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_stw_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   void record_pin();
 199   void record_unpin();
 200   size_t pin_count() const;
 201 
 202 private:
 203   static size_t RegionCount;
 204   static size_t RegionSizeBytes;
 205   static size_t RegionSizeWords;
 206   static size_t RegionSizeBytesShift;
 207   static size_t RegionSizeWordsShift;
 208   static size_t RegionSizeBytesMask;
 209   static size_t RegionSizeWordsMask;
 210   static size_t HumongousThresholdBytes;
 211   static size_t HumongousThresholdWords;
 212   static size_t MaxTLABSizeBytes;
 213   static size_t MaxTLABSizeWords;
 214 
 215   // Global allocation counter, increased for each allocation under Shenandoah heap lock.
 216   // Padded to avoid false sharing with the read-only fields above.
 217   struct PaddedAllocSeqNum {
 218     char _pad0[DEFAULT_CACHE_LINE_SIZE];
 219     uint64_t value;
 220     char _pad1[DEFAULT_CACHE_LINE_SIZE];
 221 
 222     PaddedAllocSeqNum() {
 223       // start with 1, reserve 0 for uninitialized value
 224       value = 1;
 225     }
 226   };
 227 
 228   static PaddedAllocSeqNum _alloc_seq_num;
 229 
 230   // Never updated fields
 231   ShenandoahHeap* _heap;
 232   MemRegion _reserved;
 233   size_t _region_number;
 234 
 235   // Rarely updated fields
 236   HeapWord* _new_top;
 237   double _empty_time;
 238 
 239   // Seldom updated fields
 240   RegionState _state;
 241 
 242   // Frequently updated fields
 243   size_t _tlab_allocs;
 244   size_t _gclab_allocs;
 245   size_t _shared_allocs;
 246 
 247   uint64_t _seqnum_first_alloc_mutator;
 248   uint64_t _seqnum_first_alloc_gc;
 249   uint64_t _seqnum_last_alloc_mutator;
 250   uint64_t _seqnum_last_alloc_gc;
 251 
 252   volatile jint _live_data;
 253   volatile jint _critical_pins;
 254 
 255   // Claim some space at the end to protect next region
 256   char _pad0[DEFAULT_CACHE_LINE_SIZE];
 257 
 258 public:
 259   ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start, size_t size_words, size_t index, bool committed);
 260 
 261   static const size_t MIN_NUM_REGIONS = 10;
 262 
 263   static void setup_sizes(size_t max_heap_size);
 264 
 265   double empty_time() {
 266     return _empty_time;
 267   }
 268 
 269   inline static size_t required_regions(size_t bytes) {
 270     return (bytes + ShenandoahHeapRegion::region_size_bytes() - 1) >> ShenandoahHeapRegion::region_size_bytes_shift();
 271   }
 272 
 273   inline static size_t region_count() {
 274     return ShenandoahHeapRegion::RegionCount;
 275   }
 276 
 277   inline static size_t region_size_bytes() {
 278     return ShenandoahHeapRegion::RegionSizeBytes;
 279   }
 280 
 281   inline static size_t region_size_words() {
 282     return ShenandoahHeapRegion::RegionSizeWords;
 283   }
 284 
 285   inline static size_t region_size_bytes_shift() {
 286     return ShenandoahHeapRegion::RegionSizeBytesShift;
 287   }
 288 
 289   inline static size_t region_size_words_shift() {
 290     return ShenandoahHeapRegion::RegionSizeWordsShift;
 291   }
 292 
 293   inline static size_t region_size_bytes_mask() {
 294     return ShenandoahHeapRegion::RegionSizeBytesMask;
 295   }
 296 
 297   inline static size_t region_size_words_mask() {
 298     return ShenandoahHeapRegion::RegionSizeWordsMask;
 299   }
 300 
 301   // Convert to jint with sanity checking
 302   inline static jint region_size_bytes_jint() {
 303     assert (ShenandoahHeapRegion::RegionSizeBytes <= (size_t)max_jint, "sanity");
 304     return (jint)ShenandoahHeapRegion::RegionSizeBytes;
 305   }
 306 
 307   // Convert to jint with sanity checking
 308   inline static jint region_size_words_jint() {
 309     assert (ShenandoahHeapRegion::RegionSizeWords <= (size_t)max_jint, "sanity");
 310     return (jint)ShenandoahHeapRegion::RegionSizeWords;
 311   }
 312 
 313   // Convert to jint with sanity checking
 314   inline static jint region_size_bytes_shift_jint() {
 315     assert (ShenandoahHeapRegion::RegionSizeBytesShift <= (size_t)max_jint, "sanity");
 316     return (jint)ShenandoahHeapRegion::RegionSizeBytesShift;
 317   }
 318 
 319   // Convert to jint with sanity checking
 320   inline static jint region_size_words_shift_jint() {
 321     assert (ShenandoahHeapRegion::RegionSizeWordsShift <= (size_t)max_jint, "sanity");
 322     return (jint)ShenandoahHeapRegion::RegionSizeWordsShift;
 323   }
 324 
 325   inline static size_t humongous_threshold_bytes() {
 326     return ShenandoahHeapRegion::HumongousThresholdBytes;
 327   }
 328 
 329   inline static size_t humongous_threshold_words() {
 330     return ShenandoahHeapRegion::HumongousThresholdWords;
 331   }
 332 
 333   inline static size_t max_tlab_size_bytes() {
 334     return ShenandoahHeapRegion::MaxTLABSizeBytes;
 335   }
 336 
 337   inline static size_t max_tlab_size_words() {
 338     return ShenandoahHeapRegion::MaxTLABSizeWords;
 339   }
 340 
 341   static uint64_t seqnum_current_alloc() {
 342     // Last used seq number
 343     return _alloc_seq_num.value - 1;
 344   }
 345 
 346   size_t region_number() const;
 347 
 348   // Allocation (return NULL if full)
 349   inline HeapWord* allocate(size_t word_size, ShenandoahAllocRequest::Type type);
 350 
 351   HeapWord* allocate(size_t word_size) shenandoah_not_implemented_return(NULL)
 352 
 353   void clear_live_data();
 354   void set_live_data(size_t s);
 355 
 356   // Increase live data for newly allocated region
 357   inline void increase_live_data_alloc_words(size_t s);
 358 
 359   // Increase live data for region scanned with GC
 360   inline void increase_live_data_gc_words(size_t s);
 361 
 362   bool has_live() const;
 363   size_t get_live_data_bytes() const;
 364   size_t get_live_data_words() const;
 365 
 366   void print_on(outputStream* st) const;
 367 
 368   size_t garbage() const;
 369 
 370   void recycle();
 371 
 372   void oop_iterate_skip_unreachable(ExtendedOopClosure* cl, bool skip_unreachable_objects) shenandoah_not_implemented;
 373   HeapWord* object_iterate_careful(ObjectClosureCareful* cl) shenandoah_not_implemented_return(NULL);
 374 
 375   HeapWord* block_start_const(const void* p) const;
 376 
 377   bool in_collection_set() const;
 378 
 379   // Find humongous start region that this region belongs to
 380   ShenandoahHeapRegion* humongous_start_region() const;
 381 
 382   void set_new_top(HeapWord* new_top) { _new_top = new_top; }
 383   HeapWord* new_top() const { return _new_top; }
 384 
 385   inline void adjust_alloc_metadata(ShenandoahAllocRequest::Type type, size_t);
 386   void reset_alloc_metadata_to_shared();
 387   void reset_alloc_metadata();
 388   size_t get_shared_allocs() const;
 389   size_t get_tlab_allocs() const;
 390   size_t get_gclab_allocs() const;
 391 
 392   uint64_t seqnum_first_alloc() const {
 393     if (_seqnum_first_alloc_mutator == 0) return _seqnum_first_alloc_gc;
 394     if (_seqnum_first_alloc_gc == 0)      return _seqnum_first_alloc_mutator;
 395     return MIN2(_seqnum_first_alloc_mutator, _seqnum_first_alloc_gc);
 396   }
 397 
 398   uint64_t seqnum_last_alloc() const {
 399     return MAX2(_seqnum_last_alloc_mutator, _seqnum_last_alloc_gc);
 400   }
 401 
 402   uint64_t seqnum_first_alloc_mutator() const {
 403     return _seqnum_first_alloc_mutator;
 404   }
 405 
 406   uint64_t seqnum_last_alloc_mutator()  const {
 407     return _seqnum_last_alloc_mutator;
 408   }
 409 
 410   uint64_t seqnum_first_alloc_gc() const {
 411     return _seqnum_first_alloc_gc;
 412   }
 413 
 414   uint64_t seqnum_last_alloc_gc()  const {
 415     return _seqnum_last_alloc_gc;
 416   }
 417 
 418 private:
 419   void do_commit();
 420   void do_uncommit();
 421 
 422   inline void internal_increase_live_data(size_t s);
 423 };
 424 
 425 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAPREGION_HPP