byte_size(bottom(), get_top_before_promote()); }
437 size_t free() const { return byte_size(top(), end()); }
438
439 // Does this region contain this address?
440 bool contains(HeapWord* p) const {
441 return (bottom() <= p) && (p < top());
442 }
443
444 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
445 void reset_alloc_metadata();
446 size_t get_shared_allocs() const;
447 size_t get_tlab_allocs() const;
448 size_t get_gclab_allocs() const;
449 size_t get_plab_allocs() const;
450
451 inline HeapWord* get_update_watermark() const;
452 inline void set_update_watermark(HeapWord* w);
453 inline void set_update_watermark_at_safepoint(HeapWord* w);
454
455 inline ShenandoahAffiliation affiliation() const;
456 inline const char* affiliation_name() const;
457
458 void set_affiliation(ShenandoahAffiliation new_affiliation);
459
460 // Region ageing and rejuvenation
461 uint age() const { return _age; }
462 CENSUS_NOISE(uint youth() const { return _youth; })
463
464 void increment_age() {
465 const uint max_age = markWord::max_age;
466 assert(_age <= max_age, "Error");
467 if (_age++ >= max_age) {
468 _age = max_age; // clamp
469 }
470 }
471
472 void reset_age() {
473 CENSUS_NOISE(_youth += _age;)
474 _age = 0;
475 }
476
477 CENSUS_NOISE(void clear_youth() { _youth = 0; })
478
479 private:
480 void decrement_humongous_waste() const;
481 void do_commit();
482 void do_uncommit();
483
484 inline void internal_increase_live_data(size_t s);
485
486 void set_state(RegionState to);
487 };
488
489 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP