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 MaxTLABSizeBytes;
232 static size_t MaxTLABSizeWords;
233
234 // Never updated fields
235 size_t const _index;
236 HeapWord* const _bottom;
237 HeapWord* const _end;
238
239 // Rarely updated fields
240 HeapWord* _new_top;
241 double _empty_time;
242
243 HeapWord* _top_before_promoted;
244
245 // Seldom updated fields
246 RegionState _state;
247 HeapWord* _coalesce_and_fill_boundary; // for old regions not selected as collection set candidates.
248
249 // Frequently updated fields
250 HeapWord* _top;
251
252 size_t _tlab_allocs;
253 size_t _gclab_allocs;
254 size_t _plab_allocs;
255
256 volatile size_t _live_data;
257 volatile size_t _critical_pins;
258
259 HeapWord* volatile _update_watermark;
260
261 uint _age;
262 CENSUS_NOISE(uint _youth;) // tracks epochs of retrograde ageing (rejuvenation)
263
264 public:
265 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
266
267 static const size_t MIN_NUM_REGIONS = 10;
268
269 // Return adjusted max heap size
270 static size_t setup_sizes(size_t max_heap_size);
271
272 double empty_time() {
273 return _empty_time;
274 }
275
276 inline static size_t required_regions(size_t bytes) {
277 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
278 }
279
280 inline static bool requires_humongous(size_t words) {
281 return words > ShenandoahHeapRegion::RegionSizeWords;
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 max_tlab_size_bytes() {
337 return ShenandoahHeapRegion::MaxTLABSizeBytes;
338 }
339
340 inline static size_t max_tlab_size_words() {
341 return ShenandoahHeapRegion::MaxTLABSizeWords;
342 }
343
344 inline size_t index() const {
345 return _index;
346 }
347
348 inline void save_top_before_promote();
349 inline HeapWord* get_top_before_promote() const { return _top_before_promoted; }
350 inline void restore_top_before_promote();
351 inline size_t garbage_before_padded_for_promote() const;
352
353 // If next available memory is not aligned on address that is multiple of alignment, fill the empty space
354 // so that returned object is aligned on an address that is a multiple of alignment_in_bytes. Requested
355 // size is in words. It is assumed that this->is_old(). A pad object is allocated, filled, and registered
356 // if necessary to assure the new allocation is properly aligned. Return nullptr if memory is not available.
357 inline HeapWord* allocate_aligned(size_t word_size, ShenandoahAllocRequest &req, size_t alignment_in_bytes);
358
359 // Allocation (return nullptr if full)
360 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest req);
361
362 inline void clear_live_data();
363 void set_live_data(size_t s);
364
365 // Increase live data for newly allocated region
366 inline void increase_live_data_alloc_words(size_t s);
367
368 // Increase live data for region scanned with GC
369 inline void increase_live_data_gc_words(size_t s);
370
371 inline bool has_live() const;
372 inline size_t get_live_data_bytes() const;
373 inline size_t get_live_data_words() const;
374
375 inline size_t garbage() const;
376
377 void print_on(outputStream* st) const;
378
379 void recycle();
380
381 inline void begin_preemptible_coalesce_and_fill() {
382 _coalesce_and_fill_boundary = _bottom;
383 }
384
385 inline void end_preemptible_coalesce_and_fill() {
386 _coalesce_and_fill_boundary = _end;
387 }
388
389 inline void suspend_coalesce_and_fill(HeapWord* next_focus) {
390 _coalesce_and_fill_boundary = next_focus;
391 }
392
393 inline HeapWord* resume_coalesce_and_fill() {
394 return _coalesce_and_fill_boundary;
395 }
396
397 // Coalesce contiguous spans of garbage objects by filling header and registering start locations with remembered set.
398 // This is used by old-gen GC following concurrent marking to make old-gen HeapRegions parsable. Old regions must be
399 // parsable because the mark bitmap is not reliable during the concurrent old mark.
400 // Return true iff region is completely coalesced and filled. Returns false if cancelled before task is complete.
401 bool oop_coalesce_and_fill(bool cancellable);
402
403 // Invoke closure on every reference contained within the humongous object that spans this humongous
404 // region if the reference is contained within a DIRTY card and the reference is no more than words following
405 // start within the humongous object.
406 void oop_iterate_humongous_slice_dirty(OopIterateClosure* cl, HeapWord* start, size_t words, bool write_table) const;
407
408 // Invoke closure on every reference contained within the humongous object starting from start and
409 // ending at start + words.
410 void oop_iterate_humongous_slice_all(OopIterateClosure* cl, HeapWord* start, size_t words) const;
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() const { return _age; }
456 CENSUS_NOISE(uint youth() const { 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