1 /*
2 * Copyright (c) 2013, 2017, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP
26
27 #include "gc/shared/space.hpp"
28 #include "memory/universe.hpp"
29 #include "utilities/sizes.hpp"
30
31 class VMStructs;
32 class ShenandoahHeap;
33
34 class ShenandoahHeapRegion : public ContiguousSpace {
35 friend class VMStructs;
36 private:
37 /*
38 Region state is described by a state machine. Transitions are guarded by
39 heap lock, which allows changing the state of several regions atomically.
40 Region states can be logically aggregated in groups.
41
42 "Empty":
43 .................................................................
44 . .
45 . .
46 . Uncommitted <------- Committed <------------------------\
47 . | | . |
48 . \---------v-----------/ . |
49 . | . |
50 .........................|....................................... |
51 | |
52 "Active": | |
53 .........................|....................................... |
54 . | . |
55 . /-----------------^-------------------\ . |
56 . | | . |
57 . v v "Humongous": . |
58 . Regular ---\-----\ ..................O................ . |
59 . | ^ | | . | . . |
60 . | | | | . *---------\ . . |
61 . v | | | . v v . . |
62 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
63 . ^ / | | . Pinned v | . . |
64 . | / | | . *<--------/ . . |
65 . | v | | . | . . |
66 . CsetPinned | | ..................O................ . |
67 . | | | . |
68 . \-----\---v-------------------/ . |
69 . | . |
70 .........................|....................................... |
71 | |
72 "Trash": | |
73 .........................|....................................... |
74 . | . |
75 . v . |
76 . Trash ---------------------------------------/
77 . .
78 . .
79 .................................................................
80
81 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
82 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
83
84 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
85 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
86 quick reclamation without actual cleaning up.
87
88 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
89 Can be done asynchronously and in bulk.
90
91 Note how internal transitions disallow logic bugs:
92 a) No region can go Empty, unless properly reclaimed/recycled;
93 b) No region can go Uncommitted, unless reclaimed/recycled first;
94 c) Only Regular regions can go to CSet;
95 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
96 e) Pinned cannot go CSet, thus it never moves;
97 f) Humongous cannot be used for regular allocations;
98 g) Humongous cannot go CSet, thus it never moves;
99 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
100 follow associated humongous starts, not pinnable/movable by themselves);
101 i) Empty cannot go Trash, avoiding useless work;
102 j) ...
103 */
104
105 enum RegionState {
106 _empty_uncommitted, // region is empty and has memory uncommitted
107 _empty_committed, // region is empty and has memory committed
108 _regular, // region is for regular allocations
109 _humongous_start, // region is the humongous start
110 _humongous_cont, // region is the humongous continuation
111 _pinned_humongous_start, // region is both humongous start and pinned
112 _cset, // region is in collection set
113 _pinned, // region is pinned
114 _pinned_cset, // region is pinned and in cset (evac failure path)
115 _trash, // region contains only trash
116 };
117
118 const char* region_state_to_string(RegionState s) const {
119 switch (s) {
120 case _empty_uncommitted: return "Empty Uncommitted";
121 case _empty_committed: return "Empty Committed";
122 case _regular: return "Regular";
123 case _humongous_start: return "Humongous Start";
124 case _humongous_cont: return "Humongous Continuation";
125 case _pinned_humongous_start: return "Humongous Start, Pinned";
126 case _cset: return "Collection Set";
127 case _pinned: return "Pinned";
128 case _pinned_cset: return "Collection Set, Pinned";
129 case _trash: return "Trash";
130 default:
131 ShouldNotReachHere();
132 return "";
133 }
134 }
135
136 // This method protects from accidental changes in enum order:
137 int region_state_to_ordinal(RegionState s) const {
138 switch (s) {
139 case _empty_uncommitted: return 0;
140 case _empty_committed: return 1;
141 case _regular: return 2;
142 case _humongous_start: return 3;
143 case _humongous_cont: return 4;
144 case _cset: return 5;
145 case _pinned: return 6;
146 case _trash: return 7;
147 case _pinned_cset: return 8;
148 case _pinned_humongous_start: return 9;
149 default:
150 ShouldNotReachHere();
151 return -1;
152 }
153 }
154
155 void report_illegal_transition(const char* method);
156
157 void make_idle();
158 void activate_region();
159
160 bool can_idle_region() const;
161 public:
162 // Allowed transitions from the outside code:
163 void make_regular_allocation();
164 void make_regular_bypass();
165 void make_humongous_start();
166 void make_humongous_cont();
167 void make_humongous_start_bypass();
168 void make_humongous_cont_bypass();
169 void make_pinned();
170 void make_unpinned();
171 void make_cset();
172 void make_trash();
173 void make_empty();
174 void make_uncommitted();
175 void make_committed_bypass();
176
177 // Individual states:
178 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
179 bool is_empty_committed() const { return _state == _empty_committed; }
180 bool is_regular() const { return _state == _regular; }
181 bool is_humongous_continuation() const { return _state == _humongous_cont; }
182
183 // Participation in logical groups:
184 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
185 bool is_active() const { return !is_empty() && !is_trash(); }
186 bool is_trash() const { return _state == _trash; }
187 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
188 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
189 bool is_committed() const { return !is_empty_uncommitted(); }
190 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
191 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
192
193 // Macro-properties:
194 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
195 bool is_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
196
197 RegionState state() const { return _state; }
198 int state_ordinal() const { return region_state_to_ordinal(_state); }
199
200 private:
201 static size_t RegionSizeBytes;
202 static size_t RegionSizeWords;
203 static size_t RegionSizeBytesShift;
204 static size_t RegionSizeWordsShift;
205 static size_t RegionSizeBytesMask;
206 static size_t RegionSizeWordsMask;
207 static size_t HumongousThresholdBytes;
208 static size_t HumongousThresholdWords;
209 static size_t MaxTLABSizeBytes;
210
211 // Global alloaction counter, increased for each allocation
212 // under Shenandoah heap lock
213 static uint64_t AllocSeqNum;
214
215 ShenandoahHeap* _heap;
216 size_t _region_number;
217 volatile size_t _live_data;
218 MemRegion _reserved;
219
220 size_t _tlab_allocs;
221 size_t _gclab_allocs;
222 size_t _shared_allocs;
223
224 bool _root;
225
226 HeapWord* _new_top;
227
228 size_t _critical_pins;
229
230 // Seq numbers are used to drive heuristics decisions for collection.
231 // They are set when the region is used for allocation.
232 uint64_t _seqnum_first_alloc_mutator;
233 uint64_t _seqnum_first_alloc_gc;
234 uint64_t _seqnum_last_alloc_mutator;
235 uint64_t _seqnum_last_alloc_gc;
236
237 RegionState _state;
238 double _empty_time;
239
240 // If the region has been initially committed. It has been committed before
241 // it can be idled
242 bool _initialized;
243
244 ShenandoahPacer* _pacer;
245
246 public:
247 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
248
249 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
250
251 double empty_time() {
252 return _empty_time;
253 }
254
255 inline static size_t required_regions(size_t bytes) {
256 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
257 }
258
259 inline static size_t region_size_bytes() {
260 return ShenandoahHeapRegion::RegionSizeBytes;
261 }
262
263 inline static size_t region_size_words() {
264 return ShenandoahHeapRegion::RegionSizeWords;
265 }
266
267 inline static size_t region_size_bytes_shift() {
268 return ShenandoahHeapRegion::RegionSizeBytesShift;
269 }
270
271 inline static size_t region_size_words_shift() {
272 return ShenandoahHeapRegion::RegionSizeWordsShift;
273 }
274
275 inline static size_t region_size_bytes_mask() {
276 return ShenandoahHeapRegion::RegionSizeBytesMask;
277 }
278
279 inline static size_t region_size_words_mask() {
280 return ShenandoahHeapRegion::RegionSizeWordsMask;
281 }
282
283 // Convert to jint with sanity checking
284 inline static jint region_size_bytes_jint() {
285 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
286 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
287 }
288
289 // Convert to jint with sanity checking
290 inline static jint region_size_words_jint() {
291 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
292 return (jint)ShenandoahHeapRegion::RegionSizeWords;
293 }
294
295 // Convert to jint with sanity checking
296 inline static jint region_size_bytes_shift_jint() {
297 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
298 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
299 }
300
301 // Convert to jint with sanity checking
302 inline static jint region_size_words_shift_jint() {
303 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
304 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
305 }
306
307 inline static size_t humongous_threshold_bytes() {
308 return ShenandoahHeapRegion::HumongousThresholdBytes;
309 }
310
311 inline static size_t humongous_threshold_words() {
312 return ShenandoahHeapRegion::HumongousThresholdWords;
313 }
314
315 inline static size_t max_tlab_size_bytes() {
316 return ShenandoahHeapRegion::MaxTLABSizeBytes;
317 }
318
319 static uint64_t seqnum_current_alloc() {
320 // Last used seq number
321 return AllocSeqNum - 1;
322 }
323
324 size_t region_number() const;
325
326 // Allocation (return NULL if full)
327 inline HeapWord* allocate(size_t word_size, ShenandoahHeap::AllocType type);
328 HeapWord* allocate(size_t word_size) {
329 // ContiguousSpace wants us to have this method. But it is an error to call this with Shenandoah.
330 ShouldNotCallThis();
331 return NULL;
332 }
333
334 // Roll back the previous allocation of an object with specified size.
335 // Returns TRUE when successful, FALSE if not successful or not supported.
336 bool rollback_allocation(uint size);
337
338 void clear_live_data();
339 void set_live_data(size_t s);
340
341 // Increase live data for newly allocated region
342 inline void increase_live_data_alloc_words(size_t s);
343
344 // Increase live data for region scanned with GC
345 inline void increase_live_data_gc_words(size_t s);
346
347 bool has_live() const;
348 size_t get_live_data_bytes() const;
349 size_t get_live_data_words() const;
350
351 void print_on(outputStream* st) const;
352
353 size_t garbage() const;
354
355 void recycle();
356
357 void oop_iterate(ExtendedOopClosure* cl);
358
359 HeapWord* block_start_const(const void* p) const;
360
361 // Just before GC we need to fill the current region.
362 void fill_region();
363
364 bool in_collection_set() const;
365
366 // Find humongous start region that this region belongs to
367 ShenandoahHeapRegion* humongous_start_region() const;
368
369 virtual CompactibleSpace* next_compaction_space() const;
370
371 // Override for scan_and_forward support.
372 void prepare_for_compaction(CompactPoint* cp);
373 void adjust_pointers();
374 void compact();
375
376 void set_new_top(HeapWord* new_top) { _new_top = new_top; }
377 HeapWord* new_top() const { return _new_top; }
378
379 void set_root(bool r) {
380 _root = r;
381 }
382 bool is_root() const {
383 return _root;
384 }
385
386 inline void adjust_alloc_metadata(ShenandoahHeap::AllocType type, size_t);
387 void reset_alloc_metadata_to_shared();
388 void reset_alloc_metadata();
389 size_t get_shared_allocs() const;
390 size_t get_tlab_allocs() const;
391 size_t get_gclab_allocs() const;
392
393 uint64_t seqnum_first_alloc() const {
394 if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc;
395 if (_seqnum_first_alloc_gc == 0) return _seqnum_first_alloc_mutator;
396 return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc);
397 }
398
399 uint64_t seqnum_last_alloc() const {
400 return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc);
401 }
402
403 uint64_t seqnum_first_alloc_mutator() const {
404 return _seqnum_first_alloc_mutator;
405 }
406
407 uint64_t seqnum_last_alloc_mutator() const {
408 return _seqnum_last_alloc_mutator;
409 }
410
411 uint64_t seqnum_first_alloc_gc() const {
412 return _seqnum_first_alloc_gc;
413 }
414
415 uint64_t seqnum_last_alloc_gc() const {
416 return _seqnum_last_alloc_gc;
417 }
418
419 private:
420 void do_commit();
421 void do_uncommit();
422
423 void oop_iterate_objects(ExtendedOopClosure* cl);
424 void oop_iterate_humongous(ExtendedOopClosure* cl);
425
426 inline void internal_increase_live_data(size_t s);
427 };
428
429 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP