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/shenandoahPadding.hpp"
36 #include "utilities/sizes.hpp"
37
38 class VMStructs;
39 class ShenandoahHeapRegionStateConstant;
40
41 class ShenandoahHeapRegion {
42 friend class VMStructs;
43 friend class ShenandoahHeapRegionStateConstant;
44 private:
45 /*
46 Region state is described by a state machine. Transitions are guarded by
47 heap lock, which allows changing the state of several regions atomically.
48 Region states can be logically aggregated in groups.
49
50 "Empty":
51 .................................................................
52 . .
53 . .
54 . Uncommitted <------- Committed <------------------------\
55 . | | . |
56 . \---------v-----------/ . |
57 . | . |
58 .........................|....................................... |
59 | |
60 "Active": | |
61 .........................|....................................... |
62 . | . |
63 . /-----------------^-------------------\ . |
64 . | | . |
65 . v v "Humongous": . |
66 . Regular ---\-----\ ..................O................ . |
67 . | ^ | | . | . . |
68 . | | | | . *---------\ . . |
69 . v | | | . v v . . |
70 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
71 . ^ / | | . Pinned v | . . |
72 . | / | | . *<--------/ . . |
73 . | v | | . | . . |
74 . CsetPinned | | ..................O................ . |
75 . | | | . |
76 . \-----\---v-------------------/ . |
77 . | . |
78 .........................|....................................... |
79 | |
80 "Trash": | |
81 .........................|....................................... |
82 . | . |
83 . v . |
84 . Trash ---------------------------------------/
85 . .
86 . .
87 .................................................................
88
89 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
90 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
91
92 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
93 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
94 quick reclamation without actual cleaning up.
95
96 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
97 Can be done asynchronously and in bulk.
98
99 Note how internal transitions disallow logic bugs:
100 a) No region can go Empty, unless properly reclaimed/recycled;
101 b) No region can go Uncommitted, unless reclaimed/recycled first;
102 c) Only Regular regions can go to CSet;
103 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
104 e) Pinned cannot go CSet, thus it never moves;
105 f) Humongous cannot be used for regular allocations;
106 g) Humongous cannot go CSet, thus it never moves;
107 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
108 follow associated humongous starts, not pinnable/movable by themselves);
109 i) Empty cannot go Trash, avoiding useless work;
110 j) ...
111 */
112
113 enum RegionState {
114 _empty_uncommitted, // region is empty and has memory uncommitted
115 _empty_committed, // region is empty and has memory committed
116 _regular, // region is for regular allocations
117 _humongous_start, // region is the humongous start
118 _humongous_cont, // region is the humongous continuation
119 _pinned_humongous_start, // region is both humongous start and pinned
120 _cset, // region is in collection set
121 _pinned, // region is pinned
122 _pinned_cset, // region is pinned and in cset (evac failure path)
123 _trash, // region contains only trash
124 _REGION_STATES_NUM // last
125 };
126
127 public:
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 private:
147 // This method protects from accidental changes in enum order:
148 int region_state_to_ordinal(RegionState s) const {
149 switch (s) {
150 case _empty_uncommitted: return 0;
151 case _empty_committed: return 1;
152 case _regular: return 2;
153 case _humongous_start: return 3;
154 case _humongous_cont: return 4;
155 case _cset: return 5;
156 case _pinned: return 6;
157 case _trash: return 7;
158 case _pinned_cset: return 8;
159 case _pinned_humongous_start: return 9;
160 default:
161 ShouldNotReachHere();
162 return -1;
163 }
164 }
165
166 void report_illegal_transition(const char* method);
167
168 public:
169 static int region_states_num() {
170 return _REGION_STATES_NUM;
171 }
172
173 // Allowed transitions from the outside code:
174 void make_regular_allocation(ShenandoahAffiliation affiliation);
175 void make_young_maybe();
176 void make_regular_bypass();
177 void make_humongous_start();
178 void make_humongous_cont();
179 void make_humongous_start_bypass(ShenandoahAffiliation affiliation);
180 void make_humongous_cont_bypass(ShenandoahAffiliation affiliation);
181 void make_pinned();
182 void make_unpinned();
183 void make_cset();
184 void make_trash();
185 void make_trash_immediate();
186 void make_empty();
187 void make_uncommitted();
188 void make_committed_bypass();
189
190 // Individual states:
191 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
192 bool is_empty_committed() const { return _state == _empty_committed; }
193 bool is_regular() const { return _state == _regular; }
194 bool is_humongous_continuation() const { return _state == _humongous_cont; }
195
196 // Participation in logical groups:
197 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
198 bool is_active() const { return !is_empty() && !is_trash(); }
199 bool is_trash() const { return _state == _trash; }
200 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
201 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
202 bool is_committed() const { return !is_empty_uncommitted(); }
203 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
204 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
205 bool is_regular_pinned() const { return _state == _pinned; }
206
207 inline bool is_young() const;
208 inline bool is_old() const;
209 inline bool is_affiliated() const;
210
211 // Macro-properties:
212 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
213 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
214
215 RegionState state() const { return _state; }
216 int state_ordinal() const { return region_state_to_ordinal(_state); }
217
218 void record_pin();
219 void record_unpin();
220 size_t pin_count() const;
221
222 private:
223 static size_t RegionCount;
224 static size_t RegionSizeBytes;
225 static size_t RegionSizeWords;
226 static size_t RegionSizeBytesShift;
227 static size_t RegionSizeWordsShift;
228 static size_t RegionSizeBytesMask;
229 static size_t RegionSizeWordsMask;
230 static size_t HumongousThresholdBytes;
231 static size_t HumongousThresholdWords;
232 static size_t MaxTLABSizeBytes;
233 static size_t MaxTLABSizeWords;
234
235 // Never updated fields
236 size_t const _index;
237 HeapWord* const _bottom;
238 HeapWord* const _end;
239
240 // Rarely updated fields
241 HeapWord* _new_top;
242 double _empty_time;
243
244 HeapWord* _top_before_promoted;
245
246 // Seldom updated fields
247 RegionState _state;
248 HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
249
250 // Frequently updated fields
251 HeapWord* _top;
252
253 size_t _tlab_allocs;
254 size_t _gclab_allocs;
255 size_t _plab_allocs;
256
257 volatile size_t _live_data;
258 volatile size_t _critical_pins;
259
260 HeapWord* volatile _update_watermark;
261
262 uint _age;
263 CENSUS_NOISE(uint _youth;) // tracks epochs of retrograde ageing (rejuvenation)
264
265 public:
266 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
267
268 static const size_t MIN_NUM_REGIONS = 10;
269
270 // Return adjusted max heap size
271 static size_t setup_sizes(size_t max_heap_size);
272
273 double empty_time() {
274 return _empty_time;
275 }
276
277 inline static size_t required_regions(size_t bytes) {
278 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
279 }
280
281 inline static size_t region_count() {
282 return ShenandoahHeapRegion::RegionCount;
283 }
284
285 inline static size_t region_size_bytes() {
286 return ShenandoahHeapRegion::RegionSizeBytes;
287 }
288
289 inline static size_t region_size_words() {
290 return ShenandoahHeapRegion::RegionSizeWords;
291 }
292
293 inline static size_t region_size_bytes_shift() {
294 return ShenandoahHeapRegion::RegionSizeBytesShift;
295 }
296
297 inline static size_t region_size_words_shift() {
298 return ShenandoahHeapRegion::RegionSizeWordsShift;
299 }
300
301 inline static size_t region_size_bytes_mask() {
302 return ShenandoahHeapRegion::RegionSizeBytesMask;
303 }
304
305 inline static size_t region_size_words_mask() {
306 return ShenandoahHeapRegion::RegionSizeWordsMask;
307 }
308
309 // Convert to jint with sanity checking
310 inline static jint region_size_bytes_jint() {
311 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
312 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
313 }
314
315 // Convert to jint with sanity checking
316 inline static jint region_size_words_jint() {
317 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
318 return (jint)ShenandoahHeapRegion::RegionSizeWords;
319 }
320
321 // Convert to jint with sanity checking
322 inline static jint region_size_bytes_shift_jint() {
323 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
324 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
325 }
326
327 // Convert to jint with sanity checking
328 inline static jint region_size_words_shift_jint() {
329 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
330 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
331 }
332
333 inline static size_t humongous_threshold_bytes() {
334 return ShenandoahHeapRegion::HumongousThresholdBytes;
335 }
336
337 inline static size_t humongous_threshold_words() {
338 return ShenandoahHeapRegion::HumongousThresholdWords;
339 }
340
341 inline static size_t max_tlab_size_bytes() {
342 return ShenandoahHeapRegion::MaxTLABSizeBytes;
343 }
344
345 inline static size_t max_tlab_size_words() {
346 return ShenandoahHeapRegion::MaxTLABSizeWords;
347 }
348
349 inline size_t index() const {
350 return _index;
351 }
352
353 inline void save_top_before_promote();
354 inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
355 inline void restore_top_before_promote();
356 inline size_t garbage_before_padded_for_promote() const;
357
358 // If next available memory is not aligned on address that is multiple of alignment, fill the empty space
359 // so that returned object is aligned on an address that is a multiple of alignment_in_bytes. Requested
360 // size is in words. It is assumed that this->is_old(). A pad object is allocated, filled, and registered
361 // if necessary to assure the new allocation is properly aligned. Return nullptr if memory is not available.
362 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_bytes);
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 parsable. Return true iff
404 // region is completely coalesced and filled. Returns false if cancelled before task is complete.
405 bool oop_coalesce_and_fill(bool cancellable);
406
407 // Invoke closure on every reference contained within the humongous object that spans this humongous
408 // region if the reference is contained within a DIRTY card and the reference is no more than words following
409 // start within the humongous object.
410 void oop_iterate_humongous_slice(OopIterateClosure* cl, bool dirty_only, HeapWord* start, size_t words, bool write_table);
411
412 HeapWord* block_start(const void* p) const;
413 size_t block_size(const HeapWord* p) const;
414 bool block_is_obj(const HeapWord* p) const { return p < top(); }
415
416 // Find humongous start region that this region belongs to
417 ShenandoahHeapRegion* humongous_start_region() const;
418
419 HeapWord* top() const { return _top; }
420 void set_top(HeapWord* v) { _top = v; }
421
422 HeapWord* new_top() const { return _new_top; }
423 void set_new_top(HeapWord* v) { _new_top = v; }
424
425 HeapWord* bottom() const { return _bottom; }
426 HeapWord* end() const { return _end; }
427
428 size_t capacity() const { return byte_size(bottom(), end()); }
429 size_t used() const { return byte_size(bottom(), top()); }
430 size_t used_before_promote() const { return byte_size(bottom(), get_top_before_promote()); }
431 size_t free() const { return byte_size(top(), end()); }
432
433 // Does this region contain this address?
434 bool contains(HeapWord* p) const {
435 return (bottom() <= p) && (p < top());
436 }
437
438 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
439 void reset_alloc_metadata();
440 size_t get_shared_allocs() const;
441 size_t get_tlab_allocs() const;
442 size_t get_gclab_allocs() const;
443 size_t get_plab_allocs() const;
444
445 inline HeapWord* get_update_watermark() const;
446 inline void set_update_watermark(HeapWord* w);
447 inline void set_update_watermark_at_safepoint(HeapWord* w);
448
449 inline ShenandoahAffiliation affiliation() const;
450 inline const char* affiliation_name() const;
451
452 void set_affiliation(ShenandoahAffiliation new_affiliation);
453
454 // Region ageing and rejuvenation
455 uint age() { return _age; }
456 CENSUS_NOISE(uint youth() { return _youth; })
457
458 void increment_age() {
459 const uint max_age = markWord::max_age;
460 assert(_age <= max_age, "Error");
461 if (_age++ >= max_age) {
462 _age = max_age; // clamp
463 }
464 }
465
466 void reset_age() {
467 CENSUS_NOISE(_youth += _age;)
468 _age = 0;
469 }
470
471 CENSUS_NOISE(void clear_youth() { _youth = 0; })
472
473 private:
474 void decrement_humongous_waste() const;
475 void do_commit();
476 void do_uncommit();
477
478 inline void internal_increase_live_data(size_t s);
479
480 void set_state(RegionState to);
481 };
482
483 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP