1 /*
2 * Copyright (c) 2013, 2018, 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 "memory/space.hpp"
28 #include "gc_implementation/shenandoah/shenandoahAllocRequest.hpp"
29 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
30 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
31 #include "gc_implementation/shenandoah/shenandoahPacer.hpp"
32
33 class VMStructs;
34
35 class ShenandoahHeapRegion : public ContiguousSpace {
36 friend class VMStructs;
37 private:
38 /*
39 Region state is described by a state machine. Transitions are guarded by
40 heap lock, which allows changing the state of several regions atomically.
41 Region states can be logically aggregated in groups.
42
43 "Empty":
44 .................................................................
45 . .
46 . .
47 . Uncommitted <------- Committed <------------------------\
48 . | | . |
49 . \---------v-----------/ . |
50 . | . |
51 .........................|....................................... |
52 | |
53 "Active": | |
54 .........................|....................................... |
55 . | . |
56 . /-----------------^-------------------\ . |
57 . | | . |
58 . v v "Humongous": . |
59 . Regular ---\-----\ ..................O................ . |
60 . | ^ | | . | . . |
61 . | | | | . *---------\ . . |
62 . v | | | . v v . . |
63 . Pinned Cset | . HStart <--> H/Start H/Cont . . |
64 . ^ / | | . Pinned v | . . |
65 . | / | | . *<--------/ . . |
66 . | v | | . | . . |
67 . CsetPinned | | ..................O................ . |
68 . | | | . |
69 . \-----\---v-------------------/ . |
70 . | . |
71 .........................|....................................... |
72 | |
73 "Trash": | |
74 .........................|....................................... |
75 . | . |
76 . v . |
77 . Trash ---------------------------------------/
78 . .
79 . .
80 .................................................................
81
82 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed}
83 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous.
84
85 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle,
86 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows
87 quick reclamation without actual cleaning up.
88
89 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata.
90 Can be done asynchronously and in bulk.
91
92 Note how internal transitions disallow logic bugs:
93 a) No region can go Empty, unless properly reclaimed/recycled;
94 b) No region can go Uncommitted, unless reclaimed/recycled first;
95 c) Only Regular regions can go to CSet;
96 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned;
97 e) Pinned cannot go CSet, thus it never moves;
98 f) Humongous cannot be used for regular allocations;
99 g) Humongous cannot go CSet, thus it never moves;
100 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should
101 follow associated humongous starts, not pinnable/movable by themselves);
102 i) Empty cannot go Trash, avoiding useless work;
103 j) ...
104 */
105
106 enum RegionState {
107 _empty_uncommitted, // region is empty and has memory uncommitted
108 _empty_committed, // region is empty and has memory committed
109 _regular, // region is for regular allocations
110 _humongous_start, // region is the humongous start
111 _humongous_cont, // region is the humongous continuation
112 _pinned_humongous_start, // region is both humongous start and pinned
113 _cset, // region is in collection set
114 _pinned, // region is pinned
115 _pinned_cset, // region is pinned and in cset (evac failure path)
116 _trash, // region contains only trash
117 };
118
119 const char* region_state_to_string(RegionState s) const {
120 switch (s) {
121 case _empty_uncommitted: return "Empty Uncommitted";
122 case _empty_committed: return "Empty Committed";
123 case _regular: return "Regular";
124 case _humongous_start: return "Humongous Start";
125 case _humongous_cont: return "Humongous Continuation";
126 case _pinned_humongous_start: return "Humongous Start, Pinned";
127 case _cset: return "Collection Set";
128 case _pinned: return "Pinned";
129 case _pinned_cset: return "Collection Set, Pinned";
130 case _trash: return "Trash";
131 default:
132 ShouldNotReachHere();
133 return "";
134 }
135 }
136
137 // This method protects from accidental changes in enum order:
138 int region_state_to_ordinal(RegionState s) const {
139 switch (s) {
140 case _empty_uncommitted: return 0;
141 case _empty_committed: return 1;
142 case _regular: return 2;
143 case _humongous_start: return 3;
144 case _humongous_cont: return 4;
145 case _cset: return 5;
146 case _pinned: return 6;
147 case _trash: return 7;
148 case _pinned_cset: return 8;
149 case _pinned_humongous_start: return 9;
150 default:
151 ShouldNotReachHere();
152 return -1;
153 }
154 }
155
156 void report_illegal_transition(const char* method);
157
158 public:
159 // Allowed transitions from the outside code:
160 void make_regular_allocation();
161 void make_regular_bypass();
162 void make_humongous_start();
163 void make_humongous_cont();
164 void make_humongous_start_bypass();
165 void make_humongous_cont_bypass();
166 void make_pinned();
167 void make_unpinned();
168 void make_cset();
169 void make_trash();
170 void make_trash_immediate();
171 void make_empty();
172 void make_uncommitted();
173 void make_committed_bypass();
174
175 // Individual states:
176 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; }
177 bool is_empty_committed() const { return _state == _empty_committed; }
178 bool is_regular() const { return _state == _regular; }
179 bool is_humongous_continuation() const { return _state == _humongous_cont; }
180
181 // Participation in logical groups:
182 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); }
183 bool is_active() const { return !is_empty() && !is_trash(); }
184 bool is_trash() const { return _state == _trash; }
185 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; }
186 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); }
187 bool is_committed() const { return !is_empty_uncommitted(); }
188 bool is_cset() const { return _state == _cset || _state == _pinned_cset; }
189 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; }
190
191 // Macro-properties:
192 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; }
193 bool is_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); }
194
195 RegionState state() const { return _state; }
196 int state_ordinal() const { return region_state_to_ordinal(_state); }
197
198 private:
199 static size_t RegionCount;
200 static size_t RegionSizeBytes;
201 static size_t RegionSizeWords;
202 static size_t RegionSizeBytesShift;
203 static size_t RegionSizeWordsShift;
204 static size_t RegionSizeBytesMask;
205 static size_t RegionSizeWordsMask;
206 static size_t HumongousThresholdBytes;
207 static size_t HumongousThresholdWords;
208 static size_t MaxTLABSizeBytes;
209 static size_t MaxTLABSizeWords;
210
211 // Never updated fields
212 ShenandoahHeap* _heap;
213 MemRegion _reserved;
214 size_t _region_number;
215
216 // Rarely updated fields
217 HeapWord* _new_top;
218 size_t _critical_pins;
219 double _empty_time;
220
221 // Seldom updated fields
222 RegionState _state;
223
224 // Frequently updated fields
225 size_t _tlab_allocs;
226 size_t _gclab_allocs;
227 size_t _shared_allocs;
228
229 volatile jint _live_data;
230
231 // Claim some space at the end to protect next region
232 char _pad0[DEFAULT_CACHE_LINE_SIZE];
233
234 public:
235 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
236
237 static const size_t MIN_NUM_REGIONS = 10;
238
239 static void setup_sizes(size_t initial_heap_size, size_t max_heap_size);
240
241 double empty_time() {
242 return _empty_time;
243 }
244
245 inline static size_t required_regions(size_t bytes) {
246 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
247 }
248
249 inline static size_t region_count() {
250 return ShenandoahHeapRegion::RegionCount;
251 }
252
253 inline static size_t region_size_bytes() {
254 return ShenandoahHeapRegion::RegionSizeBytes;
255 }
256
257 inline static size_t region_size_words() {
258 return ShenandoahHeapRegion::RegionSizeWords;
259 }
260
261 inline static size_t region_size_bytes_shift() {
262 return ShenandoahHeapRegion::RegionSizeBytesShift;
263 }
264
265 inline static size_t region_size_words_shift() {
266 return ShenandoahHeapRegion::RegionSizeWordsShift;
267 }
268
269 inline static size_t region_size_bytes_mask() {
270 return ShenandoahHeapRegion::RegionSizeBytesMask;
271 }
272
273 inline static size_t region_size_words_mask() {
274 return ShenandoahHeapRegion::RegionSizeWordsMask;
275 }
276
277 // Convert to jint with sanity checking
278 inline static jint region_size_bytes_jint() {
279 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
280 return (jint)ShenandoahHeapRegion::RegionSizeBytes;
281 }
282
283 // Convert to jint with sanity checking
284 inline static jint region_size_words_jint() {
285 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
286 return (jint)ShenandoahHeapRegion::RegionSizeWords;
287 }
288
289 // Convert to jint with sanity checking
290 inline static jint region_size_bytes_shift_jint() {
291 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
292 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
293 }
294
295 // Convert to jint with sanity checking
296 inline static jint region_size_words_shift_jint() {
297 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
298 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
299 }
300
301 inline static size_t humongous_threshold_bytes() {
302 return ShenandoahHeapRegion::HumongousThresholdBytes;
303 }
304
305 inline static size_t humongous_threshold_words() {
306 return ShenandoahHeapRegion::HumongousThresholdWords;
307 }
308
309 inline static size_t max_tlab_size_bytes() {
310 return ShenandoahHeapRegion::MaxTLABSizeBytes;
311 }
312
313 inline static size_t max_tlab_size_words() {
314 return ShenandoahHeapRegion::MaxTLABSizeWords;
315 }
316
317 size_t region_number() const;
318
319 // Allocation (return NULL if full)
320 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
321
322 HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL)
323
324 void clear_live_data();
325 void set_live_data(size_t s);
326
327 // Increase live data for newly allocated region
328 inline void increase_live_data_alloc_words(size_t s);
329
330 // Increase live data for region scanned with GC
331 inline void increase_live_data_gc_words(size_t s);
332
333 bool has_live() const;
334 size_t get_live_data_bytes() const;
335 size_t get_live_data_words() const;
336
337 void print_on(outputStream* st) const;
338
339 size_t garbage() const;
340
341 void recycle();
342
343 void oop_iterate_skip_unreachable(ExtendedOopClosure* cl, bool skip_unreachable_objects) shenandoah_not_implemented;
344 HeapWord* object_iterate_careful(ObjectClosureCareful* cl) shenandoah_not_implemented_return(NULL);
345
346 HeapWord* block_start_const(const void* p) const;
347
348 bool in_collection_set() const;
349
350 // Find humongous start region that this region belongs to
351 ShenandoahHeapRegion* humongous_start_region() const;
352
353 void set_new_top(HeapWord* new_top) { _new_top = new_top; }
354 HeapWord* new_top() const { return _new_top; }
355
356 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
357 void reset_alloc_metadata_to_shared();
358 void reset_alloc_metadata();
359 size_t get_shared_allocs() const;
360 size_t get_tlab_allocs() const;
361 size_t get_gclab_allocs() const;
362
363 private:
364 void do_commit();
365 void do_uncommit();
366
367 inline void internal_increase_live_data(size_t s);
368 };
369
370 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP