1 /*
   2  * Copyright (c) 2001, 2017, 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/g1BlockOffsetTable.inline.hpp"
  27 #include "gc/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc/g1/g1ConcurrentRefine.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.hpp"
  37 #include "utilities/bitMap.inline.hpp"
  38 #include "utilities/debug.hpp"
  39 #include "utilities/formatBuffer.hpp"
  40 #include "utilities/globalDefinitions.hpp"
  41 #include "utilities/growableArray.hpp"
  42 
  43 class PerRegionTable: public CHeapObj<mtGC> {
  44   friend class OtherRegionsTable;
  45   friend class HeapRegionRemSetIterator;
  46 
  47   HeapRegion*     _hr;
  48   CHeapBitMap     _bm;
  49   jint            _occupied;
  50 
  51   // next pointer for free/allocated 'all' list
  52   PerRegionTable* _next;
  53 
  54   // prev pointer for the allocated 'all' list
  55   PerRegionTable* _prev;
  56 
  57   // next pointer in collision list
  58   PerRegionTable * _collision_list_next;
  59 
  60   // Global free list of PRTs
  61   static PerRegionTable* volatile _free_list;
  62 
  63 protected:
  64   // We need access in order to union things into the base table.
  65   BitMap* bm() { return &_bm; }
  66 
  67   void recount_occupied() {
  68     _occupied = (jint) bm()->count_one_bits();
  69   }
  70 
  71   PerRegionTable(HeapRegion* hr) :
  72     _hr(hr),
  73     _occupied(0),
  74     _bm(HeapRegion::CardsPerRegion, mtGC),
  75     _collision_list_next(NULL), _next(NULL), _prev(NULL)
  76   {}
  77 
  78   void add_card_work(CardIdx_t from_card, bool par) {
  79     if (!_bm.at(from_card)) {
  80       if (par) {
  81         if (_bm.par_at_put(from_card, 1)) {
  82           Atomic::inc(&_occupied);
  83         }
  84       } else {
  85         _bm.at_put(from_card, 1);
  86         _occupied++;
  87       }
  88     }
  89   }
  90 
  91   void add_reference_work(OopOrNarrowOopStar from, bool par) {
  92     // Must make this robust in case "from" is not in "_hr", because of
  93     // concurrency.
  94 
  95     HeapRegion* loc_hr = hr();
  96     // If the test below fails, then this table was reused concurrently
  97     // with this operation.  This is OK, since the old table was coarsened,
  98     // and adding a bit to the new table is never incorrect.
  99     // If the table used to belong to a continues humongous region and is
 100     // now reused for the corresponding start humongous region, we need to
 101     // make sure that we detect this. Thus, we call is_in_reserved_raw()
 102     // instead of just is_in_reserved() here.
 103     if (loc_hr->is_in_reserved(from)) {
 104       size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
 105       CardIdx_t from_card = (CardIdx_t)
 106           hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
 107 
 108       assert((size_t)from_card < HeapRegion::CardsPerRegion,
 109              "Must be in range.");
 110       add_card_work(from_card, par);
 111     }
 112   }
 113 
 114 public:
 115 
 116   HeapRegion* hr() const { return OrderAccess::load_acquire(&_hr); }
 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(&_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 = Atomic::cmpxchg(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 = Atomic::cmpxchg(nxt, &_free_list, fl);
 201       if (res == fl) {
 202         fl->init(hr, true);
 203         return fl;
 204       } else {
 205         fl = _free_list;
 206       }
 207     }
 208     assert(fl == NULL, "Loop condition.");
 209     return new PerRegionTable(hr);
 210   }
 211 
 212   PerRegionTable* next() const { return _next; }
 213   void set_next(PerRegionTable* next) { _next = next; }
 214   PerRegionTable* prev() const { return _prev; }
 215   void set_prev(PerRegionTable* prev) { _prev = prev; }
 216 
 217   // Accessor and Modification routines for the pointer for the
 218   // singly linked collision list that links the PRTs within the
 219   // OtherRegionsTable::_fine_grain_regions hash table.
 220   //
 221   // It might be useful to also make the collision list doubly linked
 222   // to avoid iteration over the collisions list during scrubbing/deletion.
 223   // OTOH there might not be many collisions.
 224 
 225   PerRegionTable* collision_list_next() const {
 226     return _collision_list_next;
 227   }
 228 
 229   void set_collision_list_next(PerRegionTable* next) {
 230     _collision_list_next = next;
 231   }
 232 
 233   PerRegionTable** collision_list_next_addr() {
 234     return &_collision_list_next;
 235   }
 236 
 237   static size_t fl_mem_size() {
 238     PerRegionTable* cur = _free_list;
 239     size_t res = 0;
 240     while (cur != NULL) {
 241       res += cur->mem_size();
 242       cur = cur->next();
 243     }
 244     return res;
 245   }
 246 
 247   static void test_fl_mem_size();
 248 };
 249 
 250 PerRegionTable* volatile PerRegionTable::_free_list = NULL;
 251 
 252 size_t OtherRegionsTable::_max_fine_entries = 0;
 253 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
 254 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 255 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 256 
 257 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
 258   _g1h(G1CollectedHeap::heap()),
 259   _hr(hr), _m(m),
 260   _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
 261   _fine_grain_regions(NULL),
 262   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
 263   _n_fine_entries(0), _n_coarse_entries(0),
 264   _fine_eviction_start(0),
 265   _sparse_table(hr)
 266 {
 267   typedef PerRegionTable* PerRegionTablePtr;
 268 
 269   if (_max_fine_entries == 0) {
 270     assert(_mod_max_fine_entries_mask == 0, "Both or none.");
 271     size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
 272     _max_fine_entries = (size_t)1 << max_entries_log;
 273     _mod_max_fine_entries_mask = _max_fine_entries - 1;
 274 
 275     assert(_fine_eviction_sample_size == 0
 276            && _fine_eviction_stride == 0, "All init at same time.");
 277     _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
 278     _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
 279   }
 280 
 281   _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
 282                         mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 283 
 284   if (_fine_grain_regions == NULL) {
 285     vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
 286                           "Failed to allocate _fine_grain_entries.");
 287   }
 288 
 289   for (size_t i = 0; i < _max_fine_entries; i++) {
 290     _fine_grain_regions[i] = NULL;
 291   }
 292 }
 293 
 294 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
 295   // We always append to the beginning of the list for convenience;
 296   // the order of entries in this list does not matter.
 297   if (_first_all_fine_prts != NULL) {
 298     assert(_first_all_fine_prts->prev() == NULL, "invariant");
 299     _first_all_fine_prts->set_prev(prt);
 300     prt->set_next(_first_all_fine_prts);
 301   } else {
 302     // this is the first element we insert. Adjust the "last" pointer
 303     _last_all_fine_prts = prt;
 304     assert(prt->next() == NULL, "just checking");
 305   }
 306   // the new element is always the first element without a predecessor
 307   prt->set_prev(NULL);
 308   _first_all_fine_prts = prt;
 309 
 310   assert(prt->prev() == NULL, "just checking");
 311   assert(_first_all_fine_prts == prt, "just checking");
 312   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 313          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 314          "just checking");
 315   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 316          "just checking");
 317   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 318          "just checking");
 319 }
 320 
 321 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
 322   if (prt->prev() != NULL) {
 323     assert(_first_all_fine_prts != prt, "just checking");
 324     prt->prev()->set_next(prt->next());
 325     // removing the last element in the list?
 326     if (_last_all_fine_prts == prt) {
 327       _last_all_fine_prts = prt->prev();
 328     }
 329   } else {
 330     assert(_first_all_fine_prts == prt, "just checking");
 331     _first_all_fine_prts = prt->next();
 332     // list is empty now?
 333     if (_first_all_fine_prts == NULL) {
 334       _last_all_fine_prts = NULL;
 335     }
 336   }
 337 
 338   if (prt->next() != NULL) {
 339     prt->next()->set_prev(prt->prev());
 340   }
 341 
 342   prt->set_next(NULL);
 343   prt->set_prev(NULL);
 344 
 345   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 346          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 347          "just checking");
 348   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 349          "just checking");
 350   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 351          "just checking");
 352 }
 353 
 354 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
 355   uint cur_hrm_ind = _hr->hrm_index();
 356 
 357   int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
 358 
 359   if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
 360     assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
 361     return;
 362   }
 363 
 364   // Note that this may be a continued H region.
 365   HeapRegion* from_hr = _g1h->heap_region_containing(from);
 366   RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
 367 
 368   // If the region is already coarsened, return.
 369   if (_coarse_map.at(from_hrm_ind)) {
 370     assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
 371     return;
 372   }
 373 
 374   // Otherwise find a per-region table to add it to.
 375   size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
 376   PerRegionTable* prt = find_region_table(ind, from_hr);
 377   if (prt == NULL) {
 378     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
 379     // Confirm that it's really not there...
 380     prt = find_region_table(ind, from_hr);
 381     if (prt == NULL) {
 382 
 383       uintptr_t from_hr_bot_card_index =
 384         uintptr_t(from_hr->bottom())
 385           >> CardTableModRefBS::card_shift;
 386       CardIdx_t card_index = from_card - from_hr_bot_card_index;
 387       assert((size_t)card_index < HeapRegion::CardsPerRegion,
 388              "Must be in range.");
 389       if (G1HRRSUseSparseTable &&
 390           _sparse_table.add_card(from_hrm_ind, card_index)) {
 391         assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
 392         return;
 393       }
 394 
 395       if (_n_fine_entries == _max_fine_entries) {
 396         prt = delete_region_table();
 397         // There is no need to clear the links to the 'all' list here:
 398         // prt will be reused immediately, i.e. remain in the 'all' list.
 399         prt->init(from_hr, false /* clear_links_to_all_list */);
 400       } else {
 401         prt = PerRegionTable::alloc(from_hr);
 402         link_to_all(prt);
 403       }
 404 
 405       PerRegionTable* first_prt = _fine_grain_regions[ind];
 406       prt->set_collision_list_next(first_prt);
 407       // The assignment into _fine_grain_regions allows the prt to
 408       // start being used concurrently. In addition to
 409       // collision_list_next which must be visible (else concurrent
 410       // parsing of the list, if any, may fail to see other entries),
 411       // the content of the prt must be visible (else for instance
 412       // some mark bits may not yet seem cleared or a 'later' update
 413       // performed by a concurrent thread could be undone when the
 414       // zeroing becomes visible). This requires store ordering.
 415       OrderAccess::release_store(&_fine_grain_regions[ind], prt);
 416       _n_fine_entries++;
 417 
 418       if (G1HRRSUseSparseTable) {
 419         // Transfer from sparse to fine-grain.
 420         SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
 421         assert(sprt_entry != NULL, "There should have been an entry");
 422         for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
 423           CardIdx_t c = sprt_entry->card(i);
 424           prt->add_card(c);
 425         }
 426         // Now we can delete the sparse entry.
 427         bool res = _sparse_table.delete_entry(from_hrm_ind);
 428         assert(res, "It should have been there.");
 429       }
 430     }
 431     assert(prt != NULL && prt->hr() == from_hr, "consequence");
 432   }
 433   // Note that we can't assert "prt->hr() == from_hr", because of the
 434   // possibility of concurrent reuse.  But see head comment of
 435   // OtherRegionsTable for why this is OK.
 436   assert(prt != NULL, "Inv");
 437 
 438   prt->add_reference(from);
 439   assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT", p2i(from));
 440 }
 441 
 442 PerRegionTable*
 443 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
 444   assert(ind < _max_fine_entries, "Preconditions.");
 445   PerRegionTable* prt = _fine_grain_regions[ind];
 446   while (prt != NULL && prt->hr() != hr) {
 447     prt = prt->collision_list_next();
 448   }
 449   // Loop postcondition is the method postcondition.
 450   return prt;
 451 }
 452 
 453 jint OtherRegionsTable::_n_coarsenings = 0;
 454 
 455 PerRegionTable* OtherRegionsTable::delete_region_table() {
 456   assert(_m->owned_by_self(), "Precondition");
 457   assert(_n_fine_entries == _max_fine_entries, "Precondition");
 458   PerRegionTable* max = NULL;
 459   jint max_occ = 0;
 460   PerRegionTable** max_prev = NULL;
 461   size_t max_ind;
 462 
 463   size_t i = _fine_eviction_start;
 464   for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
 465     size_t ii = i;
 466     // Make sure we get a non-NULL sample.
 467     while (_fine_grain_regions[ii] == NULL) {
 468       ii++;
 469       if (ii == _max_fine_entries) ii = 0;
 470       guarantee(ii != i, "We must find one.");
 471     }
 472     PerRegionTable** prev = &_fine_grain_regions[ii];
 473     PerRegionTable* cur = *prev;
 474     while (cur != NULL) {
 475       jint cur_occ = cur->occupied();
 476       if (max == NULL || cur_occ > max_occ) {
 477         max = cur;
 478         max_prev = prev;
 479         max_ind = i;
 480         max_occ = cur_occ;
 481       }
 482       prev = cur->collision_list_next_addr();
 483       cur = cur->collision_list_next();
 484     }
 485     i = i + _fine_eviction_stride;
 486     if (i >= _n_fine_entries) i = i - _n_fine_entries;
 487   }
 488 
 489   _fine_eviction_start++;
 490 
 491   if (_fine_eviction_start >= _n_fine_entries) {
 492     _fine_eviction_start -= _n_fine_entries;
 493   }
 494 
 495   guarantee(max != NULL, "Since _n_fine_entries > 0");
 496   guarantee(max_prev != NULL, "Since max != NULL.");
 497 
 498   // Set the corresponding coarse bit.
 499   size_t max_hrm_index = (size_t) max->hr()->hrm_index();
 500   if (!_coarse_map.at(max_hrm_index)) {
 501     _coarse_map.at_put(max_hrm_index, true);
 502     _n_coarse_entries++;
 503   }
 504 
 505   // Unsplice.
 506   *max_prev = max->collision_list_next();
 507   Atomic::inc(&_n_coarsenings);
 508   _n_fine_entries--;
 509   return max;
 510 }
 511 
 512 void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
 513   // First eliminated garbage regions from the coarse map.
 514   log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
 515 
 516   log_develop_trace(gc, remset, scrub)("   Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
 517   if (_n_coarse_entries > 0) {
 518     live_data->remove_nonlive_regions(&_coarse_map);
 519     _n_coarse_entries = _coarse_map.count_one_bits();
 520   }
 521   log_develop_trace(gc, remset, scrub)("   after = " SIZE_FORMAT ".", _n_coarse_entries);
 522 
 523   // Now do the fine-grained maps.
 524   for (size_t i = 0; i < _max_fine_entries; i++) {
 525     PerRegionTable* cur = _fine_grain_regions[i];
 526     PerRegionTable** prev = &_fine_grain_regions[i];
 527     while (cur != NULL) {
 528       PerRegionTable* nxt = cur->collision_list_next();
 529       // If the entire region is dead, eliminate.
 530       log_develop_trace(gc, remset, scrub)("     For other region %u:", cur->hr()->hrm_index());
 531       if (!live_data->is_region_live(cur->hr()->hrm_index())) {
 532         *prev = nxt;
 533         cur->set_collision_list_next(NULL);
 534         _n_fine_entries--;
 535         log_develop_trace(gc, remset, scrub)("          deleted via region map.");
 536         unlink_from_all(cur);
 537         PerRegionTable::free(cur);
 538       } else {
 539         // Do fine-grain elimination.
 540         log_develop_trace(gc, remset, scrub)("          occ: before = %4d.", cur->occupied());
 541         cur->scrub(live_data);
 542         log_develop_trace(gc, remset, scrub)("          after = %4d.", cur->occupied());
 543         // Did that empty the table completely?
 544         if (cur->occupied() == 0) {
 545           *prev = nxt;
 546           cur->set_collision_list_next(NULL);
 547           _n_fine_entries--;
 548           unlink_from_all(cur);
 549           PerRegionTable::free(cur);
 550         } else {
 551           prev = cur->collision_list_next_addr();
 552         }
 553       }
 554       cur = nxt;
 555     }
 556   }
 557   // Since we may have deleted a from_card_cache entry from the RS, clear
 558   // the FCC.
 559   clear_fcc();
 560 }
 561 
 562 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
 563   if (limit <= (size_t)G1RSetSparseRegionEntries) {
 564     return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
 565   } else {
 566     // Current uses of this method may only use values less than G1RSetSparseRegionEntries
 567     // for the limit. The solution, comparing against occupied() would be too slow
 568     // at this time.
 569     Unimplemented();
 570     return false;
 571   }
 572 }
 573 
 574 bool OtherRegionsTable::is_empty() const {
 575   return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
 576 }
 577 
 578 size_t OtherRegionsTable::occupied() const {
 579   size_t sum = occ_fine();
 580   sum += occ_sparse();
 581   sum += occ_coarse();
 582   return sum;
 583 }
 584 
 585 size_t OtherRegionsTable::occ_fine() const {
 586   size_t sum = 0;
 587 
 588   size_t num = 0;
 589   PerRegionTable * cur = _first_all_fine_prts;
 590   while (cur != NULL) {
 591     sum += cur->occupied();
 592     cur = cur->next();
 593     num++;
 594   }
 595   guarantee(num == _n_fine_entries, "just checking");
 596   return sum;
 597 }
 598 
 599 size_t OtherRegionsTable::occ_coarse() const {
 600   return (_n_coarse_entries * HeapRegion::CardsPerRegion);
 601 }
 602 
 603 size_t OtherRegionsTable::occ_sparse() const {
 604   return _sparse_table.occupied();
 605 }
 606 
 607 size_t OtherRegionsTable::mem_size() const {
 608   size_t sum = 0;
 609   // all PRTs are of the same size so it is sufficient to query only one of them.
 610   if (_first_all_fine_prts != NULL) {
 611     assert(_last_all_fine_prts != NULL &&
 612       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
 613     sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
 614   }
 615   sum += (sizeof(PerRegionTable*) * _max_fine_entries);
 616   sum += (_coarse_map.size_in_words() * HeapWordSize);
 617   sum += (_sparse_table.mem_size());
 618   sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
 619   return sum;
 620 }
 621 
 622 size_t OtherRegionsTable::static_mem_size() {
 623   return G1FromCardCache::static_mem_size();
 624 }
 625 
 626 size_t OtherRegionsTable::fl_mem_size() {
 627   return PerRegionTable::fl_mem_size();
 628 }
 629 
 630 void OtherRegionsTable::clear_fcc() {
 631   G1FromCardCache::clear(_hr->hrm_index());
 632 }
 633 
 634 void OtherRegionsTable::clear() {
 635   // if there are no entries, skip this step
 636   if (_first_all_fine_prts != NULL) {
 637     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
 638     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
 639     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
 640   } else {
 641     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
 642   }
 643 
 644   _first_all_fine_prts = _last_all_fine_prts = NULL;
 645   _sparse_table.clear();
 646   if (_n_coarse_entries > 0) {
 647     _coarse_map.clear();
 648   }
 649   _n_fine_entries = 0;
 650   _n_coarse_entries = 0;
 651 
 652   clear_fcc();
 653 }
 654 
 655 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 656   // Cast away const in this case.
 657   MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
 658   return contains_reference_locked(from);
 659 }
 660 
 661 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
 662   HeapRegion* hr = _g1h->heap_region_containing(from);
 663   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
 664   // Is this region in the coarse map?
 665   if (_coarse_map.at(hr_ind)) return true;
 666 
 667   PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
 668                                      hr);
 669   if (prt != NULL) {
 670     return prt->contains_reference(from);
 671 
 672   } else {
 673     uintptr_t from_card =
 674       (uintptr_t(from) >> CardTableModRefBS::card_shift);
 675     uintptr_t hr_bot_card_index =
 676       uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
 677     assert(from_card >= hr_bot_card_index, "Inv");
 678     CardIdx_t card_index = from_card - hr_bot_card_index;
 679     assert((size_t)card_index < HeapRegion::CardsPerRegion,
 680            "Must be in range.");
 681     return _sparse_table.contains_card(hr_ind, card_index);
 682   }
 683 }
 684 
 685 void
 686 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 687   _sparse_table.do_cleanup_work(hrrs_cleanup_task);
 688 }
 689 
 690 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
 691                                    HeapRegion* hr)
 692   : _bot(bot),
 693     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
 694     _code_roots(),
 695     _other_regions(hr, &_m) {
 696 }
 697 
 698 void HeapRegionRemSet::setup_remset_size() {
 699   // Setup sparse and fine-grain tables sizes.
 700   // table_size = base * (log(region_size / 1M) + 1)
 701   const int LOG_M = 20;
 702   int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
 703   if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
 704     G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
 705   }
 706   if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
 707     G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
 708   }
 709   guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
 710 }
 711 
 712 void HeapRegionRemSet::cleanup() {
 713   SparsePRT::cleanup_all();
 714 }
 715 
 716 void HeapRegionRemSet::clear() {
 717   MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 718   clear_locked();
 719 }
 720 
 721 void HeapRegionRemSet::clear_locked() {
 722   _code_roots.clear();
 723   _other_regions.clear();
 724   assert(occupied_locked() == 0, "Should be clear.");
 725 }
 726 
 727 void HeapRegionRemSet::scrub(G1CardLiveData* live_data) {
 728   _other_regions.scrub(live_data);
 729 }
 730 
 731 // Code roots support
 732 //
 733 // The code root set is protected by two separate locking schemes
 734 // When at safepoint the per-hrrs lock must be held during modifications
 735 // except when doing a full gc.
 736 // When not at safepoint the CodeCache_lock must be held during modifications.
 737 // When concurrent readers access the contains() function
 738 // (during the evacuation phase) no removals are allowed.
 739 
 740 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
 741   assert(nm != NULL, "sanity");
 742   assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
 743           "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
 744           BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
 745   // Optimistic unlocked contains-check
 746   if (!_code_roots.contains(nm)) {
 747     MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
 748     add_strong_code_root_locked(nm);
 749   }
 750 }
 751 
 752 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
 753   assert(nm != NULL, "sanity");
 754   assert((CodeCache_lock->owned_by_self() ||
 755          (SafepointSynchronize::is_at_safepoint() &&
 756           (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
 757           "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
 758           BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
 759           BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
 760   _code_roots.add(nm);
 761 }
 762 
 763 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
 764   assert(nm != NULL, "sanity");
 765   assert_locked_or_safepoint(CodeCache_lock);
 766 
 767   MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
 768   _code_roots.remove(nm);
 769 
 770   // Check that there were no duplicates
 771   guarantee(!_code_roots.contains(nm), "duplicate entry found");
 772 }
 773 
 774 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
 775   _code_roots.nmethods_do(blk);
 776 }
 777 
 778 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
 779   _code_roots.clean(hr);
 780 }
 781 
 782 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
 783   return _code_roots.mem_size();
 784 }
 785 
 786 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
 787   _hrrs(hrrs),
 788   _g1h(G1CollectedHeap::heap()),
 789   _coarse_map(&hrrs->_other_regions._coarse_map),
 790   _bot(hrrs->_bot),
 791   _is(Sparse),
 792   // Set these values so that we increment to the first region.
 793   _coarse_cur_region_index(-1),
 794   _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
 795   _cur_card_in_prt(HeapRegion::CardsPerRegion),
 796   _fine_cur_prt(NULL),
 797   _n_yielded_coarse(0),
 798   _n_yielded_fine(0),
 799   _n_yielded_sparse(0),
 800   _sparse_iter(&hrrs->_other_regions._sparse_table) {}
 801 
 802 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
 803   if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
 804   // Go to the next card.
 805   _coarse_cur_region_cur_card++;
 806   // Was the last the last card in the current region?
 807   if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
 808     // Yes: find the next region.  This may leave _coarse_cur_region_index
 809     // Set to the last index, in which case there are no more coarse
 810     // regions.
 811     _coarse_cur_region_index =
 812       (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
 813     if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
 814       _coarse_cur_region_cur_card = 0;
 815       HeapWord* r_bot =
 816         _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
 817       _cur_region_card_offset = _bot->index_for(r_bot);
 818     } else {
 819       return false;
 820     }
 821   }
 822   // If we didn't return false above, then we can yield a card.
 823   card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
 824   return true;
 825 }
 826 
 827 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
 828   if (fine_has_next()) {
 829     _cur_card_in_prt =
 830       _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 831   }
 832   if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
 833     // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
 834     // the remembered set.
 835     if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
 836       return false;
 837     }
 838     PerRegionTable* next_prt = _fine_cur_prt->next();
 839     switch_to_prt(next_prt);
 840     _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 841   }
 842 
 843   card_index = _cur_region_card_offset + _cur_card_in_prt;
 844   guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
 845             "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
 846   return true;
 847 }
 848 
 849 bool HeapRegionRemSetIterator::fine_has_next() {
 850   return _cur_card_in_prt != HeapRegion::CardsPerRegion;
 851 }
 852 
 853 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
 854   assert(prt != NULL, "Cannot switch to NULL prt");
 855   _fine_cur_prt = prt;
 856 
 857   HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
 858   _cur_region_card_offset = _bot->index_for(r_bot);
 859 
 860   // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
 861   // To avoid special-casing this start case, and not miss the first bitmap
 862   // entry, initialize _cur_region_cur_card with -1 instead of 0.
 863   _cur_card_in_prt = (size_t)-1;
 864 }
 865 
 866 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
 867   switch (_is) {
 868   case Sparse: {
 869     if (_sparse_iter.has_next(card_index)) {
 870       _n_yielded_sparse++;
 871       return true;
 872     }
 873     // Otherwise, deliberate fall-through
 874     _is = Fine;
 875     PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
 876     if (initial_fine_prt != NULL) {
 877       switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
 878     }
 879   }
 880   case Fine:
 881     if (fine_has_next(card_index)) {
 882       _n_yielded_fine++;
 883       return true;
 884     }
 885     // Otherwise, deliberate fall-through
 886     _is = Coarse;
 887   case Coarse:
 888     if (coarse_has_next(card_index)) {
 889       _n_yielded_coarse++;
 890       return true;
 891     }
 892     // Otherwise...
 893     break;
 894   }
 895   return false;
 896 }
 897 
 898 void HeapRegionRemSet::reset_for_cleanup_tasks() {
 899   SparsePRT::reset_for_cleanup_tasks();
 900 }
 901 
 902 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 903   _other_regions.do_cleanup_work(hrrs_cleanup_task);
 904 }
 905 
 906 void
 907 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
 908   SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
 909 }
 910 
 911 #ifndef PRODUCT
 912 void HeapRegionRemSet::test() {
 913   os::sleep(Thread::current(), (jlong)5000, false);
 914   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 915 
 916   // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
 917   // hash bucket.
 918   HeapRegion* hr0 = g1h->region_at(0);
 919   HeapRegion* hr1 = g1h->region_at(1);
 920   HeapRegion* hr2 = g1h->region_at(5);
 921   HeapRegion* hr3 = g1h->region_at(6);
 922   HeapRegion* hr4 = g1h->region_at(7);
 923   HeapRegion* hr5 = g1h->region_at(8);
 924 
 925   HeapWord* hr1_start = hr1->bottom();
 926   HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
 927   HeapWord* hr1_last = hr1->end() - 1;
 928 
 929   HeapWord* hr2_start = hr2->bottom();
 930   HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
 931   HeapWord* hr2_last = hr2->end() - 1;
 932 
 933   HeapWord* hr3_start = hr3->bottom();
 934   HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
 935   HeapWord* hr3_last = hr3->end() - 1;
 936 
 937   HeapRegionRemSet* hrrs = hr0->rem_set();
 938 
 939   // Make three references from region 0x101...
 940   hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
 941   hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
 942   hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
 943 
 944   hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
 945   hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
 946   hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
 947 
 948   hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
 949   hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
 950   hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
 951 
 952   // Now cause a coarsening.
 953   hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
 954   hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
 955 
 956   // Now, does iteration yield these three?
 957   HeapRegionRemSetIterator iter(hrrs);
 958   size_t sum = 0;
 959   size_t card_index;
 960   while (iter.has_next(card_index)) {
 961     HeapWord* card_start =
 962       G1CollectedHeap::heap()->bot()->address_for_index(card_index);
 963     tty->print_cr("  Card " PTR_FORMAT ".", p2i(card_start));
 964     sum++;
 965   }
 966   guarantee(sum == 11 - 3 + 2048, "Failure");
 967   guarantee(sum == hrrs->occupied(), "Failure");
 968 }
 969 #endif