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/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/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 static const char* region_state_to_string(RegionState s) {
126 switch (s) {
127 case _empty_uncommitted: return "Empty Uncommitted";
128 case _empty_committed: return "Empty Committed";
129 case _regular: return "Regular";
130 case _humongous_start: return "Humongous Start";
131 case _humongous_cont: return "Humongous Continuation";
132 case _pinned_humongous_start: return "Humongous Start, Pinned";
133 case _cset: return "Collection Set";
134 case _pinned: return "Pinned";
135 case _pinned_cset: return "Collection Set, Pinned";
136 case _trash: return "Trash";
137 default:
138 ShouldNotReachHere();
139 return "";
140 }
141 }
142
143 // This method protects from accidental changes in enum order:
144 int region_state_to_ordinal(RegionState s) const {
145 switch (s) {
146 case _empty_uncommitted: return 0;
147 case _empty_committed: return 1;
148 case _regular: return 2;
149 case _humongous_start: return 3;
150 case _humongous_cont: return 4;
151 case _cset: return 5;
152 case _pinned: return 6;
153 case _trash: return 7;
154 case _pinned_cset: return 8;
155 case _pinned_humongous_start: return 9;
156 default:
157 ShouldNotReachHere();
158 return -1;
159 }
160 }
161
162 void report_illegal_transition(const char* method);
163
164 public:
165 static int region_states_num() {
166 return _REGION_STATES_NUM;
167 }
168
169 // Allowed transitions from the outside code:
170 void make_regular_allocation();
171 void make_regular_bypass();
172 void make_humongous_start();
173 void make_humongous_cont();
174 void make_humongous_start_bypass();
175 void make_humongous_cont_bypass();
176 void make_pinned();
177 void make_unpinned();
178 void make_cset();
179 void make_trash();
180 void make_trash_immediate();
181 void make_empty();
182 void make_uncommitted();
183 void make_committed_bypass();
184
185 // Individual states:
186 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
187 bool is_empty_committed() const { return _state == _empty_committed; }
188 bool is_regular() const { return _state == _regular; }
189 bool is_humongous_continuation() const { return _state == _humongous_cont; }
190
191 // Participation in logical groups:
192 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
193 bool is_active() const { return !is_empty() && !is_trash(); }
194 bool is_trash() const { return _state == _trash; }
195 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
196 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
197 bool is_committed() const { return !is_empty_uncommitted(); }
198 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
199 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
200
201 // Macro-properties:
202 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
203 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
204
205 RegionState state() const { return _state; }
206 int state_ordinal() const { return region_state_to_ordinal(_state); }
207
208 void record_pin();
209 void record_unpin();
210 size_t pin_count() const;
211
212 private:
213 static size_t RegionCount;
214 static size_t RegionSizeBytes;
215 static size_t RegionSizeWords;
216 static size_t RegionSizeBytesShift;
217 static size_t RegionSizeWordsShift;
218 static size_t RegionSizeBytesMask;
219 static size_t RegionSizeWordsMask;
220 static size_t MaxTLABSizeBytes;
221 static size_t MaxTLABSizeWords;
222
223 // Never updated fields
224 size_t const _index;
225 HeapWord* const _bottom;
226 HeapWord* const _end;
227
228 // Rarely updated fields
229 HeapWord* _new_top;
230 double _empty_time;
231
232 // Seldom updated fields
233 RegionState _state;
234
235 // Frequently updated fields
236 HeapWord* _top;
237
238 size_t _tlab_allocs;
239 size_t _gclab_allocs;
240
241 volatile size_t _live_data;
242 volatile size_t _critical_pins;
243
244 HeapWord* volatile _update_watermark;
245
246 public:
247 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
248
249 static const size_t MIN_NUM_REGIONS = 10;
250
251 // Return adjusted max heap size
252 static size_t setup_sizes(size_t max_heap_size);
253
254 double empty_time() {
255 return _empty_time;
256 }
257
258 inline static size_t required_regions(size_t bytes) {
259 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
260 }
261
262 inline static bool requires_humongous(size_t words) {
263 return words > ShenandoahHeapRegion::RegionSizeWords;
264 }
265
266 inline static size_t region_count() {
267 return ShenandoahHeapRegion::RegionCount;
268 }
269
270 inline static size_t region_size_bytes() {
271 return ShenandoahHeapRegion::RegionSizeBytes;
272 }
273
274 inline static size_t region_size_words() {
275 return ShenandoahHeapRegion::RegionSizeWords;
276 }
277
278 inline static size_t region_size_bytes_shift() {
279 return ShenandoahHeapRegion::RegionSizeBytesShift;
280 }
281
282 inline static size_t region_size_words_shift() {
283 return ShenandoahHeapRegion::RegionSizeWordsShift;
284 }
285
286 inline static size_t region_size_bytes_mask() {
287 return ShenandoahHeapRegion::RegionSizeBytesMask;
288 }
289
290 inline static size_t region_size_words_mask() {
291 return ShenandoahHeapRegion::RegionSizeWordsMask;
292 }
293
294 // Convert to jint with sanity checking
295 inline static jint region_size_bytes_jint() {
296 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
297 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
298 }
299
300 // Convert to jint with sanity checking
301 inline static jint region_size_words_jint() {
302 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
303 return (jint)ShenandoahHeapRegion::RegionSizeWords;
304 }
305
306 // Convert to jint with sanity checking
307 inline static jint region_size_bytes_shift_jint() {
308 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
309 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
310 }
311
312 // Convert to jint with sanity checking
313 inline static jint region_size_words_shift_jint() {
314 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
315 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
316 }
317
318 inline static size_t max_tlab_size_bytes() {
319 return ShenandoahHeapRegion::MaxTLABSizeBytes;
320 }
321
322 inline static size_t max_tlab_size_words() {
323 return ShenandoahHeapRegion::MaxTLABSizeWords;
324 }
325
326 inline size_t index() const {
327 return _index;
328 }
329
330 // Allocation (return null if full)
331 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
332
333 inline void clear_live_data();
334 void set_live_data(size_t s);
335
336 // Increase live data for newly allocated region
337 inline void increase_live_data_alloc_words(size_t s);
338
339 // Increase live data for region scanned with GC
340 inline void increase_live_data_gc_words(size_t s);
341
342 inline bool has_live() const;
343 inline size_t get_live_data_bytes() const;
344 inline size_t get_live_data_words() const;
345
346 inline size_t garbage() const;
347
348 void print_on(outputStream* st) const;
349
350 void recycle();
351
352 void oop_iterate(OopIterateClosure* cl);
353
354 HeapWord* block_start(const void* p) const;
355 size_t block_size(const HeapWord* p) const;
356 bool block_is_obj(const HeapWord* p) const { return p < top(); }
357
358 // Find humongous start region that this region belongs to
359 ShenandoahHeapRegion* humongous_start_region() const;
360
361 HeapWord* top() const { return _top; }
362 void set_top(HeapWord* v) { _top = v; }
363
364 HeapWord* new_top() const { return _new_top; }
365 void set_new_top(HeapWord* v) { _new_top = v; }
366
367 HeapWord* bottom() const { return _bottom; }
368 HeapWord* end() const { return _end; }
369
370 size_t capacity() const { return byte_size(bottom(), end()); }
371 size_t used() const { return byte_size(bottom(), top()); }
372 size_t free() const { return byte_size(top(), end()); }
373
374 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
375 void reset_alloc_metadata();
376 size_t get_shared_allocs() const;
377 size_t get_tlab_allocs() const;
378 size_t get_gclab_allocs() const;
379
380 inline HeapWord* get_update_watermark() const;
381 inline void set_update_watermark(HeapWord* w);
382 inline void set_update_watermark_at_safepoint(HeapWord* w);
383
384 private:
385 void do_commit();
386 void do_uncommit();
387
388 void oop_iterate_objects(OopIterateClosure* cl);
389 void oop_iterate_humongous(OopIterateClosure* cl);
390
391 inline void internal_increase_live_data(size_t s);
392
393 void set_state(RegionState to);
394 };
395
396 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP