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