1 /*
2 * Copyright (c) 2013, 2019, 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/spaceDecorator.hpp"
29 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc/shenandoah/shenandoahAsserts.hpp"
31 #include "gc/shenandoah/shenandoahHeap.hpp"
32 #include "gc/shenandoah/shenandoahPacer.hpp"
33 #include "gc/shenandoah/shenandoahPadding.hpp"
34 #include "utilities/sizes.hpp"
35
36 class VMStructs;
37 class ShenandoahHeapRegionStateConstant;
38
39 class ShenandoahHeapRegion {
40 friend class VMStructs;
41 friend class ShenandoahHeapRegionStateConstant;
42 private:
43 /*
44 Region state is described by a state machine. Transitions are guarded by
45 heap lock, which allows changing the state of several regions atomically.
46 Region states can be logically aggregated in groups.
47
48 "Empty":
49 .................................................................
50 . .
51 . .
52 . Uncommitted <------- Committed <------------------------\
53 . | | . |
54 . \---------v-----------/ . |
55 . | . |
56 .........................|....................................... |
57 | |
58 "Active": | |
59 .........................|....................................... |
60 . | . |
61 . /-----------------^-------------------\ . |
62 . | | . |
63 . v v "Humongous": . |
64 . Regular ---\-----\ ..................O................ . |
65 . | ^ | | . | . . |
66 . | | | | . *---------\ . . |
67 . v | | | . v v . . |
68 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
69 . ^ / | | . Pinned v | . . |
70 . | / | | . *<--------/ . . |
71 . | v | | . | . . |
72 . CsetPinned | | ..................O................ . |
73 . | | | . |
74 . \-----\---v-------------------/ . |
75 . | . |
76 .........................|....................................... |
77 | |
78 "Trash": | |
79 .........................|....................................... |
80 . | . |
81 . v . |
82 . Trash ---------------------------------------/
83 . .
84 . .
85 .................................................................
86
87 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
88 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
89
90 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
91 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
92 quick reclamation without actual cleaning up.
93
94 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
95 Can be done asynchronously and in bulk.
96
97 Note how internal transitions disallow logic bugs:
98 a) No region can go Empty, unless properly reclaimed/recycled;
99 b) No region can go Uncommitted, unless reclaimed/recycled first;
100 c) Only Regular regions can go to CSet;
101 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
102 e) Pinned cannot go CSet, thus it never moves;
103 f) Humongous cannot be used for regular allocations;
104 g) Humongous cannot go CSet, thus it never moves;
105 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
106 follow associated humongous starts, not pinnable/movable by themselves);
107 i) Empty cannot go Trash, avoiding useless work;
108 j) ...
109 */
110
111 enum RegionState {
112 _empty_uncommitted, // region is empty and has memory uncommitted
113 _empty_committed, // region is empty and has memory committed
114 _regular, // region is for regular allocations
115 _humongous_start, // region is the humongous start
116 _humongous_cont, // region is the humongous continuation
117 _pinned_humongous_start, // region is both humongous start and pinned
118 _cset, // region is in collection set
119 _pinned, // region is pinned
120 _pinned_cset, // region is pinned and in cset (evac failure path)
121 _trash, // region contains only trash
122 _REGION_STATES_NUM // last
123 };
124
125 // Future generalization may introduce additional generations, survivor, for example.
126 enum RegionGeneration {
127 _youngest_gen, // region is part of youngest generation, collected by Shenandoah
128 _oldest_gen // region is part of oldest generation, collected by concurrent mark and sweep
129 };
130
131 static const char* region_state_to_string(RegionState s) {
132 switch (s) {
133 case _empty_uncommitted: return "Empty Uncommitted";
134 case _empty_committed: return "Empty Committed";
135 case _regular: return "Regular";
136 case _humongous_start: return "Humongous Start";
137 case _humongous_cont: return "Humongous Continuation";
138 case _pinned_humongous_start: return "Humongous Start, Pinned";
139 case _cset: return "Collection Set";
140 case _pinned: return "Pinned";
141 case _pinned_cset: return "Collection Set, Pinned";
142 case _trash: return "Trash";
143 default:
144 ShouldNotReachHere();
145 return "";
146 }
147 }
148
149 // This method protects from accidental changes in enum order:
150 int region_state_to_ordinal(RegionState s) const {
151 switch (s) {
152 case _empty_uncommitted: return 0;
153 case _empty_committed: return 1;
154 case _regular: return 2;
155 case _humongous_start: return 3;
156 case _humongous_cont: return 4;
157 case _cset: return 5;
158 case _pinned: return 6;
159 case _trash: return 7;
160 case _pinned_cset: return 8;
161 case _pinned_humongous_start: return 9;
162 default:
163 ShouldNotReachHere();
164 return -1;
165 }
166 }
167
168 void report_illegal_transition(const char* method);
169
170 public:
171 static const int region_states_num() {
172 return _REGION_STATES_NUM;
173 }
174
175 // Allowed transitions from the outside code:
176 void make_regular_allocation();
177 void make_regular_bypass();
178 void make_humongous_start();
179 void make_humongous_cont();
180 void make_humongous_start_bypass();
181 void make_humongous_cont_bypass();
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
207 // Macro-properties:
208 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
209 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
210
211 RegionState state() const { return _state; }
212 int state_ordinal() const { return region_state_to_ordinal(_state); }
213
214 void record_pin();
215 void record_unpin();
216 size_t pin_count() const;
217
218 private:
219 static size_t RegionCount;
220 static size_t RegionSizeBytes;
221 static size_t RegionSizeWords;
222 static size_t RegionSizeBytesShift;
223 static size_t RegionSizeWordsShift;
224 static size_t RegionSizeBytesMask;
225 static size_t RegionSizeWordsMask;
226 static size_t HumongousThresholdBytes;
227 static size_t HumongousThresholdWords;
228 static size_t MaxTLABSizeBytes;
229 static size_t MaxTLABSizeWords;
230
231 // Never updated fields
232 size_t const _index;
233 HeapWord* const _bottom;
234 HeapWord* const _end;
235
236 // Rarely updated fields
237 HeapWord* _new_top;
238 double _empty_time;
239
240 // Frequently updated fields
241 HeapWord* _top;
242
243 size_t _tlab_allocs;
244 size_t _gclab_allocs;
245
246 volatile size_t _live_data;
247 volatile size_t _critical_pins;
248
249 HeapWord* volatile _update_watermark;
250
251 // Seldom updated fields
252 // (Of all fields, these two ints have least alignment constraint)
253 RegionState _state;
254 RegionGeneration _gen;
255
256 public:
257 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
258
259 static const size_t MIN_NUM_REGIONS = 10;
260
261 static void setup_sizes(size_t max_heap_size);
262
263 double empty_time() {
264 return _empty_time;
265 }
266
267 inline static size_t required_regions(size_t bytes) {
268 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
269 }
270
271 inline static size_t region_count() {
272 return ShenandoahHeapRegion::RegionCount;
273 }
274
275 inline static size_t region_size_bytes() {
276 return ShenandoahHeapRegion::RegionSizeBytes;
277 }
278
279 inline static size_t region_size_words() {
280 return ShenandoahHeapRegion::RegionSizeWords;
281 }
282
283 inline static size_t region_size_bytes_shift() {
284 return ShenandoahHeapRegion::RegionSizeBytesShift;
285 }
286
287 inline static size_t region_size_words_shift() {
288 return ShenandoahHeapRegion::RegionSizeWordsShift;
289 }
290
291 inline static size_t region_size_bytes_mask() {
292 return ShenandoahHeapRegion::RegionSizeBytesMask;
293 }
294
295 inline static size_t region_size_words_mask() {
296 return ShenandoahHeapRegion::RegionSizeWordsMask;
297 }
298
299 // Convert to jint with sanity checking
300 inline static jint region_size_bytes_jint() {
301 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
302 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
303 }
304
305 // Convert to jint with sanity checking
306 inline static jint region_size_words_jint() {
307 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
308 return (jint)ShenandoahHeapRegion::RegionSizeWords;
309 }
310
311 // Convert to jint with sanity checking
312 inline static jint region_size_bytes_shift_jint() {
313 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
314 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
315 }
316
317 // Convert to jint with sanity checking
318 inline static jint region_size_words_shift_jint() {
319 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
320 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
321 }
322
323 inline static size_t humongous_threshold_bytes() {
324 return ShenandoahHeapRegion::HumongousThresholdBytes;
325 }
326
327 inline static size_t humongous_threshold_words() {
328 return ShenandoahHeapRegion::HumongousThresholdWords;
329 }
330
331 inline static size_t max_tlab_size_bytes() {
332 return ShenandoahHeapRegion::MaxTLABSizeBytes;
333 }
334
335 inline static size_t max_tlab_size_words() {
336 return ShenandoahHeapRegion::MaxTLABSizeWords;
337 }
338
339 inline size_t index() const {
340 return _index;
341 }
342
343 // Allocation (return NULL if full)
344 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
345
346 inline void clear_live_data();
347 void set_live_data(size_t s);
348
349 // Increase live data for newly allocated region
350 inline void increase_live_data_alloc_words(size_t s);
351
352 // Increase live data for region scanned with GC
353 inline void increase_live_data_gc_words(size_t s);
354
355 inline bool has_live() const;
356 inline size_t get_live_data_bytes() const;
357 inline size_t get_live_data_words() const;
358
359 inline size_t garbage() const;
360
361 void print_on(outputStream* st) const;
362
363 void recycle();
364
365 void oop_iterate(OopIterateClosure* cl);
366
367 HeapWord* block_start(const void* p) const;
368 size_t block_size(const HeapWord* p) const;
369 bool block_is_obj(const HeapWord* p) const { return p < top(); }
370
371 // Find humongous start region that this region belongs to
372 ShenandoahHeapRegion* humongous_start_region() const;
373
374 HeapWord* top() const { return _top; }
375 void set_top(HeapWord* v) { _top = v; }
376
377 HeapWord* new_top() const { return _new_top; }
378 void set_new_top(HeapWord* v) { _new_top = v; }
379
380 HeapWord* bottom() const { return _bottom; }
381 HeapWord* end() const { return _end; }
382
383 size_t capacity() const { return byte_size(bottom(), end()); }
384 size_t used() const { return byte_size(bottom(), top()); }
385 size_t free() const { return byte_size(top(), end()); }
386
387 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
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 inline HeapWord* get_update_watermark() const;
394 inline void set_update_watermark(HeapWord* w);
395 inline void set_update_watermark_at_safepoint(HeapWord* w);
396
397 private:
398 void do_commit();
399 void do_uncommit();
400
401 void oop_iterate_objects(OopIterateClosure* cl);
402 void oop_iterate_humongous(OopIterateClosure* cl);
403
404 inline void internal_increase_live_data(size_t s);
405
406 void set_state(RegionState to);
407 };
408
409 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP