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/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   MemRegion _reserved;
 238   size_t _region_number;
 239 
 240   // Rarely updated fields
 241   HeapWord* _new_top;
 242   size_t _critical_pins;
 243   double _empty_time;
 244 
 245   // Seldom updated fields
 246   RegionState _state;
 247 
 248   // Frequently updated fields
 249   size_t _tlab_allocs;
 250   size_t _gclab_allocs;
 251   size_t _shared_allocs;
 252 
 253   uint64_t _seqnum_first_alloc_mutator;
 254   uint64_t _seqnum_first_alloc_gc;
 255   uint64_t _seqnum_last_alloc_mutator;
 256   uint64_t _seqnum_last_alloc_gc;
 257 
 258   volatile size_t _live_data;
 259 
 260   // Claim some space at the end to protect next region
 261   DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
 262 
 263 public:
 264   ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
 265 
 266   static const size_t MIN_NUM_REGIONS = 10;
 267 
 268   static void setup_sizes(size_t max_heap_size);
 269 
 270   double empty_time() {
 271     return _empty_time;
 272   }
 273 
 274   inline static size_t required_regions(size_t bytes) {
 275     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
 276   }
 277 
 278   inline static size_t region_count() {
 279     return ShenandoahHeapRegion::RegionCount;
 280   }
 281 
 282   inline static size_t region_size_bytes() {
 283     return ShenandoahHeapRegion::RegionSizeBytes;
 284   }
 285 
 286   inline static size_t region_size_words() {
 287     return ShenandoahHeapRegion::RegionSizeWords;
 288   }
 289 
 290   inline static size_t region_size_bytes_shift() {
 291     return ShenandoahHeapRegion::RegionSizeBytesShift;
 292   }
 293 
 294   inline static size_t region_size_words_shift() {
 295     return ShenandoahHeapRegion::RegionSizeWordsShift;
 296   }
 297 
 298   inline static size_t region_size_bytes_mask() {
 299     return ShenandoahHeapRegion::RegionSizeBytesMask;
 300   }
 301 
 302   inline static size_t region_size_words_mask() {
 303     return ShenandoahHeapRegion::RegionSizeWordsMask;
 304   }
 305 
 306   // Convert to jint with sanity checking
 307   inline static jint region_size_bytes_jint() {
 308     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
 309     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
 310   }
 311 
 312   // Convert to jint with sanity checking
 313   inline static jint region_size_words_jint() {
 314     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
 315     return (jint)ShenandoahHeapRegion::RegionSizeWords;
 316   }
 317 
 318   // Convert to jint with sanity checking
 319   inline static jint region_size_bytes_shift_jint() {
 320     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
 321     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
 322   }
 323 
 324   // Convert to jint with sanity checking
 325   inline static jint region_size_words_shift_jint() {
 326     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
 327     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
 328   }
 329 
 330   inline static size_t humongous_threshold_bytes() {
 331     return ShenandoahHeapRegion::HumongousThresholdBytes;
 332   }
 333 
 334   inline static size_t humongous_threshold_words() {
 335     return ShenandoahHeapRegion::HumongousThresholdWords;
 336   }
 337 
 338   inline static size_t max_tlab_size_bytes() {
 339     return ShenandoahHeapRegion::MaxTLABSizeBytes;
 340   }
 341 
 342   inline static size_t max_tlab_size_words() {
 343     return ShenandoahHeapRegion::MaxTLABSizeWords;
 344   }
 345 
 346   static uint64_t seqnum_current_alloc() {
 347     // Last used seq number
 348     return _alloc_seq_num.value - 1;
 349   }
 350 
 351   size_t region_number() const;
 352 
 353   // Allocation (return NULL if full)
 354   inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
 355 
 356   HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL)
 357 
 358   void clear_live_data();
 359   void set_live_data(size_t s);
 360 
 361   // Increase live data for newly allocated region
 362   inline void increase_live_data_alloc_words(size_t s);
 363 
 364   // Increase live data for region scanned with GC
 365   inline void increase_live_data_gc_words(size_t s);
 366 
 367   bool has_live() const;
 368   size_t get_live_data_bytes() const;
 369   size_t get_live_data_words() const;
 370 
 371   void print_on(outputStream* st) const;
 372 
 373   size_t garbage() const;
 374 
 375   void recycle();
 376 
 377   void oop_iterate(OopIterateClosure* cl);
 378 
 379   HeapWord* block_start_const(const void* p) const;
 380 
 381   bool in_collection_set() const;
 382 
 383   // Find humongous start region that this region belongs to
 384   ShenandoahHeapRegion* humongous_start_region() const;
 385 
 386   CompactibleSpace* next_compaction_space() const shenandoah_not_implemented_return(NULL);
 387   void prepare_for_compaction(CompactPoint* cp)   shenandoah_not_implemented;
 388   void adjust_pointers()                          shenandoah_not_implemented;
 389   void compact()                                  shenandoah_not_implemented;
 390 
 391   void set_new_top(HeapWord* new_top) { _new_top = new_top; }
 392   HeapWord* new_top() const { return _new_top; }
 393 
 394   inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
 395   void reset_alloc_metadata_to_shared();
 396   void reset_alloc_metadata();
 397   size_t get_shared_allocs() const;
 398   size_t get_tlab_allocs() const;
 399   size_t get_gclab_allocs() const;
 400 
 401   uint64_t seqnum_first_alloc() const {
 402     if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc;
 403     if (_seqnum_first_alloc_gc == 0)      return _seqnum_first_alloc_mutator;
 404     return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc);
 405   }
 406 
 407   uint64_t seqnum_last_alloc() const {
 408     return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc);
 409   }
 410 
 411   uint64_t seqnum_first_alloc_mutator() const {
 412     return _seqnum_first_alloc_mutator;
 413   }
 414 
 415   uint64_t seqnum_last_alloc_mutator()  const {
 416     return _seqnum_last_alloc_mutator;
 417   }
 418 
 419   uint64_t seqnum_first_alloc_gc() const {
 420     return _seqnum_first_alloc_gc;
 421   }
 422 
 423   uint64_t seqnum_last_alloc_gc()  const {
 424     return _seqnum_last_alloc_gc;
 425   }
 426 
 427 private:
 428   void do_commit();
 429   void do_uncommit();
 430 
 431   void oop_iterate_objects(OopIterateClosure* cl);
 432   void oop_iterate_humongous(OopIterateClosure* cl);
 433 
 434   inline void internal_increase_live_data(size_t s);
 435 
 436   void set_state(RegionState to);
 437 };
 438 
 439 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP