1 /*
   2  * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1CardLiveData.inline.hpp"
  30 #include "gc/g1/heapRegionManager.inline.hpp"
  31 #include "gc/g1/heapRegionRemSet.hpp"
  32 #include "gc/shared/space.inline.hpp"
  33 #include "memory/allocation.hpp"
  34 #include "memory/padded.inline.hpp"
  35 #include "oops/oop.inline.hpp"
  36 #include "runtime/atomic.inline.hpp"
  37 #include "utilities/bitMap.inline.hpp"
  38 #include "utilities/globalDefinitions.hpp"
  39 #include "utilities/growableArray.hpp"
  40 
  41 class PerRegionTable: public CHeapObj<mtGC> {
  42   friend class OtherRegionsTable;
  43   friend class HeapRegionRemSetIterator;
  44 
  45   HeapRegion*     _hr;
  46   BitMap          _bm;
  47   jint            _occupied;
  48 
  49   // next pointer for free/allocated 'all' list
  50   PerRegionTable* _next;
  51 
  52   // prev pointer for the allocated 'all' list
  53   PerRegionTable* _prev;
  54 
  55   // next pointer in collision list
  56   PerRegionTable * _collision_list_next;
  57 
  58   // Global free list of PRTs
  59   static PerRegionTable* volatile _free_list;
  60 
  61 protected:
  62   // We need access in order to union things into the base table.
  63   BitMap* bm() { return &_bm; }
  64 
  65   void recount_occupied() {
  66     _occupied = (jint) bm()->count_one_bits();
  67   }
  68 
  69   PerRegionTable(HeapRegion* hr) :
  70     _hr(hr),
  71     _occupied(0),
  72     _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
  73     _collision_list_next(NULL), _next(NULL), _prev(NULL)
  74   {}
  75 
  76   void add_card_work(CardIdx_t from_card, bool par) {
  77     if (!_bm.at(from_card)) {
  78       if (par) {
  79         if (_bm.par_at_put(from_card, 1)) {
  80           Atomic::inc(&_occupied);
  81         }
  82       } else {
  83         _bm.at_put(from_card, 1);
  84         _occupied++;
  85       }
  86     }
  87   }
  88 
  89   void add_reference_work(OopOrNarrowOopStar from, bool par) {
  90     // Must make this robust in case "from" is not in "_hr", because of
  91     // concurrency.
  92 
  93     HeapRegion* loc_hr = hr();
  94     // If the test below fails, then this table was reused concurrently
  95     // with this operation.  This is OK, since the old table was coarsened,
  96     // and adding a bit to the new table is never incorrect.
  97     // If the table used to belong to a continues humongous region and is
  98     // now reused for the corresponding start humongous region, we need to
  99     // make sure that we detect this. Thus, we call is_in_reserved_raw()
 100     // instead of just is_in_reserved() here.
 101     if (loc_hr->is_in_reserved(from)) {
 102       size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
 103       CardIdx_t from_card = (CardIdx_t)
 104           hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
 105 
 106       assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
 107              "Must be in range.");
 108       add_card_work(from_card, par);
 109     }
 110   }
 111 
 112 public:
 113 
 114   HeapRegion* hr() const {
 115     return (HeapRegion*) OrderAccess::load_ptr_acquire(&_hr);
 116   }
 117 
 118   jint occupied() const {
 119     // Overkill, but if we ever need it...
 120     // guarantee(_occupied == _bm.count_one_bits(), "Check");
 121     return _occupied;
 122   }
 123 
 124   void init(HeapRegion* hr, bool clear_links_to_all_list) {
 125     if (clear_links_to_all_list) {
 126       set_next(NULL);
 127       set_prev(NULL);
 128     }
 129     _collision_list_next = NULL;
 130     _occupied = 0;
 131     _bm.clear();
 132     // Make sure that the bitmap clearing above has been finished before publishing
 133     // this PRT to concurrent threads.
 134     OrderAccess::release_store_ptr(&_hr, hr);
 135   }
 136 
 137   void add_reference(OopOrNarrowOopStar from) {
 138     add_reference_work(from, /*parallel*/ true);
 139   }
 140 
 141   void seq_add_reference(OopOrNarrowOopStar from) {
 142     add_reference_work(from, /*parallel*/ false);
 143   }
 144 
 145   void scrub(G1CardLiveData* live_data) {
 146     live_data->remove_nonlive_cards(hr()->hrm_index(), &_bm);
 147     recount_occupied();
 148   }
 149 
 150   void add_card(CardIdx_t from_card_index) {
 151     add_card_work(from_card_index, /*parallel*/ true);
 152   }
 153 
 154   void seq_add_card(CardIdx_t from_card_index) {
 155     add_card_work(from_card_index, /*parallel*/ false);
 156   }
 157 
 158   // (Destructively) union the bitmap of the current table into the given
 159   // bitmap (which is assumed to be of the same size.)
 160   void union_bitmap_into(BitMap* bm) {
 161     bm->set_union(_bm);
 162   }
 163 
 164   // Mem size in bytes.
 165   size_t mem_size() const {
 166     return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
 167   }
 168 
 169   // Requires "from" to be in "hr()".
 170   bool contains_reference(OopOrNarrowOopStar from) const {
 171     assert(hr()->is_in_reserved(from), "Precondition.");
 172     size_t card_ind = pointer_delta(from, hr()->bottom(),
 173                                     CardTableModRefBS::card_size);
 174     return _bm.at(card_ind);
 175   }
 176 
 177   // Bulk-free the PRTs from prt to last, assumes that they are
 178   // linked together using their _next field.
 179   static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
 180     while (true) {
 181       PerRegionTable* fl = _free_list;
 182       last->set_next(fl);
 183       PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
 184       if (res == fl) {
 185         return;
 186       }
 187     }
 188     ShouldNotReachHere();
 189   }
 190 
 191   static void free(PerRegionTable* prt) {
 192     bulk_free(prt, prt);
 193   }
 194 
 195   // Returns an initialized PerRegionTable instance.
 196   static PerRegionTable* alloc(HeapRegion* hr) {
 197     PerRegionTable* fl = _free_list;
 198     while (fl != NULL) {
 199       PerRegionTable* nxt = fl->next();
 200       PerRegionTable* res =
 201         (PerRegionTable*)
 202         Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
 203       if (res == fl) {
 204         fl->init(hr, true);
 205         return fl;
 206       } else {
 207         fl = _free_list;
 208       }
 209     }
 210     assert(fl == NULL, "Loop condition.");
 211     return new PerRegionTable(hr);
 212   }
 213 
 214   PerRegionTable* next() const { return _next; }
 215   void set_next(PerRegionTable* next) { _next = next; }
 216   PerRegionTable* prev() const { return _prev; }
 217   void set_prev(PerRegionTable* prev) { _prev = prev; }
 218 
 219   // Accessor and Modification routines for the pointer for the
 220   // singly linked collision list that links the PRTs within the
 221   // OtherRegionsTable::_fine_grain_regions hash table.
 222   //
 223   // It might be useful to also make the collision list doubly linked
 224   // to avoid iteration over the collisions list during scrubbing/deletion.
 225   // OTOH there might not be many collisions.
 226 
 227   PerRegionTable* collision_list_next() const {
 228     return _collision_list_next;
 229   }
 230 
 231   void set_collision_list_next(PerRegionTable* next) {
 232     _collision_list_next = next;
 233   }
 234 
 235   PerRegionTable** collision_list_next_addr() {
 236     return &_collision_list_next;
 237   }
 238 
 239   static size_t fl_mem_size() {
 240     PerRegionTable* cur = _free_list;
 241     size_t res = 0;
 242     while (cur != NULL) {
 243       res += cur->mem_size();
 244       cur = cur->next();
 245     }
 246     return res;
 247   }
 248 
 249   static void test_fl_mem_size();
 250 };
 251 
 252 PerRegionTable* volatile PerRegionTable::_free_list = NULL;
 253 
 254 size_t OtherRegionsTable::_max_fine_entries = 0;
 255 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
 256 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 257 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 258 
 259 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
 260   _g1h(G1CollectedHeap::heap()),
 261   _hr(hr), _m(m),
 262   _coarse_map(G1CollectedHeap::heap()->max_regions(),
 263               false /* in-resource-area */),
 264   _fine_grain_regions(NULL),
 265   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
 266   _n_fine_entries(0), _n_coarse_entries(0),
 267   _fine_eviction_start(0),
 268   _sparse_table(hr)
 269 {
 270   typedef PerRegionTable* PerRegionTablePtr;
 271 
 272   if (_max_fine_entries == 0) {
 273     assert(_mod_max_fine_entries_mask == 0, "Both or none.");
 274     size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
 275     _max_fine_entries = (size_t)1 << max_entries_log;
 276     _mod_max_fine_entries_mask = _max_fine_entries - 1;
 277 
 278     assert(_fine_eviction_sample_size == 0
 279            && _fine_eviction_stride == 0, "All init at same time.");
 280     _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
 281     _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
 282   }
 283 
 284   _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
 285                         mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 286 
 287   if (_fine_grain_regions == NULL) {
 288     vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
 289                           "Failed to allocate _fine_grain_entries.");
 290   }
 291 
 292   for (size_t i = 0; i < _max_fine_entries; i++) {
 293     _fine_grain_regions[i] = NULL;
 294   }
 295 }
 296 
 297 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
 298   // We always append to the beginning of the list for convenience;
 299   // the order of entries in this list does not matter.
 300   if (_first_all_fine_prts != NULL) {
 301     assert(_first_all_fine_prts->prev() == NULL, "invariant");
 302     _first_all_fine_prts->set_prev(prt);
 303     prt->set_next(_first_all_fine_prts);
 304   } else {
 305     // this is the first element we insert. Adjust the "last" pointer
 306     _last_all_fine_prts = prt;
 307     assert(prt->next() == NULL, "just checking");
 308   }
 309   // the new element is always the first element without a predecessor
 310   prt->set_prev(NULL);
 311   _first_all_fine_prts = prt;
 312 
 313   assert(prt->prev() == NULL, "just checking");
 314   assert(_first_all_fine_prts == prt, "just checking");
 315   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 316          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 317          "just checking");
 318   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 319          "just checking");
 320   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 321          "just checking");
 322 }
 323 
 324 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
 325   if (prt->prev() != NULL) {
 326     assert(_first_all_fine_prts != prt, "just checking");
 327     prt->prev()->set_next(prt->next());
 328     // removing the last element in the list?
 329     if (_last_all_fine_prts == prt) {
 330       _last_all_fine_prts = prt->prev();
 331     }
 332   } else {
 333     assert(_first_all_fine_prts == prt, "just checking");
 334     _first_all_fine_prts = prt->next();
 335     // list is empty now?
 336     if (_first_all_fine_prts == NULL) {
 337       _last_all_fine_prts = NULL;
 338     }
 339   }
 340 
 341   if (prt->next() != NULL) {
 342     prt->next()->set_prev(prt->prev());
 343   }
 344 
 345   prt->set_next(NULL);
 346   prt->set_prev(NULL);
 347 
 348   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 349          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 350          "just checking");
 351   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 352          "just checking");
 353   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 354          "just checking");
 355 }
 356 
 357 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
 358   uint cur_hrm_ind = _hr->hrm_index();
 359 
 360   int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
 361 
 362   if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
 363     assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
 364     return;
 365   }
 366 
 367   // Note that this may be a continued H region.
 368   HeapRegion* from_hr = _g1h->heap_region_containing(from);
 369   RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
 370 
 371   // If the region is already coarsened, return.
 372   if (_coarse_map.at(from_hrm_ind)) {
 373     assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
 374     return;
 375   }
 376 
 377   // Otherwise find a per-region table to add it to.
 378   size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
 379   PerRegionTable* prt = find_region_table(ind, from_hr);
 380   if (prt == NULL) {
 381     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
 382     // Confirm that it's really not there...
 383     prt = find_region_table(ind, from_hr);
 384     if (prt == NULL) {
 385 
 386       uintptr_t from_hr_bot_card_index =
 387         uintptr_t(from_hr->bottom())
 388           >> CardTableModRefBS::card_shift;
 389       CardIdx_t card_index = from_card - from_hr_bot_card_index;
 390       assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 391              "Must be in range.");
 392       if (G1HRRSUseSparseTable &&
 393           _sparse_table.add_card(from_hrm_ind, card_index)) {
 394         assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
 395         return;
 396       }
 397 
 398       if (_n_fine_entries == _max_fine_entries) {
 399         prt = delete_region_table();
 400         // There is no need to clear the links to the 'all' list here:
 401         // prt will be reused immediately, i.e. remain in the 'all' list.
 402         prt->init(from_hr, false /* clear_links_to_all_list */);
 403       } else {
 404         prt = PerRegionTable::alloc(from_hr);
 405         link_to_all(prt);
 406       }
 407 
 408       PerRegionTable* first_prt = _fine_grain_regions[ind];
 409       prt->set_collision_list_next(first_prt);
 410       // The assignment into _fine_grain_regions allows the prt to
 411       // start being used concurrently. In addition to
 412       // collision_list_next which must be visible (else concurrent
 413       // parsing of the list, if any, may fail to see other entries),
 414       // the content of the prt must be visible (else for instance
 415       // some mark bits may not yet seem cleared or a 'later' update
 416       // performed by a concurrent thread could be undone when the
 417       // zeroing becomes visible). This requires store ordering.
 418       OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
 419       _n_fine_entries++;
 420 
 421       if (G1HRRSUseSparseTable) {
 422         // Transfer from sparse to fine-grain.
 423         SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
 424         assert(sprt_entry != NULL, "There should have been an entry");
 425         for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
 426           CardIdx_t c = sprt_entry->card(i);
 427           if (c != SparsePRTEntry::NullEntry) {
 428             prt->add_card(c);
 429           }
 430         }
 431         // Now we can delete the sparse entry.
 432         bool res = _sparse_table.delete_entry(from_hrm_ind);
 433         assert(res, "It should have been there.");
 434       }
 435     }
 436     assert(prt != NULL && prt->hr() == from_hr, "consequence");
 437   }
 438   // Note that we can't assert "prt->hr() == from_hr", because of the
 439   // possibility of concurrent reuse.  But see head comment of
 440   // OtherRegionsTable for why this is OK.
 441   assert(prt != NULL, "Inv");
 442 
 443   prt->add_reference(from);
 444   assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT", p2i(from));
 445 }
 446 
 447 PerRegionTable*
 448 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
 449   assert(ind < _max_fine_entries, "Preconditions.");
 450   PerRegionTable* prt = _fine_grain_regions[ind];
 451   while (prt != NULL && prt->hr() != hr) {
 452     prt = prt->collision_list_next();
 453   }
 454   // Loop postcondition is the method postcondition.
 455   return prt;
 456 }
 457 
 458 jint OtherRegionsTable::_n_coarsenings = 0;
 459 
 460 PerRegionTable* OtherRegionsTable::delete_region_table() {
 461   assert(_m->owned_by_self(), "Precondition");
 462   assert(_n_fine_entries == _max_fine_entries, "Precondition");
 463   PerRegionTable* max = NULL;
 464   jint max_occ = 0;
 465   PerRegionTable** max_prev = NULL;
 466   size_t max_ind;
 467 
 468   size_t i = _fine_eviction_start;
 469   for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
 470     size_t ii = i;
 471     // Make sure we get a non-NULL sample.
 472     while (_fine_grain_regions[ii] == NULL) {
 473       ii++;
 474       if (ii == _max_fine_entries) ii = 0;
 475       guarantee(ii != i, "We must find one.");
 476     }
 477     PerRegionTable** prev = &_fine_grain_regions[ii];
 478     PerRegionTable* cur = *prev;
 479     while (cur != NULL) {
 480       jint cur_occ = cur->occupied();
 481       if (max == NULL || cur_occ > max_occ) {
 482         max = cur;
 483         max_prev = prev;
 484         max_ind = i;
 485         max_occ = cur_occ;
 486       }
 487       prev = cur->collision_list_next_addr();
 488       cur = cur->collision_list_next();
 489     }
 490     i = i + _fine_eviction_stride;
 491     if (i >= _n_fine_entries) i = i - _n_fine_entries;
 492   }
 493 
 494   _fine_eviction_start++;
 495 
 496   if (_fine_eviction_start >= _n_fine_entries) {
 497     _fine_eviction_start -= _n_fine_entries;
 498   }
 499 
 500   guarantee(max != NULL, "Since _n_fine_entries > 0");
 501   guarantee(max_prev != NULL, "Since max != NULL.");
 502 
 503   // Set the corresponding coarse bit.
 504   size_t max_hrm_index = (size_t) max->hr()->hrm_index();
 505   if (!_coarse_map.at(max_hrm_index)) {
 506     _coarse_map.at_put(max_hrm_index, true);
 507     _n_coarse_entries++;
 508   }
 509 
 510   // Unsplice.
 511   *max_prev = max->collision_list_next();
 512   Atomic::inc(&_n_coarsenings);
 513   _n_fine_entries--;
 514   return max;
 515 }
 516 
 517 void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
 518   // First eliminated garbage regions from the coarse map.
 519   log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
 520 
 521   log_develop_trace(gc, remset, scrub)("   Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
 522   live_data->remove_nonlive_regions(&_coarse_map);
 523   _n_coarse_entries = _coarse_map.count_one_bits();
 524   log_develop_trace(gc, remset, scrub)("   after = " SIZE_FORMAT ".", _n_coarse_entries);
 525 
 526   // Now do the fine-grained maps.
 527   for (size_t i = 0; i < _max_fine_entries; i++) {
 528     PerRegionTable* cur = _fine_grain_regions[i];
 529     PerRegionTable** prev = &_fine_grain_regions[i];
 530     while (cur != NULL) {
 531       PerRegionTable* nxt = cur->collision_list_next();
 532       // If the entire region is dead, eliminate.
 533       log_develop_trace(gc, remset, scrub)("     For other region %u:", cur->hr()->hrm_index());
 534       if (!live_data->is_region_live(cur->hr()->hrm_index())) {
 535         *prev = nxt;
 536         cur->set_collision_list_next(NULL);
 537         _n_fine_entries--;
 538         log_develop_trace(gc, remset, scrub)("          deleted via region map.");
 539         unlink_from_all(cur);
 540         PerRegionTable::free(cur);
 541       } else {
 542         // Do fine-grain elimination.
 543         log_develop_trace(gc, remset, scrub)("          occ: before = %4d.", cur->occupied());
 544         cur->scrub(live_data);
 545         log_develop_trace(gc, remset, scrub)("          after = %4d.", cur->occupied());
 546         // Did that empty the table completely?
 547         if (cur->occupied() == 0) {
 548           *prev = nxt;
 549           cur->set_collision_list_next(NULL);
 550           _n_fine_entries--;
 551           unlink_from_all(cur);
 552           PerRegionTable::free(cur);
 553         } else {
 554           prev = cur->collision_list_next_addr();
 555         }
 556       }
 557       cur = nxt;
 558     }
 559   }
 560   // Since we may have deleted a from_card_cache entry from the RS, clear
 561   // the FCC.
 562   clear_fcc();
 563 }
 564 
 565 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
 566   if (limit <= (size_t)G1RSetSparseRegionEntries) {
 567     return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
 568   } else {
 569     // Current uses of this method may only use values less than G1RSetSparseRegionEntries
 570     // for the limit. The solution, comparing against occupied() would be too slow
 571     // at this time.
 572     Unimplemented();
 573     return false;
 574   }
 575 }
 576 
 577 bool OtherRegionsTable::is_empty() const {
 578   return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
 579 }
 580 
 581 size_t OtherRegionsTable::occupied() const {
 582   size_t sum = occ_fine();
 583   sum += occ_sparse();
 584   sum += occ_coarse();
 585   return sum;
 586 }
 587 
 588 size_t OtherRegionsTable::occ_fine() const {
 589   size_t sum = 0;
 590 
 591   size_t num = 0;
 592   PerRegionTable * cur = _first_all_fine_prts;
 593   while (cur != NULL) {
 594     sum += cur->occupied();
 595     cur = cur->next();
 596     num++;
 597   }
 598   guarantee(num == _n_fine_entries, "just checking");
 599   return sum;
 600 }
 601 
 602 size_t OtherRegionsTable::occ_coarse() const {
 603   return (_n_coarse_entries * HeapRegion::CardsPerRegion);
 604 }
 605 
 606 size_t OtherRegionsTable::occ_sparse() const {
 607   return _sparse_table.occupied();
 608 }
 609 
 610 size_t OtherRegionsTable::mem_size() const {
 611   size_t sum = 0;
 612   // all PRTs are of the same size so it is sufficient to query only one of them.
 613   if (_first_all_fine_prts != NULL) {
 614     assert(_last_all_fine_prts != NULL &&
 615       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
 616     sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
 617   }
 618   sum += (sizeof(PerRegionTable*) * _max_fine_entries);
 619   sum += (_coarse_map.size_in_words() * HeapWordSize);
 620   sum += (_sparse_table.mem_size());
 621   sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
 622   return sum;
 623 }
 624 
 625 size_t OtherRegionsTable::static_mem_size() {
 626   return G1FromCardCache::static_mem_size();
 627 }
 628 
 629 size_t OtherRegionsTable::fl_mem_size() {
 630   return PerRegionTable::fl_mem_size();
 631 }
 632 
 633 void OtherRegionsTable::clear_fcc() {
 634   G1FromCardCache::clear(_hr->hrm_index());
 635 }
 636 
 637 void OtherRegionsTable::clear() {
 638   // if there are no entries, skip this step
 639   if (_first_all_fine_prts != NULL) {
 640     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
 641     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
 642     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
 643   } else {
 644     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
 645   }
 646 
 647   _first_all_fine_prts = _last_all_fine_prts = NULL;
 648   _sparse_table.clear();
 649   _coarse_map.clear();
 650   _n_fine_entries = 0;
 651   _n_coarse_entries = 0;
 652 
 653   clear_fcc();
 654 }
 655 
 656 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 657   // Cast away const in this case.
 658   MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
 659   return contains_reference_locked(from);
 660 }
 661 
 662 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
 663   HeapRegion* hr = _g1h->heap_region_containing(from);
 664   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
 665   // Is this region in the coarse map?
 666   if (_coarse_map.at(hr_ind)) return true;
 667 
 668   PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
 669                                      hr);
 670   if (prt != NULL) {
 671     return prt->contains_reference(from);
 672 
 673   } else {
 674     uintptr_t from_card =
 675       (uintptr_t(from) >> CardTableModRefBS::card_shift);
 676     uintptr_t hr_bot_card_index =
 677       uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
 678     assert(from_card >= hr_bot_card_index, "Inv");
 679     CardIdx_t card_index = from_card - hr_bot_card_index;
 680     assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 681            "Must be in range.");
 682     return _sparse_table.contains_card(hr_ind, card_index);
 683   }
 684 }
 685 
 686 void
 687 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 688   _sparse_table.do_cleanup_work(hrrs_cleanup_task);
 689 }
 690 
 691 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
 692                                    HeapRegion* hr)
 693   : _bot(bot),
 694     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
 695     _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
 696   reset_for_par_iteration();
 697 }
 698 
 699 void HeapRegionRemSet::setup_remset_size() {
 700   // Setup sparse and fine-grain tables sizes.
 701   // table_size = base * (log(region_size / 1M) + 1)
 702   const int LOG_M = 20;
 703   int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
 704   if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
 705     G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
 706   }
 707   if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
 708     G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
 709   }
 710   guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
 711 }
 712 
 713 bool HeapRegionRemSet::claim_iter() {
 714   if (_iter_state != Unclaimed) return false;
 715   jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
 716   return (res == Unclaimed);
 717 }
 718 
 719 void HeapRegionRemSet::set_iter_complete() {
 720   _iter_state = Complete;
 721 }
 722 
 723 bool HeapRegionRemSet::iter_is_complete() {
 724   return _iter_state == Complete;
 725 }
 726 
 727 #ifndef PRODUCT
 728 void HeapRegionRemSet::print() {
 729   HeapRegionRemSetIterator iter(this);
 730   size_t card_index;
 731   while (iter.has_next(card_index)) {
 732     HeapWord* card_start = _bot->address_for_index(card_index);
 733     tty->print_cr("  Card " PTR_FORMAT, p2i(card_start));
 734   }
 735   if (iter.n_yielded() != occupied()) {
 736     tty->print_cr("Yielded disagrees with occupied:");
 737     tty->print_cr("  " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
 738                   " coarse, " SIZE_FORMAT_W(6) " fine).",
 739                   iter.n_yielded(),
 740                   iter.n_yielded_coarse(), iter.n_yielded_fine());
 741     tty->print_cr("  " SIZE_FORMAT_W(6) " occ     (" SIZE_FORMAT_W(6)
 742                            " coarse, " SIZE_FORMAT_W(6) " fine).",
 743                   occupied(), occ_coarse(), occ_fine());
 744   }
 745   guarantee(iter.n_yielded() == occupied(),
 746             "We should have yielded all the represented cards.");
 747 }
 748 #endif
 749 
 750 void HeapRegionRemSet::cleanup() {
 751   SparsePRT::cleanup_all();
 752 }
 753 
 754 void HeapRegionRemSet::clear() {
 755   MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 756   clear_locked();
 757 }
 758 
 759 void HeapRegionRemSet::clear_locked() {
 760   _code_roots.clear();
 761   _other_regions.clear();
 762   assert(occupied_locked() == 0, "Should be clear.");
 763   reset_for_par_iteration();
 764 }
 765 
 766 void HeapRegionRemSet::reset_for_par_iteration() {
 767   _iter_state = Unclaimed;
 768   _iter_claimed = 0;
 769   // It's good to check this to make sure that the two methods are in sync.
 770   assert(verify_ready_for_par_iteration(), "post-condition");
 771 }
 772 
 773 void HeapRegionRemSet::scrub(G1CardLiveData* live_data) {
 774   _other_regions.scrub(live_data);
 775 }
 776 
 777 // Code roots support
 778 //
 779 // The code root set is protected by two separate locking schemes
 780 // When at safepoint the per-hrrs lock must be held during modifications
 781 // except when doing a full gc.
 782 // When not at safepoint the CodeCache_lock must be held during modifications.
 783 // When concurrent readers access the contains() function
 784 // (during the evacuation phase) no removals are allowed.
 785 
 786 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
 787   assert(nm != NULL, "sanity");
 788   assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
 789           "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
 790           BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
 791   // Optimistic unlocked contains-check
 792   if (!_code_roots.contains(nm)) {
 793     MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
 794     add_strong_code_root_locked(nm);
 795   }
 796 }
 797 
 798 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
 799   assert(nm != NULL, "sanity");
 800   assert((CodeCache_lock->owned_by_self() ||
 801          (SafepointSynchronize::is_at_safepoint() &&
 802           (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
 803           "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
 804           BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
 805           BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
 806   _code_roots.add(nm);
 807 }
 808 
 809 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
 810   assert(nm != NULL, "sanity");
 811   assert_locked_or_safepoint(CodeCache_lock);
 812 
 813   MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
 814   _code_roots.remove(nm);
 815 
 816   // Check that there were no duplicates
 817   guarantee(!_code_roots.contains(nm), "duplicate entry found");
 818 }
 819 
 820 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
 821   _code_roots.nmethods_do(blk);
 822 }
 823 
 824 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
 825   _code_roots.clean(hr);
 826 }
 827 
 828 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
 829   return _code_roots.mem_size();
 830 }
 831 
 832 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
 833   _hrrs(hrrs),
 834   _g1h(G1CollectedHeap::heap()),
 835   _coarse_map(&hrrs->_other_regions._coarse_map),
 836   _bot(hrrs->_bot),
 837   _is(Sparse),
 838   // Set these values so that we increment to the first region.
 839   _coarse_cur_region_index(-1),
 840   _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
 841   _cur_card_in_prt(HeapRegion::CardsPerRegion),
 842   _fine_cur_prt(NULL),
 843   _n_yielded_coarse(0),
 844   _n_yielded_fine(0),
 845   _n_yielded_sparse(0),
 846   _sparse_iter(&hrrs->_other_regions._sparse_table) {}
 847 
 848 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
 849   if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
 850   // Go to the next card.
 851   _coarse_cur_region_cur_card++;
 852   // Was the last the last card in the current region?
 853   if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
 854     // Yes: find the next region.  This may leave _coarse_cur_region_index
 855     // Set to the last index, in which case there are no more coarse
 856     // regions.
 857     _coarse_cur_region_index =
 858       (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
 859     if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
 860       _coarse_cur_region_cur_card = 0;
 861       HeapWord* r_bot =
 862         _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
 863       _cur_region_card_offset = _bot->index_for(r_bot);
 864     } else {
 865       return false;
 866     }
 867   }
 868   // If we didn't return false above, then we can yield a card.
 869   card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
 870   return true;
 871 }
 872 
 873 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
 874   if (fine_has_next()) {
 875     _cur_card_in_prt =
 876       _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 877   }
 878   if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
 879     // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
 880     // the remembered set.
 881     if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
 882       return false;
 883     }
 884     PerRegionTable* next_prt = _fine_cur_prt->next();
 885     switch_to_prt(next_prt);
 886     _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 887   }
 888 
 889   card_index = _cur_region_card_offset + _cur_card_in_prt;
 890   guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
 891             "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
 892   return true;
 893 }
 894 
 895 bool HeapRegionRemSetIterator::fine_has_next() {
 896   return _cur_card_in_prt != HeapRegion::CardsPerRegion;
 897 }
 898 
 899 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
 900   assert(prt != NULL, "Cannot switch to NULL prt");
 901   _fine_cur_prt = prt;
 902 
 903   HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
 904   _cur_region_card_offset = _bot->index_for(r_bot);
 905 
 906   // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
 907   // To avoid special-casing this start case, and not miss the first bitmap
 908   // entry, initialize _cur_region_cur_card with -1 instead of 0.
 909   _cur_card_in_prt = (size_t)-1;
 910 }
 911 
 912 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
 913   switch (_is) {
 914   case Sparse: {
 915     if (_sparse_iter.has_next(card_index)) {
 916       _n_yielded_sparse++;
 917       return true;
 918     }
 919     // Otherwise, deliberate fall-through
 920     _is = Fine;
 921     PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
 922     if (initial_fine_prt != NULL) {
 923       switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
 924     }
 925   }
 926   case Fine:
 927     if (fine_has_next(card_index)) {
 928       _n_yielded_fine++;
 929       return true;
 930     }
 931     // Otherwise, deliberate fall-through
 932     _is = Coarse;
 933   case Coarse:
 934     if (coarse_has_next(card_index)) {
 935       _n_yielded_coarse++;
 936       return true;
 937     }
 938     // Otherwise...
 939     break;
 940   }
 941   assert(ParallelGCThreads > 1 ||
 942          n_yielded() == _hrrs->occupied(),
 943          "Should have yielded all the cards in the rem set "
 944          "(in the non-par case).");
 945   return false;
 946 }
 947 
 948 void HeapRegionRemSet::reset_for_cleanup_tasks() {
 949   SparsePRT::reset_for_cleanup_tasks();
 950 }
 951 
 952 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 953   _other_regions.do_cleanup_work(hrrs_cleanup_task);
 954 }
 955 
 956 void
 957 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
 958   SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
 959 }
 960 
 961 #ifndef PRODUCT
 962 void HeapRegionRemSet::test() {
 963   os::sleep(Thread::current(), (jlong)5000, false);
 964   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 965 
 966   // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
 967   // hash bucket.
 968   HeapRegion* hr0 = g1h->region_at(0);
 969   HeapRegion* hr1 = g1h->region_at(1);
 970   HeapRegion* hr2 = g1h->region_at(5);
 971   HeapRegion* hr3 = g1h->region_at(6);
 972   HeapRegion* hr4 = g1h->region_at(7);
 973   HeapRegion* hr5 = g1h->region_at(8);
 974 
 975   HeapWord* hr1_start = hr1->bottom();
 976   HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
 977   HeapWord* hr1_last = hr1->end() - 1;
 978 
 979   HeapWord* hr2_start = hr2->bottom();
 980   HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
 981   HeapWord* hr2_last = hr2->end() - 1;
 982 
 983   HeapWord* hr3_start = hr3->bottom();
 984   HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
 985   HeapWord* hr3_last = hr3->end() - 1;
 986 
 987   HeapRegionRemSet* hrrs = hr0->rem_set();
 988 
 989   // Make three references from region 0x101...
 990   hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
 991   hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
 992   hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
 993 
 994   hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
 995   hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
 996   hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
 997 
 998   hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
 999   hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1000   hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1001 
1002   // Now cause a coarsening.
1003   hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1004   hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1005 
1006   // Now, does iteration yield these three?
1007   HeapRegionRemSetIterator iter(hrrs);
1008   size_t sum = 0;
1009   size_t card_index;
1010   while (iter.has_next(card_index)) {
1011     HeapWord* card_start =
1012       G1CollectedHeap::heap()->bot()->address_for_index(card_index);
1013     tty->print_cr("  Card " PTR_FORMAT ".", p2i(card_start));
1014     sum++;
1015   }
1016   guarantee(sum == 11 - 3 + 2048, "Failure");
1017   guarantee(sum == hrrs->occupied(), "Failure");
1018 }
1019 #endif