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_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP 25 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP 26 27 #include "gc/shared/space.hpp" 28 #include "gc/shenandoah/shenandoahAllocRequest.hpp" 29 #include "gc/shenandoah/shenandoahAsserts.hpp" 30 #include "gc/shenandoah/shenandoahHeap.hpp" 31 #include "gc/shenandoah/shenandoahPacer.hpp" 32 #include "memory/universe.hpp" 33 #include "utilities/sizes.hpp" 34 35 class VMStructs; 36 class ShenandoahHeapRegionStateConstant; 37 38 class ShenandoahHeapRegion : public ContiguousSpace { 39 friend class VMStructs; 40 friend class ShenandoahHeapRegionStateConstant; 41 private: 42 /* 43 Region state is described by a state machine. Transitions are guarded by 44 heap lock, which allows changing the state of several regions atomically. 45 Region states can be logically aggregated in groups. 46 47 "Empty": 48 ................................................................. 49 . . 50 . . 51 . Uncommitted <------- Committed <------------------------\ 52 . | | . | 53 . \---------v-----------/ . | 54 . | . | 55 .........................|....................................... | 56 | | 57 "Active": | | 58 .........................|....................................... | 59 . | . | 60 . /-----------------^-------------------\ . | 61 . | | . | 62 . v v "Humongous": . | 63 . Regular ---\-----\ ..................O................ . | 64 . | ^ | | . | . . | 65 . | | | | . *---------\ . . | 66 . v | | | . v v . . | 67 . Pinned Cset | . HStart <--> H/Start H/Cont . . | 68 . ^ / | | . Pinned v | . . | 69 . | / | | . *<--------/ . . | 70 . | v | | . | . . | 71 . CsetPinned | | ..................O................ . | 72 . | | | . | 73 . \-----\---v-------------------/ . | 74 . | . | 75 .........................|....................................... | 76 | | 77 "Trash": | | 78 .........................|....................................... | 79 . | . | 80 . v . | 81 . Trash ---------------------------------------/ 82 . . 83 . . 84 ................................................................. 85 86 Transition from "Empty" to "Active" is first allocation. It can go from {Uncommitted, Committed} 87 to {Regular, "Humongous"}. The allocation may happen in Regular regions too, but not in Humongous. 88 89 Transition from "Active" to "Trash" is reclamation. It can go from CSet during the normal cycle, 90 and from {Regular, "Humongous"} for immediate reclamation. The existence of Trash state allows 91 quick reclamation without actual cleaning up. 92 93 Transition from "Trash" to "Empty" is recycling. It cleans up the regions and corresponding metadata. 94 Can be done asynchronously and in bulk. 95 96 Note how internal transitions disallow logic bugs: 97 a) No region can go Empty, unless properly reclaimed/recycled; 98 b) No region can go Uncommitted, unless reclaimed/recycled first; 99 c) Only Regular regions can go to CSet; 100 d) Pinned cannot go Trash, thus it could never be reclaimed until unpinned; 101 e) Pinned cannot go CSet, thus it never moves; 102 f) Humongous cannot be used for regular allocations; 103 g) Humongous cannot go CSet, thus it never moves; 104 h) Humongous start can go pinned, and thus can be protected from moves (humongous continuations should 105 follow associated humongous starts, not pinnable/movable by themselves); 106 i) Empty cannot go Trash, avoiding useless work; 107 j) ... 108 */ 109 110 enum RegionState { 111 _empty_uncommitted, // region is empty and has memory uncommitted 112 _empty_committed, // region is empty and has memory committed 113 _regular, // region is for regular allocations 114 _humongous_start, // region is the humongous start 115 _humongous_cont, // region is the humongous continuation 116 _pinned_humongous_start, // region is both humongous start and pinned 117 _cset, // region is in collection set 118 _pinned, // region is pinned 119 _pinned_cset, // region is pinned and in cset (evac failure path) 120 _trash, // region contains only trash 121 _REGION_STATES_NUM, // last 122 }; 123 124 static const char* region_state_to_string(RegionState s) { 125 switch (s) { 126 case _empty_uncommitted: return "Empty Uncommitted"; 127 case _empty_committed: return "Empty Committed"; 128 case _regular: return "Regular"; 129 case _humongous_start: return "Humongous Start"; 130 case _humongous_cont: return "Humongous Continuation"; 131 case _pinned_humongous_start: return "Humongous Start, Pinned"; 132 case _cset: return "Collection Set"; 133 case _pinned: return "Pinned"; 134 case _pinned_cset: return "Collection Set, Pinned"; 135 case _trash: return "Trash"; 136 default: 137 ShouldNotReachHere(); 138 return ""; 139 } 140 } 141 142 // This method protects from accidental changes in enum order: 143 int region_state_to_ordinal(RegionState s) const { 144 switch (s) { 145 case _empty_uncommitted: return 0; 146 case _empty_committed: return 1; 147 case _regular: return 2; 148 case _humongous_start: return 3; 149 case _humongous_cont: return 4; 150 case _cset: return 5; 151 case _pinned: return 6; 152 case _trash: return 7; 153 case _pinned_cset: return 8; 154 case _pinned_humongous_start: return 9; 155 default: 156 ShouldNotReachHere(); 157 return -1; 158 } 159 } 160 161 void report_illegal_transition(const char* method); 162 163 public: 164 static const int region_states_num() { 165 return _REGION_STATES_NUM; 166 } 167 168 // Allowed transitions from the outside code: 169 void make_regular_allocation(); 170 void make_regular_bypass(); 171 void make_humongous_start(); 172 void make_humongous_cont(); 173 void make_humongous_start_bypass(); 174 void make_humongous_cont_bypass(); 175 void make_pinned(); 176 void make_unpinned(); 177 void make_cset(); 178 void make_trash(); 179 void make_trash_immediate(); 180 void make_empty(); 181 void make_uncommitted(); 182 void make_committed_bypass(); 183 184 // Individual states: 185 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; } 186 bool is_empty_committed() const { return _state == _empty_committed; } 187 bool is_regular() const { return _state == _regular; } 188 bool is_humongous_continuation() const { return _state == _humongous_cont; } 189 190 // Participation in logical groups: 191 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); } 192 bool is_active() const { return !is_empty() && !is_trash(); } 193 bool is_trash() const { return _state == _trash; } 194 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; } 195 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); } 196 bool is_committed() const { return !is_empty_uncommitted(); } 197 bool is_cset() const { return _state == _cset || _state == _pinned_cset; } 198 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; } 199 200 // Macro-properties: 201 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; } 202 bool is_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); } 203 204 RegionState state() const { return _state; } 205 int state_ordinal() const { return region_state_to_ordinal(_state); } 206 207 private: 208 static size_t RegionCount; 209 static size_t RegionSizeBytes; 210 static size_t RegionSizeWords; 211 static size_t RegionSizeBytesShift; 212 static size_t RegionSizeWordsShift; 213 static size_t RegionSizeBytesMask; 214 static size_t RegionSizeWordsMask; 215 static size_t HumongousThresholdBytes; 216 static size_t HumongousThresholdWords; 217 static size_t MaxTLABSizeBytes; 218 static size_t MaxTLABSizeWords; 219 220 // Global allocation counter, increased for each allocation under Shenandoah heap lock. 221 // Padded to avoid false sharing with the read-only fields above. 222 struct PaddedAllocSeqNum { 223 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(uint64_t)); 224 uint64_t value; 225 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0); 226 227 PaddedAllocSeqNum() { 228 // start with 1, reserve 0 for uninitialized value 229 value = 1; 230 } 231 }; 232 233 static PaddedAllocSeqNum _alloc_seq_num; 234 235 // Never updated fields 236 ShenandoahHeap* _heap; 237 ShenandoahPacer* _pacer; 238 MemRegion _reserved; 239 size_t _region_number; 240 241 // Rarely updated fields 242 HeapWord* _new_top; 243 size_t _critical_pins; 244 double _empty_time; 245 246 // Seldom updated fields 247 RegionState _state; 248 249 // Frequently updated fields 250 size_t _tlab_allocs; 251 size_t _gclab_allocs; 252 size_t _shared_allocs; 253 254 uint64_t _seqnum_first_alloc_mutator; 255 uint64_t _seqnum_first_alloc_gc; 256 uint64_t _seqnum_last_alloc_mutator; 257 uint64_t _seqnum_last_alloc_gc; 258 259 volatile size_t _live_data; 260 261 // Claim some space at the end to protect next region 262 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0); 263 264 public: 265 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed); 266 267 static const size_t MIN_NUM_REGIONS = 10; 268 269 static void setup_sizes(size_t initial_heap_size, size_t max_heap_size); 270 271 double empty_time() { 272 return _empty_time; 273 } 274 275 inline static size_t required_regions(size_t bytes) { 276 return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift(); 277 } 278 279 inline static size_t region_count() { 280 return ShenandoahHeapRegion::RegionCount; 281 } 282 283 inline static size_t region_size_bytes() { 284 return ShenandoahHeapRegion::RegionSizeBytes; 285 } 286 287 inline static size_t region_size_words() { 288 return ShenandoahHeapRegion::RegionSizeWords; 289 } 290 291 inline static size_t region_size_bytes_shift() { 292 return ShenandoahHeapRegion::RegionSizeBytesShift; 293 } 294 295 inline static size_t region_size_words_shift() { 296 return ShenandoahHeapRegion::RegionSizeWordsShift; 297 } 298 299 inline static size_t region_size_bytes_mask() { 300 return ShenandoahHeapRegion::RegionSizeBytesMask; 301 } 302 303 inline static size_t region_size_words_mask() { 304 return ShenandoahHeapRegion::RegionSizeWordsMask; 305 } 306 307 // Convert to jint with sanity checking 308 inline static jint region_size_bytes_jint() { 309 assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity"); 310 return (jint)ShenandoahHeapRegion::RegionSizeBytes; 311 } 312 313 // Convert to jint with sanity checking 314 inline static jint region_size_words_jint() { 315 assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity"); 316 return (jint)ShenandoahHeapRegion::RegionSizeWords; 317 } 318 319 // Convert to jint with sanity checking 320 inline static jint region_size_bytes_shift_jint() { 321 assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity"); 322 return (jint)ShenandoahHeapRegion::RegionSizeBytesShift; 323 } 324 325 // Convert to jint with sanity checking 326 inline static jint region_size_words_shift_jint() { 327 assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity"); 328 return (jint)ShenandoahHeapRegion::RegionSizeWordsShift; 329 } 330 331 inline static size_t humongous_threshold_bytes() { 332 return ShenandoahHeapRegion::HumongousThresholdBytes; 333 } 334 335 inline static size_t humongous_threshold_words() { 336 return ShenandoahHeapRegion::HumongousThresholdWords; 337 } 338 339 inline static size_t max_tlab_size_bytes() { 340 return ShenandoahHeapRegion::MaxTLABSizeBytes; 341 } 342 343 inline static size_t max_tlab_size_words() { 344 return ShenandoahHeapRegion::MaxTLABSizeWords; 345 } 346 347 static uint64_t seqnum_current_alloc() { 348 // Last used seq number 349 return _alloc_seq_num.value - 1; 350 } 351 352 size_t region_number() const; 353 354 // Allocation (return NULL if full) 355 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type); 356 357 HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL) 358 359 void clear_live_data(); 360 void set_live_data(size_t s); 361 362 // Increase live data for newly allocated region 363 inline void increase_live_data_alloc_words(size_t s); 364 365 // Increase live data for region scanned with GC 366 inline void increase_live_data_gc_words(size_t s); 367 368 bool has_live() const; 369 size_t get_live_data_bytes() const; 370 size_t get_live_data_words() const; 371 372 void print_on(outputStream* st) const; 373 374 size_t garbage() const; 375 376 void recycle(); 377 378 void oop_iterate(OopIterateClosure* cl); 379 380 HeapWord* block_start_const(const void* p) const; 381 382 bool in_collection_set() const; 383 384 // Find humongous start region that this region belongs to 385 ShenandoahHeapRegion* humongous_start_region() const; 386 387 CompactibleSpace* next_compaction_space() const shenandoah_not_implemented_return(NULL); 388 void prepare_for_compaction(CompactPoint* cp) shenandoah_not_implemented; 389 void adjust_pointers() shenandoah_not_implemented; 390 void compact() shenandoah_not_implemented; 391 392 void set_new_top(HeapWord* new_top) { _new_top = new_top; } 393 HeapWord* new_top() const { return _new_top; } 394 395 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t); 396 void reset_alloc_metadata_to_shared(); 397 void reset_alloc_metadata(); 398 size_t get_shared_allocs() const; 399 size_t get_tlab_allocs() const; 400 size_t get_gclab_allocs() const; 401 402 uint64_t seqnum_first_alloc() const { 403 if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc; 404 if (_seqnum_first_alloc_gc == 0) return _seqnum_first_alloc_mutator; 405 return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc); 406 } 407 408 uint64_t seqnum_last_alloc() const { 409 return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc); 410 } 411 412 uint64_t seqnum_first_alloc_mutator() const { 413 return _seqnum_first_alloc_mutator; 414 } 415 416 uint64_t seqnum_last_alloc_mutator() const { 417 return _seqnum_last_alloc_mutator; 418 } 419 420 uint64_t seqnum_first_alloc_gc() const { 421 return _seqnum_first_alloc_gc; 422 } 423 424 uint64_t seqnum_last_alloc_gc() const { 425 return _seqnum_last_alloc_gc; 426 } 427 428 private: 429 void do_commit(); 430 void do_uncommit(); 431 432 void oop_iterate_objects(OopIterateClosure* cl); 433 void oop_iterate_humongous(OopIterateClosure* cl); 434 435 inline void internal_increase_live_data(size_t s); 436 437 void set_state(RegionState to); 438 }; 439 440 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP