1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
27
28 #include "gc/shared/gc_globals.hpp"
29 #include "gc/shared/spaceDecorator.hpp"
30 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
31 #include "gc/shenandoah/shenandoahAsserts.hpp"
32 #include "gc/shenandoah/shenandoahHeap.hpp"
33 #include "gc/shenandoah/shenandoahPacer.hpp"
34 #include "gc/shenandoah/shenandoahPadding.hpp"
35 #include "utilities/sizes.hpp"
36
37 class VMStructs;
38 class ShenandoahHeapRegionStateConstant;
39
40 class ShenandoahHeapRegion {
41 friend class VMStructs;
42 friend class ShenandoahHeapRegionStateConstant;
43 private:
44 /*
45 Region state is described by a state machine. Transitions are guarded by
46 heap lock, which allows changing the state of several regions atomically.
47 Region states can be logically aggregated in groups.
48
49 "Empty":
50 .................................................................
51 . .
52 . .
53 . Uncommitted <------- Committed <------------------------\
54 . | | . |
55 . \---------v-----------/ . |
56 . | . |
57 .........................|....................................... |
58 | |
59 "Active": | |
60 .........................|....................................... |
61 . | . |
62 . /-----------------^-------------------\ . |
63 . | | . |
64 . v v "Humongous": . |
65 . Regular ---\-----\ ..................O................ . |
66 . | ^ | | . | . . |
67 . | | | | . *---------\ . . |
68 . v | | | . v v . . |
69 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
70 . ^ / | | . Pinned v | . . |
71 . | / | | . *<--------/ . . |
72 . | v | | . | . . |
73 . CsetPinned | | ..................O................ . |
74 . | | | . |
75 . \-----\---v-------------------/ . |
76 . | . |
77 .........................|....................................... |
78 | |
79 "Trash": | |
80 .........................|....................................... |
81 . | . |
82 . v . |
83 . Trash ---------------------------------------/
84 . .
85 . .
86 .................................................................
87
88 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
89 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
90
91 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
92 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
93 quick reclamation without actual cleaning up.
94
95 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
96 Can be done asynchronously and in bulk.
97
98 Note how internal transitions disallow logic bugs:
99 a) No region can go Empty, unless properly reclaimed/recycled;
100 b) No region can go Uncommitted, unless reclaimed/recycled first;
101 c) Only Regular regions can go to CSet;
102 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
103 e) Pinned cannot go CSet, thus it never moves;
104 f) Humongous cannot be used for regular allocations;
105 g) Humongous cannot go CSet, thus it never moves;
106 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
107 follow associated humongous starts, not pinnable/movable by themselves);
108 i) Empty cannot go Trash, avoiding useless work;
109 j) ...
110 */
111
112 enum RegionState {
113 _empty_uncommitted, // region is empty and has memory uncommitted
114 _empty_committed, // region is empty and has memory committed
115 _regular, // region is for regular allocations
116 _humongous_start, // region is the humongous start
117 _humongous_cont, // region is the humongous continuation
118 _pinned_humongous_start, // region is both humongous start and pinned
119 _cset, // region is in collection set
120 _pinned, // region is pinned
121 _pinned_cset, // region is pinned and in cset (evac failure path)
122 _trash, // region contains only trash
123 _REGION_STATES_NUM // last
124 };
125
126 static const char* region_state_to_string(RegionState s) {
127 switch (s) {
128 case _empty_uncommitted: return "Empty Uncommitted";
129 case _empty_committed: return "Empty Committed";
130 case _regular: return "Regular";
131 case _humongous_start: return "Humongous Start";
132 case _humongous_cont: return "Humongous Continuation";
133 case _pinned_humongous_start: return "Humongous Start, Pinned";
134 case _cset: return "Collection Set";
135 case _pinned: return "Pinned";
136 case _pinned_cset: return "Collection Set, Pinned";
137 case _trash: return "Trash";
138 default:
139 ShouldNotReachHere();
140 return "";
141 }
142 }
143
144 // This method protects from accidental changes in enum order:
145 int region_state_to_ordinal(RegionState s) const {
146 switch (s) {
147 case _empty_uncommitted: return 0;
148 case _empty_committed: return 1;
149 case _regular: return 2;
150 case _humongous_start: return 3;
151 case _humongous_cont: return 4;
152 case _cset: return 5;
153 case _pinned: return 6;
154 case _trash: return 7;
155 case _pinned_cset: return 8;
156 case _pinned_humongous_start: return 9;
157 default:
158 ShouldNotReachHere();
159 return -1;
160 }
161 }
162
163 void report_illegal_transition(const char* method);
164
165 public:
166 static const int region_states_num() {
167 return _REGION_STATES_NUM;
168 }
169
170 // Allowed transitions from the outside code:
171 void make_regular_allocation(ShenandoahRegionAffiliation affiliation);
172 void make_young_maybe();
173 void make_regular_bypass();
174 void make_humongous_start();
175 void make_humongous_cont();
176 void make_humongous_start_bypass(ShenandoahRegionAffiliation affiliation);
177 void make_humongous_cont_bypass(ShenandoahRegionAffiliation affiliation);
178 void make_pinned();
179 void make_unpinned();
180 void make_cset();
181 void make_trash();
182 void make_trash_immediate();
183 void make_empty();
184 void make_uncommitted();
185 void make_committed_bypass();
186
187 // Individual states:
188 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
189 bool is_empty_committed() const { return _state == _empty_committed; }
190 bool is_regular() const { return _state == _regular; }
191 bool is_humongous_continuation() const { return _state == _humongous_cont; }
192
193 // Participation in logical groups:
194 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
195 bool is_active() const { return !is_empty() && !is_trash(); }
196 bool is_trash() const { return _state == _trash; }
197 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
198 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
199 bool is_committed() const { return !is_empty_uncommitted(); }
200 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
201 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
202 inline bool is_young() const;
203 inline bool is_old() const;
204
205 // Macro-properties:
206 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
207 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
208
209 RegionState state() const { return _state; }
210 int state_ordinal() const { return region_state_to_ordinal(_state); }
211
212 void record_pin();
213 void record_unpin();
214 size_t pin_count() const;
215
216 void clear_young_lab_flags();
217 void set_young_lab_flag();
218 bool has_young_lab_flag();
219
220 private:
221 static size_t RegionCount;
222 static size_t RegionSizeBytes;
223 static size_t RegionSizeWords;
224 static size_t RegionSizeBytesShift;
225 static size_t RegionSizeWordsShift;
226 static size_t RegionSizeBytesMask;
227 static size_t RegionSizeWordsMask;
228 static size_t HumongousThresholdBytes;
229 static size_t HumongousThresholdWords;
230 static size_t MaxTLABSizeBytes;
231 static size_t MaxTLABSizeWords;
232
233 // Never updated fields
234 size_t const _index;
235 HeapWord* const _bottom;
236 HeapWord* const _end;
237
238 // Rarely updated fields
239 HeapWord* _new_top;
240 double _empty_time;
241
242 // Seldom updated fields
243 RegionState _state;
244 HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
245
246 // Frequently updated fields
247 HeapWord* _top;
248
249 size_t _tlab_allocs;
250 size_t _gclab_allocs;
251 size_t _plab_allocs;
252
253 bool _has_young_lab;
254
255 volatile size_t _live_data;
256 volatile size_t _critical_pins;
257
258 HeapWord* volatile _update_watermark;
259
260 uint _age;
261
262 public:
263 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
264
265 static const size_t MIN_NUM_REGIONS = 10;
266
267 // Return adjusted max heap size
268 static size_t setup_sizes(size_t max_heap_size);
269
270 double empty_time() {
271 return _empty_time;
272 }
273
274 inline static size_t required_regions(size_t bytes) {
275 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
276 }
277
278 inline static size_t region_count() {
279 return ShenandoahHeapRegion::RegionCount;
280 }
281
282 inline static size_t region_size_bytes() {
283 return ShenandoahHeapRegion::RegionSizeBytes;
284 }
285
286 inline static size_t region_size_words() {
287 return ShenandoahHeapRegion::RegionSizeWords;
288 }
289
290 inline static size_t region_size_bytes_shift() {
291 return ShenandoahHeapRegion::RegionSizeBytesShift;
292 }
293
294 inline static size_t region_size_words_shift() {
295 return ShenandoahHeapRegion::RegionSizeWordsShift;
296 }
297
298 inline static size_t region_size_bytes_mask() {
299 return ShenandoahHeapRegion::RegionSizeBytesMask;
300 }
301
302 inline static size_t region_size_words_mask() {
303 return ShenandoahHeapRegion::RegionSizeWordsMask;
304 }
305
306 // Convert to jint with sanity checking
307 inline static jint region_size_bytes_jint() {
308 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
309 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
310 }
311
312 // Convert to jint with sanity checking
313 inline static jint region_size_words_jint() {
314 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
315 return (jint)ShenandoahHeapRegion::RegionSizeWords;
316 }
317
318 // Convert to jint with sanity checking
319 inline static jint region_size_bytes_shift_jint() {
320 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
321 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
322 }
323
324 // Convert to jint with sanity checking
325 inline static jint region_size_words_shift_jint() {
326 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
327 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
328 }
329
330 inline static size_t humongous_threshold_bytes() {
331 return ShenandoahHeapRegion::HumongousThresholdBytes;
332 }
333
334 inline static size_t humongous_threshold_words() {
335 return ShenandoahHeapRegion::HumongousThresholdWords;
336 }
337
338 inline static size_t max_tlab_size_bytes() {
339 return ShenandoahHeapRegion::MaxTLABSizeBytes;
340 }
341
342 inline static size_t max_tlab_size_words() {
343 return ShenandoahHeapRegion::MaxTLABSizeWords;
344 }
345
346 inline size_t index() const {
347 return _index;
348 }
349
350 // Allocation (return nullptr if full)
351 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_words);
352
353 // Allocation (return nullptr if full)
354 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest req);
355
356 inline void clear_live_data();
357 void set_live_data(size_t s);
358
359 // Increase live data for newly allocated region
360 inline void increase_live_data_alloc_words(size_t s);
361
362 // Increase live data for region scanned with GC
363 inline void increase_live_data_gc_words(size_t s);
364
365 inline bool has_live() const;
366 inline size_t get_live_data_bytes() const;
367 inline size_t get_live_data_words() const;
368
369 inline size_t garbage() const;
370
371 void print_on(outputStream* st) const;
372
373 void recycle();
374
375 inline void begin_preemptible_coalesce_and_fill() {
376 _coalesce_and_fill_boundary = _bottom;
377 }
378
379 inline void end_preemptible_coalesce_and_fill() {
380 _coalesce_and_fill_boundary = _end;
381 }
382
383 inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
384 _coalesce_and_fill_boundary = next_focus;
385 }
386
387 inline HeapWord* resume_coalesce_and_fill() {
388 return _coalesce_and_fill_boundary;
389 }
390
391 // Coalesce contiguous spans of garbage objects by filling header and reregistering start locations with remembered set.
392 // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parseable. Return true iff
393 // region is completely coalesced and filled. Returns false if cancelled before task is complete.
394 bool oop_fill_and_coalesce();
395
396 // Like oop_fill_and_coalesce(), but without honoring cancellation requests.
397 bool oop_fill_and_coalesce_wo_cancel();
398
399 // During global collections, this service iterates through an old-gen heap region that is not part of collection
400 // set to fill and register ranges of dead memory. Note that live objects were previously registered. Some dead objects
401 // that are subsumed into coalesced ranges of dead memory need to be "unregistered".
402 void global_oop_iterate_and_fill_dead(OopIterateClosure* cl);
403 void oop_iterate_humongous(OopIterateClosure* cl);
404 void oop_iterate_humongous(OopIterateClosure* cl, HeapWord* start, size_t words);
405
406 // Invoke closure on every reference contained within the humongous object that spans this humongous
407 // region if the reference is contained within a DIRTY card and the reference is no more than words following
408 // start within the humongous object.
409 void oop_iterate_humongous_slice(OopIterateClosure* cl, bool dirty_only, HeapWord* start, size_t words, bool write_table);
410
411 HeapWord* block_start(const void* p) const;
412 size_t block_size(const HeapWord* p) const;
413 bool block_is_obj(const HeapWord* p) const { return p < top(); }
414
415 // Find humongous start region that this region belongs to
416 ShenandoahHeapRegion* humongous_start_region() const;
417
418 HeapWord* top() const { return _top; }
419 void set_top(HeapWord* v) { _top = v; }
420
421 HeapWord* new_top() const { return _new_top; }
422 void set_new_top(HeapWord* v) { _new_top = v; }
423
424 HeapWord* bottom() const { return _bottom; }
425 HeapWord* end() const { return _end; }
426
427 size_t capacity() const { return byte_size(bottom(), end()); }
428 size_t used() const { return byte_size(bottom(), top()); }
429 size_t free() const { return byte_size(top(), end()); }
430
431 // Does this region contain this address?
432 bool contains(HeapWord* p) const {
433 return (bottom() <= p) && (p < top());
434 }
435
436 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
437 void reset_alloc_metadata();
438 size_t get_shared_allocs() const;
439 size_t get_tlab_allocs() const;
440 size_t get_gclab_allocs() const;
441 size_t get_plab_allocs() const;
442
443 inline HeapWord* get_update_watermark() const;
444 inline void set_update_watermark(HeapWord* w);
445 inline void set_update_watermark_at_safepoint(HeapWord* w);
446
447 inline ShenandoahRegionAffiliation affiliation() const;
448
449 void set_affiliation(ShenandoahRegionAffiliation new_affiliation);
450
451 uint age() { return _age; }
452 void increment_age() { _age++; }
453 void decrement_age() { if (_age-- == 0) { _age = 0; } }
454 void reset_age() { _age = 0; }
455
456 // Sets all remembered set cards to dirty. Returns the number of regions spanned by the associated humongous object.
457 size_t promote_humongous();
458
459 private:
460 void do_commit();
461 void do_uncommit();
462
463 // This is an old-region that was not part of the collection set during a GLOBAL collection. We coalesce the dead
464 // objects, but do not need to register the live objects as they are already registered.
465 void global_oop_iterate_objects_and_fill_dead(OopIterateClosure* cl);
466
467 inline void internal_increase_live_data(size_t s);
468
469 void set_state(RegionState to);
470 };
471
472 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP