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 void recycle_internal();
169
170 public:
171 static int region_states_num() {
172 return _REGION_STATES_NUM;
173 }
174
175 // Allowed transitions from the outside code:
176 void make_regular_allocation(ShenandoahAffiliation affiliation);
177 void make_affiliated_maybe();
178 void make_regular_bypass();
179 void make_humongous_start();
180 void make_humongous_cont();
181 void make_humongous_start_bypass(ShenandoahAffiliation affiliation);
182 void make_humongous_cont_bypass(ShenandoahAffiliation affiliation);
183 void make_pinned();
184 void make_unpinned();
185 void make_cset();
186 void make_trash();
187 void make_trash_immediate();
188 void make_empty();
189 void make_uncommitted();
190 void make_committed_bypass();
191
192 // Primitive state predicates
193 bool is_empty_uncommitted() const { return state() == _empty_uncommitted; }
194 bool is_empty_committed() const { return state() == _empty_committed; }
195 bool is_regular() const { return state() == _regular; }
196 bool is_humongous_continuation() const { return state() == _humongous_cont; }
197 bool is_regular_pinned() const { return state() == _pinned; }
198 bool is_trash() const { return state() == _trash; }
199
200 // Derived state predicates (boolean combinations of individual states)
201 bool static is_empty_state(RegionState state) { return state == _empty_committed || state == _empty_uncommitted; }
202 bool static is_humongous_start_state(RegionState state) { return state == _humongous_start || state == _pinned_humongous_start; }
203 bool is_empty() const { return is_empty_state(this->state()); }
204 bool is_active() const { auto cur_state = state(); return !is_empty_state(cur_state) && cur_state != _trash; }
205 bool is_humongous_start() const { return is_humongous_start_state(state()); }
206 bool is_humongous() const { auto cur_state = state(); return is_humongous_start_state(cur_state) || cur_state == _humongous_cont; }
207 bool is_committed() const { return !is_empty_uncommitted(); }
208 bool is_cset() const { auto cur_state = state(); return cur_state == _cset || cur_state == _pinned_cset; }
209 bool is_pinned() const { auto cur_state = state(); return cur_state == _pinned || cur_state == _pinned_cset || cur_state == _pinned_humongous_start; }
210
211 inline bool is_young() const;
212 inline bool is_old() const;
213 inline bool is_affiliated() const;
214
215 // Macro-properties:
216 bool is_alloc_allowed() const { auto cur_state = state(); return is_empty_state(cur_state) || cur_state == _regular || cur_state == _pinned; }
217 bool is_stw_move_allowed() const { auto cur_state = state(); return cur_state == _regular || cur_state == _cset || (ShenandoahHumongousMoves && cur_state == _humongous_start); }
218
219 RegionState state() const { return Atomic::load(&_state); }
220 int state_ordinal() const { return region_state_to_ordinal(state()); }
221
222 void record_pin();
223 void record_unpin();
224 size_t pin_count() const;
225
226 private:
227 static size_t RegionCount;
228 static size_t RegionSizeBytes;
229 static size_t RegionSizeWords;
230 static size_t RegionSizeBytesShift;
231 static size_t RegionSizeWordsShift;
232 static size_t RegionSizeBytesMask;
233 static size_t RegionSizeWordsMask;
234 static size_t MaxTLABSizeBytes;
235 static size_t MaxTLABSizeWords;
236
237 // Never updated fields
238 size_t const _index;
239 HeapWord* const _bottom;
240 HeapWord* const _end;
241
242 // Rarely updated fields
243 HeapWord* _new_top;
244 double _empty_time;
245
246 HeapWord* _top_before_promoted;
247
248 // Seldom updated fields
249 volatile RegionState _state;
250 HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
251
252 // Frequently updated fields
253 HeapWord* _top;
254
255 size_t _tlab_allocs;
256 size_t _gclab_allocs;
257 size_t _plab_allocs;
258
259 volatile size_t _live_data;
260 volatile size_t _critical_pins;
261
262 HeapWord* volatile _update_watermark;
263
264 uint _age;
265 CENSUS_NOISE(uint _youth;) // tracks epochs of retrograde ageing (rejuvenation)
266
267 ShenandoahSharedFlag _recycling; // Used to indicate that the region is being recycled; see try_recycle*().
268
269 bool _needs_bitmap_reset;
270
271 public:
272 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
273
274 static const size_t MIN_NUM_REGIONS = 10;
275
276 // Return adjusted max heap size
277 static size_t setup_sizes(size_t max_heap_size);
278
279 double empty_time() {
280 return _empty_time;
281 }
282
283 inline static size_t required_regions(size_t bytes) {
284 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
285 }
286
287 inline static bool requires_humongous(size_t words) {
288 return words > ShenandoahHeapRegion::RegionSizeWords;
289 }
290
291 inline static size_t region_count() {
292 return ShenandoahHeapRegion::RegionCount;
293 }
294
295 inline static size_t region_size_bytes() {
296 return ShenandoahHeapRegion::RegionSizeBytes;
297 }
298
299 inline static size_t region_size_words() {
300 return ShenandoahHeapRegion::RegionSizeWords;
301 }
302
303 inline static size_t region_size_bytes_shift() {
304 return ShenandoahHeapRegion::RegionSizeBytesShift;
305 }
306
307 inline static size_t region_size_words_shift() {
308 return ShenandoahHeapRegion::RegionSizeWordsShift;
309 }
310
311 inline static size_t region_size_bytes_mask() {
312 return ShenandoahHeapRegion::RegionSizeBytesMask;
313 }
314
315 inline static size_t region_size_words_mask() {
316 return ShenandoahHeapRegion::RegionSizeWordsMask;
317 }
318
319 // Convert to jint with sanity checking
320 inline static jint region_size_bytes_jint() {
321 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
322 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
323 }
324
325 // Convert to jint with sanity checking
326 inline static jint region_size_words_jint() {
327 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
328 return (jint)ShenandoahHeapRegion::RegionSizeWords;
329 }
330
331 // Convert to jint with sanity checking
332 inline static jint region_size_bytes_shift_jint() {
333 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
334 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
335 }
336
337 // Convert to jint with sanity checking
338 inline static jint region_size_words_shift_jint() {
339 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
340 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
341 }
342
343 inline static size_t max_tlab_size_bytes() {
344 return ShenandoahHeapRegion::MaxTLABSizeBytes;
345 }
346
347 inline static size_t max_tlab_size_words() {
348 return ShenandoahHeapRegion::MaxTLABSizeWords;
349 }
350
351 inline size_t index() const {
352 return _index;
353 }
354
355 inline void save_top_before_promote();
356 inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
357 inline void restore_top_before_promote();
358 inline size_t garbage_before_padded_for_promote() const;
359
360 // If next available memory is not aligned on address that is multiple of alignment, fill the empty space
361 // so that returned object is aligned on an address that is a multiple of alignment_in_bytes. Requested
362 // size is in words. It is assumed that this->is_old(). A pad object is allocated, filled, and registered
363 // if necessary to assure the new allocation is properly aligned. Return nullptr if memory is not available.
364 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_bytes);
365
366 // Allocation (return nullptr if full)
367 inline HeapWord* allocate(size_t word_size, const ShenandoahAllocRequest& req);
368
369 inline void clear_live_data();
370 void set_live_data(size_t s);
371
372 // Increase live data for newly allocated region
373 inline void increase_live_data_alloc_words(size_t s);
374
375 // Increase live data for region scanned with GC
376 inline void increase_live_data_gc_words(size_t s);
377
378 inline bool has_live() const;
379 inline size_t get_live_data_bytes() const;
380 inline size_t get_live_data_words() const;
381
382 inline size_t garbage() const;
383
384 void print_on(outputStream* st) const;
385
386 void try_recycle_under_lock();
387
388 void try_recycle();
389
390 inline void begin_preemptible_coalesce_and_fill() {
391 _coalesce_and_fill_boundary = _bottom;
392 }
393
394 inline void end_preemptible_coalesce_and_fill() {
395 _coalesce_and_fill_boundary = _end;
396 }
397
398 inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
399 _coalesce_and_fill_boundary = next_focus;
400 }
401
402 inline HeapWord* resume_coalesce_and_fill() {
403 return _coalesce_and_fill_boundary;
404 }
405
406 // Coalesce contiguous spans of garbage objects by filling header and registering start locations with remembered set.
407 // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parsable. Old regions must be
408 // parsable because the mark bitmap is not reliable during the concurrent old mark.
409 // Return true iff region is completely coalesced and filled. Returns false if cancelled before task is complete.
410 bool oop_coalesce_and_fill(bool cancellable);
411
412 // Invoke closure on every reference contained within the humongous object that spans this humongous
413 // region if the reference is contained within a DIRTY card and the reference is no more than words following
414 // start within the humongous object.
415 void oop_iterate_humongous_slice_dirty(OopIterateClosure* cl, HeapWord* start, size_t words, bool write_table) const;
416
417 // Invoke closure on every reference contained within the humongous object starting from start and
418 // ending at start + words.
419 void oop_iterate_humongous_slice_all(OopIterateClosure* cl, HeapWord* start, size_t words) const;
420
421 HeapWord* block_start(const void* p) const;
422 size_t block_size(const HeapWord* p) const;
423 bool block_is_obj(const HeapWord* p) const { return p < top(); }
424
425 // Find humongous start region that this region belongs to
426 ShenandoahHeapRegion* humongous_start_region() const;
427
428 HeapWord* top() const { return _top; }
429 void set_top(HeapWord* v) { _top = v; }
430
431 HeapWord* new_top() const { return _new_top; }
432 void set_new_top(HeapWord* v) { _new_top = v; }
433
434 HeapWord* bottom() const { return _bottom; }
435 HeapWord* end() const { return _end; }
436
437 size_t capacity() const { return byte_size(bottom(), end()); }
438 size_t used() const { return byte_size(bottom(), top()); }
439 size_t used_before_promote() const { return byte_size(bottom(), get_top_before_promote()); }
440 size_t free() const { return byte_size(top(), end()); }
441
442 // Does this region contain this address?
443 bool contains(HeapWord* p) const {
444 return (bottom() <= p) && (p < top());
445 }
446
447 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
448 void reset_alloc_metadata();
449 size_t get_shared_allocs() const;
450 size_t get_tlab_allocs() const;
451 size_t get_gclab_allocs() const;
452 size_t get_plab_allocs() const;
453
454 inline HeapWord* get_update_watermark() const;
455 inline void set_update_watermark(HeapWord* w);
456 inline void set_update_watermark_at_safepoint(HeapWord* w);
457
458 inline ShenandoahAffiliation affiliation() const;
459 inline const char* affiliation_name() const;
460
461 void set_affiliation(ShenandoahAffiliation new_affiliation);
462
463 // Region ageing and rejuvenation
464 uint age() const { return _age; }
465 CENSUS_NOISE(uint youth() const { return _youth; })
466
467 void increment_age() {
468 const uint max_age = markWord::max_age;
469 assert(_age <= max_age, "Error");
470 if (_age++ >= max_age) {
471 _age = max_age; // clamp
472 }
473 }
474
475 void reset_age() {
476 CENSUS_NOISE(_youth += _age;)
477 _age = 0;
478 }
479
480 CENSUS_NOISE(void clear_youth() { _youth = 0; })
481
482 inline bool need_bitmap_reset() const {
483 return _needs_bitmap_reset;
484 }
485
486 inline void set_needs_bitmap_reset() {
487 _needs_bitmap_reset = true;
488 }
489
490 inline void unset_needs_bitmap_reset() {
491 _needs_bitmap_reset = false;
492 }
493
494 private:
495 void decrement_humongous_waste() const;
496 void do_commit();
497 void do_uncommit();
498
499 inline void internal_increase_live_data(size_t s);
500
501 void set_state(RegionState to);
502 };
503
504 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP