1 /*
2 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.
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_implementation/shenandoah/shenandoahAllocRequest.hpp"
28 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
29 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
30 #include "gc_implementation/shenandoah/shenandoahPacer.hpp"
31 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
32
33 class VMStructs;
34 class ShenandoahHeapRegionStateConstant;
35
36 class ShenandoahHeapRegion {
37 friend class VMStructs;
38 friend class ShenandoahHeapRegionStateConstant;
39 private:
40 /*
41 Region state is described by a state machine. Transitions are guarded by
42 heap lock, which allows changing the state of several regions atomically.
43 Region states can be logically aggregated in groups.
44
45 "Empty":
46 .................................................................
47 . .
48 . .
49 . Uncommitted <------- Committed <------------------------\
50 . | | . |
51 . \---------v-----------/ . |
52 . | . |
53 .........................|....................................... |
54 | |
55 "Active": | |
56 .........................|....................................... |
57 . | . |
58 . /-----------------^-------------------\ . |
59 . | | . |
60 . v v "Humongous": . |
61 . Regular ---\-----\ ..................O................ . |
62 . | ^ | | . | . . |
63 . | | | | . *---------\ . . |
64 . v | | | . v v . . |
65 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
66 . ^ / | | . Pinned v | . . |
67 . | / | | . *<--------/ . . |
68 . | v | | . | . . |
69 . CsetPinned | | ..................O................ . |
70 . | | | . |
71 . \-----\---v-------------------/ . |
72 . | . |
73 .........................|....................................... |
74 | |
75 "Trash": | |
76 .........................|....................................... |
77 . | . |
78 . v . |
79 . Trash ---------------------------------------/
80 . .
81 . .
82 .................................................................
83
84 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
85 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
86
87 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
88 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
89 quick reclamation without actual cleaning up.
90
91 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
92 Can be done asynchronously and in bulk.
93
94 Note how internal transitions disallow logic bugs:
95 a) No region can go Empty, unless properly reclaimed/recycled;
96 b) No region can go Uncommitted, unless reclaimed/recycled first;
97 c) Only Regular regions can go to CSet;
98 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
99 e) Pinned cannot go CSet, thus it never moves;
100 f) Humongous cannot be used for regular allocations;
101 g) Humongous cannot go CSet, thus it never moves;
102 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
103 follow associated humongous starts, not pinnable/movable by themselves);
104 i) Empty cannot go Trash, avoiding useless work;
105 j) ...
106 */
107
108 enum RegionState {
109 _empty_uncommitted, // region is empty and has memory uncommitted
110 _empty_committed, // region is empty and has memory committed
111 _regular, // region is for regular allocations
112 _humongous_start, // region is the humongous start
113 _humongous_cont, // region is the humongous continuation
114 _pinned_humongous_start, // region is both humongous start and pinned
115 _cset, // region is in collection set
116 _pinned, // region is pinned
117 _pinned_cset, // region is pinned and in cset (evac failure path)
118 _trash, // region contains only trash
119 _REGION_STATES_NUM // last
120 };
121
122 static const char* region_state_to_string(RegionState s) {
123 switch (s) {
124 case _empty_uncommitted: return "Empty Uncommitted";
125 case _empty_committed: return "Empty Committed";
126 case _regular: return "Regular";
127 case _humongous_start: return "Humongous Start";
128 case _humongous_cont: return "Humongous Continuation";
129 case _pinned_humongous_start: return "Humongous Start, Pinned";
130 case _cset: return "Collection Set";
131 case _pinned: return "Pinned";
132 case _pinned_cset: return "Collection Set, Pinned";
133 case _trash: return "Trash";
134 default:
135 ShouldNotReachHere();
136 return "";
137 }
138 }
139
140 // This method protects from accidental changes in enum order:
141 int region_state_to_ordinal(RegionState s) const {
142 switch (s) {
143 case _empty_uncommitted: return 0;
144 case _empty_committed: return 1;
145 case _regular: return 2;
146 case _humongous_start: return 3;
147 case _humongous_cont: return 4;
148 case _cset: return 5;
149 case _pinned: return 6;
150 case _trash: return 7;
151 case _pinned_cset: return 8;
152 case _pinned_humongous_start: return 9;
153 default:
154 ShouldNotReachHere();
155 return -1;
156 }
157 }
158
159 void report_illegal_transition(const char* method);
160
161 public:
162 static const int region_states_num() {
163 return _REGION_STATES_NUM;
164 }
165
166 // Allowed transitions from the outside code:
167 void make_regular_allocation();
168 void make_regular_bypass();
169 void make_humongous_start();
170 void make_humongous_cont();
171 void make_humongous_start_bypass();
172 void make_humongous_cont_bypass();
173 void make_pinned();
174 void make_unpinned();
175 void make_cset();
176 void make_trash();
177 void make_trash_immediate();
178 void make_empty();
179 void make_uncommitted();
180 void make_committed_bypass();
181
182 // Individual states:
183 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
184 bool is_empty_committed() const { return _state == _empty_committed; }
185 bool is_regular() const { return _state == _regular; }
186 bool is_humongous_continuation() const { return _state == _humongous_cont; }
187
188 // Participation in logical groups:
189 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
190 bool is_active() const { return !is_empty() && !is_trash(); }
191 bool is_trash() const { return _state == _trash; }
192 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
193 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
194 bool is_committed() const { return !is_empty_uncommitted(); }
195 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
196 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
197
198 // Macro-properties:
199 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
200 bool is_stw_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
201
202 RegionState state() const { return _state; }
203 int state_ordinal() const { return region_state_to_ordinal(_state); }
204
205 void record_pin();
206 void record_unpin();
207 size_t pin_count() const;
208
209 private:
210 static size_t RegionCount;
211 static size_t RegionSizeBytes;
212 static size_t RegionSizeWords;
213 static size_t RegionSizeBytesShift;
214 static size_t RegionSizeWordsShift;
215 static size_t RegionSizeBytesMask;
216 static size_t RegionSizeWordsMask;
217 static size_t HumongousThresholdBytes;
218 static size_t HumongousThresholdWords;
219 static size_t MaxTLABSizeBytes;
220 static size_t MaxTLABSizeWords;
221
222 // Never updated fields
223 size_t const _index;
224 HeapWord* const _bottom;
225 HeapWord* const _end;
226
227 // Rarely updated fields
228 HeapWord* _new_top;
229 double _empty_time;
230
231 // Seldom updated fields
232 RegionState _state;
233
234 // Frequently updated fields
235 HeapWord* _top;
236
237 size_t _tlab_allocs;
238 size_t _gclab_allocs;
239
240 volatile jint _live_data;
241 volatile jint _critical_pins;
242
243 HeapWord* volatile _update_watermark;
244
245 public:
246 ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed);
247
248 static const size_t MIN_NUM_REGIONS = 10;
249
250 // Return adjusted max heap size
251 static size_t setup_sizes(size_t max_heap_size);
252
253 double empty_time() {
254 return _empty_time;
255 }
256
257 inline static size_t required_regions(size_t bytes) {
258 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
259 }
260
261 inline static size_t region_count() {
262 return ShenandoahHeapRegion::RegionCount;
263 }
264
265 inline static size_t region_size_bytes() {
266 return ShenandoahHeapRegion::RegionSizeBytes;
267 }
268
269 inline static size_t region_size_words() {
270 return ShenandoahHeapRegion::RegionSizeWords;
271 }
272
273 inline static size_t region_size_bytes_shift() {
274 return ShenandoahHeapRegion::RegionSizeBytesShift;
275 }
276
277 inline static size_t region_size_words_shift() {
278 return ShenandoahHeapRegion::RegionSizeWordsShift;
279 }
280
281 inline static size_t region_size_bytes_mask() {
282 return ShenandoahHeapRegion::RegionSizeBytesMask;
283 }
284
285 inline static size_t region_size_words_mask() {
286 return ShenandoahHeapRegion::RegionSizeWordsMask;
287 }
288
289 // Convert to jint with sanity checking
290 inline static jint region_size_bytes_jint() {
291 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
292 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
293 }
294
295 // Convert to jint with sanity checking
296 inline static jint region_size_words_jint() {
297 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
298 return (jint)ShenandoahHeapRegion::RegionSizeWords;
299 }
300
301 // Convert to jint with sanity checking
302 inline static jint region_size_bytes_shift_jint() {
303 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
304 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
305 }
306
307 // Convert to jint with sanity checking
308 inline static jint region_size_words_shift_jint() {
309 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
310 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
311 }
312
313 inline static size_t humongous_threshold_bytes() {
314 return ShenandoahHeapRegion::HumongousThresholdBytes;
315 }
316
317 inline static size_t humongous_threshold_words() {
318 return ShenandoahHeapRegion::HumongousThresholdWords;
319 }
320
321 inline static size_t max_tlab_size_bytes() {
322 return ShenandoahHeapRegion::MaxTLABSizeBytes;
323 }
324
325 inline static size_t max_tlab_size_words() {
326 return ShenandoahHeapRegion::MaxTLABSizeWords;
327 }
328
329 inline size_t index() const {
330 return _index;
331 }
332
333 // Allocation (return NULL if full)
334 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
335
336 inline void clear_live_data();
337 void set_live_data(size_t s);
338
339 // Increase live data for newly allocated region
340 inline void increase_live_data_alloc_words(size_t s);
341
342 // Increase live data for region scanned with GC
343 inline void increase_live_data_gc_words(size_t s);
344
345 inline bool has_live() const;
346 inline size_t get_live_data_bytes() const;
347 inline size_t get_live_data_words() const;
348
349 inline size_t garbage() const;
350
351 void print_on(outputStream* st) const;
352
353 void recycle();
354
355 HeapWord* block_start(const void* p) const;
356 size_t block_size(const HeapWord* p) const;
357 bool block_is_obj(const HeapWord* p) const { return p < top(); }
358
359 // Find humongous start region that this region belongs to
360 ShenandoahHeapRegion* humongous_start_region() const;
361
362 HeapWord* top() const { return _top; }
363 void set_top(HeapWord* v) { _top = v; }
364
365 HeapWord* new_top() const { return _new_top; }
366 void set_new_top(HeapWord* v) { _new_top = v; }
367
368 HeapWord* bottom() const { return _bottom; }
369 HeapWord* end() const { return _end; }
370
371 size_t capacity() const { return byte_size(bottom(), end()); }
372 size_t used() const { return byte_size(bottom(), top()); }
373 size_t free() const { return byte_size(top(), end()); }
374
375 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
376 void reset_alloc_metadata();
377 size_t get_shared_allocs() const;
378 size_t get_tlab_allocs() const;
379 size_t get_gclab_allocs() const;
380
381 inline HeapWord* get_update_watermark() const;
382 inline void set_update_watermark(HeapWord* w);
383 inline void set_update_watermark_at_safepoint(HeapWord* w);
384
385 private:
386 void do_commit();
387 void do_uncommit();
388
389 inline void internal_increase_live_data(size_t s);
390
391 void set_state(RegionState to);
392 };
393
394 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP