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_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 37 class ShenandoahHeapRegion : public ContiguousSpace { 38 friend class VMStructs; 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 }; 120 121 const char* region_state_to_string(RegionState s) const { 122 switch (s) { 123 case _empty_uncommitted: return "Empty Uncommitted"; 124 case _empty_committed: return "Empty Committed"; 125 case _regular: return "Regular"; 126 case _humongous_start: return "Humongous Start"; 127 case _humongous_cont: return "Humongous Continuation"; 128 case _pinned_humongous_start: return "Humongous Start, Pinned"; 129 case _cset: return "Collection Set"; 130 case _pinned: return "Pinned"; 131 case _pinned_cset: return "Collection Set, Pinned"; 132 case _trash: return "Trash"; 133 default: 134 ShouldNotReachHere(); 135 return ""; 136 } 137 } 138 139 // This method protects from accidental changes in enum order: 140 int region_state_to_ordinal(RegionState s) const { 141 switch (s) { 142 case _empty_uncommitted: return 0; 143 case _empty_committed: return 1; 144 case _regular: return 2; 145 case _humongous_start: return 3; 146 case _humongous_cont: return 4; 147 case _cset: return 5; 148 case _pinned: return 6; 149 case _trash: return 7; 150 case _pinned_cset: return 8; 151 case _pinned_humongous_start: return 9; 152 default: 153 ShouldNotReachHere(); 154 return -1; 155 } 156 } 157 158 void report_illegal_transition(const char* method); 159 160 public: 161 // Allowed transitions from the outside code: 162 void make_regular_allocation(); 163 void make_regular_bypass(); 164 void make_humongous_start(); 165 void make_humongous_cont(); 166 void make_humongous_start_bypass(); 167 void make_humongous_cont_bypass(); 168 void make_pinned(); 169 void make_unpinned(); 170 void make_cset(); 171 void make_trash(); 172 void make_trash_immediate(); 173 void make_empty(); 174 void make_uncommitted(); 175 void make_committed_bypass(); 176 177 // Individual states: 178 bool is_empty_uncommitted() const { return _state == _empty_uncommitted; } 179 bool is_empty_committed() const { return _state == _empty_committed; } 180 bool is_regular() const { return _state == _regular; } 181 bool is_humongous_continuation() const { return _state == _humongous_cont; } 182 183 // Participation in logical groups: 184 bool is_empty() const { return is_empty_committed() || is_empty_uncommitted(); } 185 bool is_active() const { return !is_empty() && !is_trash(); } 186 bool is_trash() const { return _state == _trash; } 187 bool is_humongous_start() const { return _state == _humongous_start || _state == _pinned_humongous_start; } 188 bool is_humongous() const { return is_humongous_start() || is_humongous_continuation(); } 189 bool is_committed() const { return !is_empty_uncommitted(); } 190 bool is_cset() const { return _state == _cset || _state == _pinned_cset; } 191 bool is_pinned() const { return _state == _pinned || _state == _pinned_cset || _state == _pinned_humongous_start; } 192 193 // Macro-properties: 194 bool is_alloc_allowed() const { return is_empty() || is_regular() || _state == _pinned; } 195 bool is_move_allowed() const { return is_regular() || _state == _cset || (ShenandoahHumongousMoves && _state == _humongous_start); } 196 197 RegionState state() const { return _state; } 198 int state_ordinal() const { return region_state_to_ordinal(_state); } 199 200 private: 201 static size_t RegionCount; 202 static size_t RegionSizeBytes; 203 static size_t RegionSizeWords; 204 static size_t RegionSizeBytesShift; 205 static size_t RegionSizeWordsShift; 206 static size_t RegionSizeBytesMask; 207 static size_t RegionSizeWordsMask; 208 static size_t HumongousThresholdBytes; 209 static size_t HumongousThresholdWords; 210 static size_t MaxTLABSizeBytes; 211 static size_t MaxTLABSizeWords; 212 213 // Global allocation counter, increased for each allocation under Shenandoah heap lock. 214 // Padded to avoid false sharing with the read-only fields above. 215 struct PaddedAllocSeqNum { 216 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(uint64_t)); 217 uint64_t value; 218 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0); 219 220 PaddedAllocSeqNum() { 221 // start with 1, reserve 0 for uninitialized value 222 value = 1; 223 } 224 }; 225 226 static PaddedAllocSeqNum _alloc_seq_num; 227 228 // Never updated fields 229 ShenandoahHeap* _heap; 230 MemRegion _reserved; 231 size_t _region_number; 232 233 // Rarely updated fields 234 HeapWord* _new_top; 235 size_t _critical_pins; 236 double _empty_time; 237 238 // Seldom updated fields 239 RegionState _state; 240 241 // Frequently updated fields 242 size_t _tlab_allocs; 243 size_t _gclab_allocs; 244 size_t _shared_allocs; 245 246 uint64_t _seqnum_first_alloc_mutator; 247 uint64_t _seqnum_first_alloc_gc; 248 uint64_t _seqnum_last_alloc_mutator; 249 uint64_t _seqnum_last_alloc_gc; 250 251 volatile size_t _live_data; 252 253 // Claim some space at the end to protect next region 254 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0); 255 256 public: 257 ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed); 258 259 static const size_t MIN_NUM_REGIONS = 10; 260 261 static void setup_sizes(size_t initial_heap_size, 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 static uint64_t seqnum_current_alloc() { 340 // Last used seq number 341 return _alloc_seq_num.value - 1; 342 } 343 344 size_t region_number() const; 345 346 // Allocation (return NULL if full) 347 inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type); 348 349 HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL) 350 351 void clear_live_data(); 352 void set_live_data(size_t s); 353 354 // Increase live data for newly allocated region 355 inline void increase_live_data_alloc_words(size_t s); 356 357 // Increase live data for region scanned with GC 358 inline void increase_live_data_gc_words(size_t s); 359 360 bool has_live() const; 361 size_t get_live_data_bytes() const; 362 size_t get_live_data_words() const; 363 364 void print_on(outputStream* st) const; 365 366 size_t garbage() const; 367 368 void recycle(); 369 370 void oop_iterate(OopIterateClosure* cl); 371 372 HeapWord* block_start_const(const void* p) const; 373 374 bool in_collection_set() const; 375 376 // Find humongous start region that this region belongs to 377 ShenandoahHeapRegion* humongous_start_region() const; 378 379 CompactibleSpace* next_compaction_space() const shenandoah_not_implemented_return(NULL); 380 void prepare_for_compaction(CompactPoint* cp) shenandoah_not_implemented; 381 void adjust_pointers() shenandoah_not_implemented; 382 void compact() shenandoah_not_implemented; 383 384 void set_new_top(HeapWord* new_top) { _new_top = new_top; } 385 HeapWord* new_top() const { return _new_top; } 386 387 inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t); 388 void reset_alloc_metadata_to_shared(); 389 void reset_alloc_metadata(); 390 size_t get_shared_allocs() const; 391 size_t get_tlab_allocs() const; 392 size_t get_gclab_allocs() const; 393 394 uint64_t seqnum_first_alloc() const { 395 if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc; 396 if (_seqnum_first_alloc_gc == 0) return _seqnum_first_alloc_mutator; 397 return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc); 398 } 399 400 uint64_t seqnum_last_alloc() const { 401 return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc); 402 } 403 404 uint64_t seqnum_first_alloc_mutator() const { 405 return _seqnum_first_alloc_mutator; 406 } 407 408 uint64_t seqnum_last_alloc_mutator() const { 409 return _seqnum_last_alloc_mutator; 410 } 411 412 uint64_t seqnum_first_alloc_gc() const { 413 return _seqnum_first_alloc_gc; 414 } 415 416 uint64_t seqnum_last_alloc_gc() const { 417 return _seqnum_last_alloc_gc; 418 } 419 420 private: 421 void do_commit(); 422 void do_uncommit(); 423 424 void oop_iterate_objects(OopIterateClosure* cl); 425 void oop_iterate_humongous(OopIterateClosure* cl); 426 427 inline void internal_increase_live_data(size_t s); 428 }; 429 430 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP