changeset 26161:f75b959a3b46

Merge
author jmasa
date Tue, 19 Aug 2014 13:44:55 -0700
parents 983a1ebcc848 aba6b01cb988
children 8b27004a5786
files
diffstat 50 files changed, 2200 insertions(+), 1481 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1CollectedHeap.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1CollectedHeap.java	Tue Aug 19 13:44:55 2014 -0700
@@ -45,8 +45,8 @@
 public class G1CollectedHeap extends SharedHeap {
     // HeapRegionSeq _seq;
     static private long hrsFieldOffset;
-    // MemRegion _g1_committed;
-    static private long g1CommittedFieldOffset;
+    // MemRegion _g1_reserved;
+    static private long g1ReservedFieldOffset;
     // size_t _summary_bytes_used;
     static private CIntegerField summaryBytesUsedField;
     // G1MonitoringSupport* _g1mm;
@@ -68,7 +68,6 @@
         Type type = db.lookupType("G1CollectedHeap");
 
         hrsFieldOffset = type.getField("_hrs").getOffset();
-        g1CommittedFieldOffset = type.getField("_g1_committed").getOffset();
         summaryBytesUsedField = type.getCIntegerField("_summary_bytes_used");
         g1mmField = type.getAddressField("_g1mm");
         oldSetFieldOffset = type.getField("_old_set").getOffset();
@@ -76,9 +75,7 @@
     }
 
     public long capacity() {
-        Address g1CommittedAddr = addr.addOffsetTo(g1CommittedFieldOffset);
-        MemRegion g1Committed = new MemRegion(g1CommittedAddr);
-        return g1Committed.byteSize();
+        return hrs().capacity();
     }
 
     public long used() {
--- a/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1HeapRegionTable.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/G1HeapRegionTable.java	Tue Aug 19 13:44:55 2014 -0700
@@ -93,19 +93,35 @@
     private class HeapRegionIterator implements Iterator<HeapRegion> {
         private long index;
         private long length;
+        private HeapRegion next;
+
+        public HeapRegion positionToNext() {
+          HeapRegion result = next;
+          while (index < length && at(index) == null) {
+            index++;
+          }
+          if (index < length) {
+            next = at(index);
+            index++; // restart search at next element
+          } else {
+            next = null;
+          }
+          return result;
+        }
 
         @Override
-        public boolean hasNext() { return index < length; }
+        public boolean hasNext() { return next != null;     }
 
         @Override
-        public HeapRegion next() { return at(index++);    }
+        public HeapRegion next() { return positionToNext(); }
 
         @Override
-        public void remove()     { /* not supported */    }
+        public void remove()     { /* not supported */      }
 
-        HeapRegionIterator(long committedLength) {
+        HeapRegionIterator(long totalLength) {
             index = 0;
-            length = committedLength;
+            length = totalLength;
+            positionToNext();
         }
     }
 
--- a/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/HeapRegionSeq.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/agent/src/share/classes/sun/jvm/hotspot/gc_implementation/g1/HeapRegionSeq.java	Tue Aug 19 13:44:55 2014 -0700
@@ -43,7 +43,7 @@
     // G1HeapRegionTable _regions
     static private long regionsFieldOffset;
     // uint _committed_length
-    static private CIntegerField committedLengthField;
+    static private CIntegerField numCommittedField;
 
     static {
         VM.registerVMInitializedObserver(new Observer() {
@@ -57,7 +57,7 @@
         Type type = db.lookupType("HeapRegionSeq");
 
         regionsFieldOffset = type.getField("_regions").getOffset();
-        committedLengthField = type.getCIntegerField("_committed_length");
+        numCommittedField = type.getCIntegerField("_num_committed");
     }
 
     private G1HeapRegionTable regions() {
@@ -66,16 +66,20 @@
                                                              regionsAddr);
     }
 
+    public long capacity() {
+        return length() * HeapRegion.grainBytes();
+    }
+
     public long length() {
         return regions().length();
     }
 
     public long committedLength() {
-        return committedLengthField.getValue(addr);
+        return numCommittedField.getValue(addr);
     }
 
     public Iterator<HeapRegion> heapRegionIterator() {
-        return regions().heapRegionIterator(committedLength());
+        return regions().heapRegionIterator(length());
     }
 
     public HeapRegionSeq(Address addr) {
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -2734,10 +2734,12 @@
   }
 }
 
-void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
-  assert(fl->count() == 0, "Precondition.");
-  assert(word_sz < CompactibleFreeListSpace::IndexSetSize,
-         "Precondition");
+// Used by par_get_chunk_of_blocks() for the chunks from the
+// indexed_free_lists.  Looks for a chunk with size that is a multiple
+// of "word_sz" and if found, splits it into "word_sz" chunks and add
+// to the free list "fl".  "n" is the maximum number of chunks to
+// be added to "fl".
+bool CompactibleFreeListSpace:: par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
 
   // We'll try all multiples of word_sz in the indexed set, starting with
   // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples,
@@ -2818,11 +2820,15 @@
                         Mutex::_no_safepoint_check_flag);
         ssize_t births = _indexedFreeList[word_sz].split_births() + num;
         _indexedFreeList[word_sz].set_split_births(births);
-        return;
+        return true;
       }
     }
+    return found;
   }
-  // Otherwise, we'll split a block from the dictionary.
+}
+
+FreeChunk* CompactibleFreeListSpace::get_n_way_chunk_to_split(size_t word_sz, size_t n) {
+
   FreeChunk* fc = NULL;
   FreeChunk* rem_fc = NULL;
   size_t rem;
@@ -2833,16 +2839,12 @@
       fc = dictionary()->get_chunk(MAX2(n * word_sz, _dictionary->min_size()),
                                   FreeBlockDictionary<FreeChunk>::atLeast);
       if (fc != NULL) {
-        _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */);  // update _unallocated_blk
-        dictionary()->dict_census_update(fc->size(),
-                                       true /*split*/,
-                                       false /*birth*/);
         break;
       } else {
         n--;
       }
     }
-    if (fc == NULL) return;
+    if (fc == NULL) return NULL;
     // Otherwise, split up that block.
     assert((ssize_t)n >= 1, "Control point invariant");
     assert(fc->is_free(), "Error: should be a free block");
@@ -2864,10 +2866,14 @@
     // dictionary and return, leaving "fl" empty.
     if (n == 0) {
       returnChunkToDictionary(fc);
-      assert(fl->count() == 0, "We never allocated any blocks");
-      return;
+      return NULL;
     }
 
+    _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */);  // update _unallocated_blk
+    dictionary()->dict_census_update(fc->size(),
+                                     true /*split*/,
+                                     false /*birth*/);
+
     // First return the remainder, if any.
     // Note that we hold the lock until we decide if we're going to give
     // back the remainder to the dictionary, since a concurrent allocation
@@ -2900,7 +2906,24 @@
     _indexedFreeList[rem].return_chunk_at_head(rem_fc);
     smallSplitBirth(rem);
   }
-  assert((ssize_t)n > 0 && fc != NULL, "Consistency");
+  assert(n * word_sz == fc->size(),
+    err_msg("Chunk size " SIZE_FORMAT " is not exactly splittable by "
+    SIZE_FORMAT " sized chunks of size " SIZE_FORMAT,
+    fc->size(), n, word_sz));
+  return fc;
+}
+
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t targetted_number_of_chunks, AdaptiveFreeList<FreeChunk>* fl) {
+
+  FreeChunk* fc = get_n_way_chunk_to_split(word_sz, targetted_number_of_chunks);
+
+  if (fc == NULL) {
+    return;
+  }
+
+  size_t n = fc->size() / word_sz;
+
+  assert((ssize_t)n > 0, "Consistency");
   // Now do the splitting up.
   // Must do this in reverse order, so that anybody attempting to
   // access the main chunk sees it as a single free block until we
@@ -2948,6 +2971,20 @@
   assert(fl->tail()->next() == NULL, "List invariant.");
 }
 
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
+  assert(fl->count() == 0, "Precondition.");
+  assert(word_sz < CompactibleFreeListSpace::IndexSetSize,
+         "Precondition");
+
+  if (par_get_chunk_of_blocks_IFL(word_sz, n, fl)) {
+    // Got it
+    return;
+  }
+
+  // Otherwise, we'll split a block from the dictionary.
+  par_get_chunk_of_blocks_dictionary(word_sz, n, fl);
+}
+
 // Set up the space's par_seq_tasks structure for work claiming
 // for parallel rescan. See CMSParRemarkTask where this is currently used.
 // XXX Need to suitably abstract and generalize this and the next
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -172,6 +172,20 @@
   // list of size "word_sz", and must now be decremented.
   void par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
 
+  // Used by par_get_chunk_of_blocks() for the chunks from the
+  // indexed_free_lists.
+  bool par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
+
+  // Used by par_get_chunk_of_blocks_dictionary() to get a chunk
+  // evenly splittable into "n" "word_sz" chunks.  Returns that
+  // evenly splittable chunk.  May split a larger chunk to get the
+  // evenly splittable chunk.
+  FreeChunk* get_n_way_chunk_to_split(size_t word_sz, size_t n);
+
+  // Used by par_get_chunk_of_blocks() for the chunks from the
+  // dictionary.
+  void par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl);
+
   // Allocation helper functions
   // Allocate using a strategy that takes from the indexed free lists
   // first.  This allocation strategy assumes a companion sweeping
--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -81,8 +81,8 @@
   }
 }
 
-void ConcurrentG1Refine::init() {
-  _hot_card_cache.initialize();
+void ConcurrentG1Refine::init(G1RegionToSpaceMapper* card_counts_storage) {
+  _hot_card_cache.initialize(card_counts_storage);
 }
 
 void ConcurrentG1Refine::stop() {
--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -34,6 +34,7 @@
 class ConcurrentG1RefineThread;
 class G1CollectedHeap;
 class G1HotCardCache;
+class G1RegionToSpaceMapper;
 class G1RemSet;
 class DirtyCardQueue;
 
@@ -74,7 +75,7 @@
   ConcurrentG1Refine(G1CollectedHeap* g1h, CardTableEntryClosure* refine_closure);
   ~ConcurrentG1Refine();
 
-  void init(); // Accomplish some initialization that has to wait.
+  void init(G1RegionToSpaceMapper* card_counts_storage);
   void stop();
 
   void reinitialize_threads();
--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -36,6 +36,7 @@
 #include "gc_implementation/g1/heapRegion.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
+#include "gc_implementation/g1/heapRegionSet.inline.hpp"
 #include "gc_implementation/shared/vmGCOperations.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
@@ -99,12 +100,12 @@
 }
 
 #ifndef PRODUCT
-bool CMBitMapRO::covers(ReservedSpace heap_rs) const {
+bool CMBitMapRO::covers(MemRegion heap_rs) const {
   // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
   assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
          "size inconsistency");
-  return _bmStartWord == (HeapWord*)(heap_rs.base()) &&
-         _bmWordSize  == heap_rs.size()>>LogHeapWordSize;
+  return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
+         _bmWordSize  == heap_rs.word_size();
 }
 #endif
 
@@ -112,33 +113,73 @@
   _bm.print_on_error(st, prefix);
 }
 
-bool CMBitMap::allocate(ReservedSpace heap_rs) {
-  _bmStartWord = (HeapWord*)(heap_rs.base());
-  _bmWordSize  = heap_rs.size()/HeapWordSize;    // heap_rs.size() is in bytes
-  ReservedSpace brs(ReservedSpace::allocation_align_size_up(
-                     (_bmWordSize >> (_shifter + LogBitsPerByte)) + 1));
-  if (!brs.is_reserved()) {
-    warning("ConcurrentMark marking bit map allocation failure");
+size_t CMBitMap::compute_size(size_t heap_size) {
+  return heap_size / mark_distance();
+}
+
+size_t CMBitMap::mark_distance() {
+  return MinObjAlignmentInBytes * BitsPerByte;
+}
+
+void CMBitMap::initialize(MemRegion heap, G1RegionToSpaceMapper* storage) {
+  _bmStartWord = heap.start();
+  _bmWordSize = heap.word_size();
+
+  _bm.set_map((BitMap::bm_word_t*) storage->reserved().start());
+  _bm.set_size(_bmWordSize >> _shifter);
+
+  storage->set_mapping_changed_listener(&_listener);
+}
+
+void CMBitMapMappingChangedListener::on_commit(uint start_region, size_t num_regions) {
+  // We need to clear the bitmap on commit, removing any existing information.
+  MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_region), num_regions * HeapRegion::GrainWords);
+  _bm->clearRange(mr);
+}
+
+// Closure used for clearing the given mark bitmap.
+class ClearBitmapHRClosure : public HeapRegionClosure {
+ private:
+  ConcurrentMark* _cm;
+  CMBitMap* _bitmap;
+  bool _may_yield;      // The closure may yield during iteration. If yielded, abort the iteration.
+ public:
+  ClearBitmapHRClosure(ConcurrentMark* cm, CMBitMap* bitmap, bool may_yield) : HeapRegionClosure(), _cm(cm), _bitmap(bitmap), _may_yield(may_yield) {
+    assert(!may_yield || cm != NULL, "CM must be non-NULL if this closure is expected to yield.");
+  }
+
+  virtual bool doHeapRegion(HeapRegion* r) {
+    size_t const chunk_size_in_words = M / HeapWordSize;
+
+    HeapWord* cur = r->bottom();
+    HeapWord* const end = r->end();
+
+    while (cur < end) {
+      MemRegion mr(cur, MIN2(cur + chunk_size_in_words, end));
+      _bitmap->clearRange(mr);
+
+      cur += chunk_size_in_words;
+
+      // Abort iteration if after yielding the marking has been aborted.
+      if (_may_yield && _cm->do_yield_check() && _cm->has_aborted()) {
+        return true;
+      }
+      // Repeat the asserts from before the start of the closure. We will do them
+      // as asserts here to minimize their overhead on the product. However, we
+      // will have them as guarantees at the beginning / end of the bitmap
+      // clearing to get some checking in the product.
+      assert(!_may_yield || _cm->cmThread()->during_cycle(), "invariant");
+      assert(!_may_yield || !G1CollectedHeap::heap()->mark_in_progress(), "invariant");
+    }
+
     return false;
   }
-  MemTracker::record_virtual_memory_type((address)brs.base(), mtGC);
-  // For now we'll just commit all of the bit map up front.
-  // Later on we'll try to be more parsimonious with swap.
-  if (!_virtual_space.initialize(brs, brs.size())) {
-    warning("ConcurrentMark marking bit map backing store failure");
-    return false;
-  }
-  assert(_virtual_space.committed_size() == brs.size(),
-         "didn't reserve backing store for all of concurrent marking bit map?");
-  _bm.set_map((BitMap::bm_word_t*)_virtual_space.low());
-  assert(_virtual_space.committed_size() << (_shifter + LogBitsPerByte) >=
-         _bmWordSize, "inconsistency in bit map sizing");
-  _bm.set_size(_bmWordSize >> _shifter);
-  return true;
-}
+};
 
 void CMBitMap::clearAll() {
-  _bm.clear();
+  ClearBitmapHRClosure cl(NULL, this, false /* may_yield */);
+  G1CollectedHeap::heap()->heap_region_iterate(&cl);
+  guarantee(cl.complete(), "Must have completed iteration.");
   return;
 }
 
@@ -483,10 +524,10 @@
   return MAX2((n_par_threads + 2) / 4, 1U);
 }
 
-ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs) :
+ConcurrentMark::ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage) :
   _g1h(g1h),
-  _markBitMap1(log2_intptr(MinObjAlignment)),
-  _markBitMap2(log2_intptr(MinObjAlignment)),
+  _markBitMap1(),
+  _markBitMap2(),
   _parallel_marking_threads(0),
   _max_parallel_marking_threads(0),
   _sleep_factor(0.0),
@@ -495,7 +536,7 @@
   _cleanup_task_overhead(1.0),
   _cleanup_list("Cleanup List"),
   _region_bm((BitMap::idx_t)(g1h->max_regions()), false /* in_resource_area*/),
-  _card_bm((heap_rs.size() + CardTableModRefBS::card_size - 1) >>
+  _card_bm((g1h->reserved_region().byte_size() + CardTableModRefBS::card_size - 1) >>
             CardTableModRefBS::card_shift,
             false /* in_resource_area*/),
 
@@ -545,14 +586,8 @@
                            "heap end = " PTR_FORMAT, p2i(_heap_start), p2i(_heap_end));
   }
 
-  if (!_markBitMap1.allocate(heap_rs)) {
-    warning("Failed to allocate first CM bit map");
-    return;
-  }
-  if (!_markBitMap2.allocate(heap_rs)) {
-    warning("Failed to allocate second CM bit map");
-    return;
-  }
+  _markBitMap1.initialize(g1h->reserved_region(), prev_bitmap_storage);
+  _markBitMap2.initialize(g1h->reserved_region(), next_bitmap_storage);
 
   // Create & start a ConcurrentMark thread.
   _cmThread = new ConcurrentMarkThread(this);
@@ -563,8 +598,8 @@
   }
 
   assert(CGC_lock != NULL, "Where's the CGC_lock?");
-  assert(_markBitMap1.covers(heap_rs), "_markBitMap1 inconsistency");
-  assert(_markBitMap2.covers(heap_rs), "_markBitMap2 inconsistency");
+  assert(_markBitMap1.covers(g1h->reserved_region()), "_markBitMap1 inconsistency");
+  assert(_markBitMap2.covers(g1h->reserved_region()), "_markBitMap2 inconsistency");
 
   SATBMarkQueueSet& satb_qs = JavaThread::satb_mark_queue_set();
   satb_qs.set_buffer_size(G1SATBBufferSize);
@@ -724,38 +759,17 @@
   clear_all_count_data();
 
   // so that the call below can read a sensible value
-  _heap_start = (HeapWord*) heap_rs.base();
+  _heap_start = g1h->reserved_region().start();
   set_non_marking_state();
   _completed_initialization = true;
 }
 
-void ConcurrentMark::update_g1_committed(bool force) {
-  // If concurrent marking is not in progress, then we do not need to
-  // update _heap_end.
-  if (!concurrent_marking_in_progress() && !force) return;
-
-  MemRegion committed = _g1h->g1_committed();
-  assert(committed.start() == _heap_start, "start shouldn't change");
-  HeapWord* new_end = committed.end();
-  if (new_end > _heap_end) {
-    // The heap has been expanded.
-
-    _heap_end = new_end;
-  }
-  // Notice that the heap can also shrink. However, this only happens
-  // during a Full GC (at least currently) and the entire marking
-  // phase will bail out and the task will not be restarted. So, let's
-  // do nothing.
-}
-
 void ConcurrentMark::reset() {
   // Starting values for these two. This should be called in a STW
-  // phase. CM will be notified of any future g1_committed expansions
-  // will be at the end of evacuation pauses, when tasks are
-  // inactive.
-  MemRegion committed = _g1h->g1_committed();
-  _heap_start = committed.start();
-  _heap_end   = committed.end();
+  // phase.
+  MemRegion reserved = _g1h->g1_reserved();
+  _heap_start = reserved.start();
+  _heap_end   = reserved.end();
 
   // Separated the asserts so that we know which one fires.
   assert(_heap_start != NULL, "heap bounds should look ok");
@@ -827,7 +841,6 @@
     assert(out_of_regions(),
            err_msg("only way to get here: _finger: "PTR_FORMAT", _heap_end: "PTR_FORMAT,
                    p2i(_finger), p2i(_heap_end)));
-    update_g1_committed(true);
   }
 }
 
@@ -846,7 +859,6 @@
 
 void ConcurrentMark::clearNextBitmap() {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  G1CollectorPolicy* g1p = g1h->g1_policy();
 
   // Make sure that the concurrent mark thread looks to still be in
   // the current cycle.
@@ -858,41 +870,36 @@
   // is the case.
   guarantee(!g1h->mark_in_progress(), "invariant");
 
-  // clear the mark bitmap (no grey objects to start with).
-  // We need to do this in chunks and offer to yield in between
-  // each chunk.
-  HeapWord* start  = _nextMarkBitMap->startWord();
-  HeapWord* end    = _nextMarkBitMap->endWord();
-  HeapWord* cur    = start;
-  size_t chunkSize = M;
-  while (cur < end) {
-    HeapWord* next = cur + chunkSize;
-    if (next > end) {
-      next = end;
-    }
-    MemRegion mr(cur,next);
-    _nextMarkBitMap->clearRange(mr);
-    cur = next;
-    do_yield_check();
-
-    // Repeat the asserts from above. We'll do them as asserts here to
-    // minimize their overhead on the product. However, we'll have
-    // them as guarantees at the beginning / end of the bitmap
-    // clearing to get some checking in the product.
-    assert(cmThread()->during_cycle(), "invariant");
-    assert(!g1h->mark_in_progress(), "invariant");
+  ClearBitmapHRClosure cl(this, _nextMarkBitMap, true /* may_yield */);
+  g1h->heap_region_iterate(&cl);
+
+  // Clear the liveness counting data. If the marking has been aborted, the abort()
+  // call already did that.
+  if (cl.complete()) {
+    clear_all_count_data();
   }
 
-  // Clear the liveness counting data
-  clear_all_count_data();
-
   // Repeat the asserts from above.
   guarantee(cmThread()->during_cycle(), "invariant");
   guarantee(!g1h->mark_in_progress(), "invariant");
 }
 
+class CheckBitmapClearHRClosure : public HeapRegionClosure {
+  CMBitMap* _bitmap;
+  bool _error;
+ public:
+  CheckBitmapClearHRClosure(CMBitMap* bitmap) : _bitmap(bitmap) {
+  }
+
+  virtual bool doHeapRegion(HeapRegion* r) {
+    return _bitmap->getNextMarkedWordAddress(r->bottom(), r->end()) != r->end();
+  }
+};
+
 bool ConcurrentMark::nextMarkBitmapIsClear() {
-  return _nextMarkBitMap->getNextMarkedWordAddress(_heap_start, _heap_end) == _heap_end;
+  CheckBitmapClearHRClosure cl(_nextMarkBitMap);
+  _g1h->heap_region_iterate(&cl);
+  return cl.complete();
 }
 
 class NoteStartOfMarkHRClosure: public HeapRegionClosure {
@@ -2193,10 +2200,10 @@
                            _cleanup_list.length());
   }
 
-  // Noone else should be accessing the _cleanup_list at this point,
-  // so it's not necessary to take any locks
+  // No one else should be accessing the _cleanup_list at this point,
+  // so it is not necessary to take any locks
   while (!_cleanup_list.is_empty()) {
-    HeapRegion* hr = _cleanup_list.remove_head();
+    HeapRegion* hr = _cleanup_list.remove_region(true /* from_head */);
     assert(hr != NULL, "Got NULL from a non-empty list");
     hr->par_clear();
     tmp_free_list.add_ordered(hr);
@@ -2980,22 +2987,25 @@
     // claim_region() and a humongous object allocation might force us
     // to do a bit of unnecessary work (due to some unnecessary bitmap
     // iterations) but it should not introduce and correctness issues.
-    HeapRegion* curr_region   = _g1h->heap_region_containing_raw(finger);
-    HeapWord*   bottom        = curr_region->bottom();
-    HeapWord*   end           = curr_region->end();
-    HeapWord*   limit         = curr_region->next_top_at_mark_start();
-
-    if (verbose_low()) {
-      gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
-                             "["PTR_FORMAT", "PTR_FORMAT"), "
-                             "limit = "PTR_FORMAT,
-                             worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
-    }
+    HeapRegion* curr_region = _g1h->heap_region_containing_raw(finger);
+
+    // Above heap_region_containing_raw may return NULL as we always scan claim
+    // until the end of the heap. In this case, just jump to the next region.
+    HeapWord* end = curr_region != NULL ? curr_region->end() : finger + HeapRegion::GrainWords;
 
     // Is the gap between reading the finger and doing the CAS too long?
     HeapWord* res = (HeapWord*) Atomic::cmpxchg_ptr(end, &_finger, finger);
-    if (res == finger) {
+    if (res == finger && curr_region != NULL) {
       // we succeeded
+      HeapWord*   bottom        = curr_region->bottom();
+      HeapWord*   limit         = curr_region->next_top_at_mark_start();
+
+      if (verbose_low()) {
+        gclog_or_tty->print_cr("[%u] curr_region = "PTR_FORMAT" "
+                               "["PTR_FORMAT", "PTR_FORMAT"), "
+                               "limit = "PTR_FORMAT,
+                               worker_id, p2i(curr_region), p2i(bottom), p2i(end), p2i(limit));
+      }
 
       // notice that _finger == end cannot be guaranteed here since,
       // someone else might have moved the finger even further
@@ -3026,10 +3036,17 @@
     } else {
       assert(_finger > finger, "the finger should have moved forward");
       if (verbose_low()) {
-        gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
-                               "global finger = "PTR_FORMAT", "
-                               "our finger = "PTR_FORMAT,
-                               worker_id, p2i(_finger), p2i(finger));
+        if (curr_region == NULL) {
+          gclog_or_tty->print_cr("[%u] found uncommitted region, moving finger, "
+                                 "global finger = "PTR_FORMAT", "
+                                 "our finger = "PTR_FORMAT,
+                                 worker_id, p2i(_finger), p2i(finger));
+        } else {
+          gclog_or_tty->print_cr("[%u] somebody else moved the finger, "
+                                 "global finger = "PTR_FORMAT", "
+                                 "our finger = "PTR_FORMAT,
+                                 worker_id, p2i(_finger), p2i(finger));
+        }
       }
 
       // read it again
@@ -3144,8 +3161,10 @@
       // happens, heap_region_containing() will return the bottom of the
       // corresponding starts humongous region and the check below will
       // not hold any more.
+      // Since we always iterate over all regions, we might get a NULL HeapRegion
+      // here.
       HeapRegion* global_hr = _g1h->heap_region_containing_raw(global_finger);
-      guarantee(global_finger == global_hr->bottom(),
+      guarantee(global_hr == NULL || global_finger == global_hr->bottom(),
                 err_msg("global finger: "PTR_FORMAT" region: "HR_FORMAT,
                         p2i(global_finger), HR_FORMAT_PARAMS(global_hr)));
     }
@@ -3158,7 +3177,7 @@
       if (task_finger != NULL && task_finger < _heap_end) {
         // See above note on the global finger verification.
         HeapRegion* task_hr = _g1h->heap_region_containing_raw(task_finger);
-        guarantee(task_finger == task_hr->bottom() ||
+        guarantee(task_hr == NULL || task_finger == task_hr->bottom() ||
                   !task_hr->in_collection_set(),
                   err_msg("task finger: "PTR_FORMAT" region: "HR_FORMAT,
                           p2i(task_finger), HR_FORMAT_PARAMS(task_hr)));
@@ -4674,7 +4693,6 @@
     _hum_prev_live_bytes(0), _hum_next_live_bytes(0),
     _total_remset_bytes(0), _total_strong_code_roots_bytes(0) {
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  MemRegion g1_committed = g1h->g1_committed();
   MemRegion g1_reserved = g1h->g1_reserved();
   double now = os::elapsedTime();
 
@@ -4682,10 +4700,8 @@
   _out->cr();
   _out->print_cr(G1PPRL_LINE_PREFIX" PHASE %s @ %1.3f", phase_name, now);
   _out->print_cr(G1PPRL_LINE_PREFIX" HEAP"
-                 G1PPRL_SUM_ADDR_FORMAT("committed")
                  G1PPRL_SUM_ADDR_FORMAT("reserved")
                  G1PPRL_SUM_BYTE_FORMAT("region-size"),
-                 p2i(g1_committed.start()), p2i(g1_committed.end()),
                  p2i(g1_reserved.start()), p2i(g1_reserved.end()),
                  HeapRegion::GrainBytes);
   _out->print_cr(G1PPRL_LINE_PREFIX);
--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -27,10 +27,12 @@
 
 #include "classfile/javaClasses.hpp"
 #include "gc_implementation/g1/heapRegionSet.hpp"
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "gc_implementation/shared/gcId.hpp"
 #include "utilities/taskqueue.hpp"
 
 class G1CollectedHeap;
+class CMBitMap;
 class CMTask;
 typedef GenericTaskQueue<oop, mtGC>            CMTaskQueue;
 typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
@@ -57,7 +59,6 @@
   HeapWord* _bmStartWord;      // base address of range covered by map
   size_t    _bmWordSize;       // map size (in #HeapWords covered)
   const int _shifter;          // map to char or bit
-  VirtualSpace _virtual_space; // underlying the bit map
   BitMap    _bm;               // the bit map itself
 
  public:
@@ -115,42 +116,41 @@
   void print_on_error(outputStream* st, const char* prefix) const;
 
   // debugging
-  NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
+  NOT_PRODUCT(bool covers(MemRegion rs) const;)
+};
+
+class CMBitMapMappingChangedListener : public G1MappingChangedListener {
+ private:
+  CMBitMap* _bm;
+ public:
+  CMBitMapMappingChangedListener() : _bm(NULL) {}
+
+  void set_bitmap(CMBitMap* bm) { _bm = bm; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions);
 };
 
 class CMBitMap : public CMBitMapRO {
+ private:
+  CMBitMapMappingChangedListener _listener;
 
  public:
-  // constructor
-  CMBitMap(int shifter) :
-    CMBitMapRO(shifter) {}
+  static size_t compute_size(size_t heap_size);
+  // Returns the amount of bytes on the heap between two marks in the bitmap.
+  static size_t mark_distance();
 
-  // Allocates the back store for the marking bitmap
-  bool allocate(ReservedSpace heap_rs);
+  CMBitMap() : CMBitMapRO(LogMinObjAlignment), _listener() { _listener.set_bitmap(this); }
 
-  // write marks
-  void mark(HeapWord* addr) {
-    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
-           "outside underlying space?");
-    _bm.set_bit(heapWordToOffset(addr));
-  }
-  void clear(HeapWord* addr) {
-    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
-           "outside underlying space?");
-    _bm.clear_bit(heapWordToOffset(addr));
-  }
-  bool parMark(HeapWord* addr) {
-    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
-           "outside underlying space?");
-    return _bm.par_set_bit(heapWordToOffset(addr));
-  }
-  bool parClear(HeapWord* addr) {
-    assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
-           "outside underlying space?");
-    return _bm.par_clear_bit(heapWordToOffset(addr));
-  }
+  // Initializes the underlying BitMap to cover the given area.
+  void initialize(MemRegion heap, G1RegionToSpaceMapper* storage);
+
+  // Write marks.
+  inline void mark(HeapWord* addr);
+  inline void clear(HeapWord* addr);
+  inline bool parMark(HeapWord* addr);
+  inline bool parClear(HeapWord* addr);
+
   void markRange(MemRegion mr);
-  void clearAll();
   void clearRange(MemRegion mr);
 
   // Starting at the bit corresponding to "addr" (inclusive), find the next
@@ -161,6 +161,9 @@
   // the run.  If there is no "1" bit at or after "addr", return an empty
   // MemRegion.
   MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
+
+  // Clear the whole mark bitmap.
+  void clearAll();
 };
 
 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
@@ -680,7 +683,7 @@
     return _task_queues->steal(worker_id, hash_seed, obj);
   }
 
-  ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs);
+  ConcurrentMark(G1CollectedHeap* g1h, G1RegionToSpaceMapper* prev_bitmap_storage, G1RegionToSpaceMapper* next_bitmap_storage);
   ~ConcurrentMark();
 
   ConcurrentMarkThread* cmThread() { return _cmThread; }
@@ -736,7 +739,8 @@
   // Clear the next marking bitmap (will be called concurrently).
   void clearNextBitmap();
 
-  // Return whether the next mark bitmap has no marks set.
+  // Return whether the next mark bitmap has no marks set. To be used for assertions
+  // only. Will not yield to pause requests.
   bool nextMarkBitmapIsClear();
 
   // These two do the work that needs to be done before and after the
@@ -794,12 +798,6 @@
                            bool verify_thread_buffers,
                            bool verify_fingers) PRODUCT_RETURN;
 
-  // It is called at the end of an evacuation pause during marking so
-  // that CM is notified of where the new end of the heap is. It
-  // doesn't do anything if concurrent_marking_in_progress() is false,
-  // unless the force parameter is true.
-  void update_g1_committed(bool force = false);
-
   bool isMarked(oop p) const {
     assert(p != NULL && p->is_oop(), "expected an oop");
     HeapWord* addr = (HeapWord*)p;
--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -268,6 +268,36 @@
   return iterate(cl, mr);
 }
 
+#define check_mark(addr)                                                       \
+  assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize),      \
+         "outside underlying space?");                                         \
+  assert(G1CollectedHeap::heap()->is_in_exact(addr),                           \
+         err_msg("Trying to access not available bitmap "PTR_FORMAT            \
+                 " corresponding to "PTR_FORMAT" (%u)",                        \
+                 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr)));
+
+inline void CMBitMap::mark(HeapWord* addr) {
+  check_mark(addr);
+  _bm.set_bit(heapWordToOffset(addr));
+}
+
+inline void CMBitMap::clear(HeapWord* addr) {
+  check_mark(addr);
+  _bm.clear_bit(heapWordToOffset(addr));
+}
+
+inline bool CMBitMap::parMark(HeapWord* addr) {
+  check_mark(addr);
+  return _bm.par_set_bit(heapWordToOffset(addr));
+}
+
+inline bool CMBitMap::parClear(HeapWord* addr) {
+  check_mark(addr);
+  return _bm.par_clear_bit(heapWordToOffset(addr));
+}
+
+#undef check_mark
+
 inline void CMTask::push(oop obj) {
   HeapWord* objAddr = (HeapWord*) obj;
   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
--- a/hotspot/src/share/vm/gc_implementation/g1/g1AllocRegion.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1AllocRegion.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -173,7 +173,7 @@
 
   // Should be called when we want to release the active region which
   // is returned after it's been retired.
-  HeapRegion* release();
+  virtual HeapRegion* release();
 
 #if G1_ALLOC_REGION_TRACING
   void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
--- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -32,64 +32,37 @@
 
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 
+void G1BlockOffsetSharedArrayMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
+  // Nothing to do. The BOT is hard-wired to be part of the HeapRegion, and we cannot
+  // retrieve it here since this would cause firing of several asserts. The code
+  // executed after commit of a region already needs to do some re-initialization of
+  // the HeapRegion, so we combine that.
+}
+
 //////////////////////////////////////////////////////////////////////
 // G1BlockOffsetSharedArray
 //////////////////////////////////////////////////////////////////////
 
-G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion reserved,
-                                                   size_t init_word_size) :
-  _reserved(reserved), _end(NULL)
-{
-  size_t size = compute_size(reserved.word_size());
-  ReservedSpace rs(ReservedSpace::allocation_align_size_up(size));
-  if (!rs.is_reserved()) {
-    vm_exit_during_initialization("Could not reserve enough space for heap offset array");
-  }
-  if (!_vs.initialize(rs, 0)) {
-    vm_exit_during_initialization("Could not reserve enough space for heap offset array");
-  }
+G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage) :
+  _reserved(), _end(NULL), _listener(), _offset_array(NULL) {
 
-  MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
+  _reserved = heap;
+  _end = NULL;
 
-  _offset_array = (u_char*)_vs.low_boundary();
-  resize(init_word_size);
+  MemRegion bot_reserved = storage->reserved();
+
+  _offset_array = (u_char*)bot_reserved.start();
+  _end = _reserved.end();
+
+  storage->set_mapping_changed_listener(&_listener);
+
   if (TraceBlockOffsetTable) {
     gclog_or_tty->print_cr("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: ");
     gclog_or_tty->print_cr("  "
                   "  rs.base(): " INTPTR_FORMAT
                   "  rs.size(): " INTPTR_FORMAT
                   "  rs end(): " INTPTR_FORMAT,
-                  rs.base(), rs.size(), rs.base() + rs.size());
-    gclog_or_tty->print_cr("  "
-                  "  _vs.low_boundary(): " INTPTR_FORMAT
-                  "  _vs.high_boundary(): " INTPTR_FORMAT,
-                  _vs.low_boundary(),
-                  _vs.high_boundary());
-  }
-}
-
-void G1BlockOffsetSharedArray::resize(size_t new_word_size) {
-  assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved");
-  size_t new_size = compute_size(new_word_size);
-  size_t old_size = _vs.committed_size();
-  size_t delta;
-  char* high = _vs.high();
-  _end = _reserved.start() + new_word_size;
-  if (new_size > old_size) {
-    delta = ReservedSpace::page_align_size_up(new_size - old_size);
-    assert(delta > 0, "just checking");
-    if (!_vs.expand_by(delta)) {
-      // Do better than this for Merlin
-      vm_exit_out_of_memory(delta, OOM_MMAP_ERROR, "offset table expansion");
-    }
-    assert(_vs.high() == high + delta, "invalid expansion");
-    // Initialization of the contents is left to the
-    // G1BlockOffsetArray that uses it.
-  } else {
-    delta = ReservedSpace::page_align_size_down(old_size - new_size);
-    if (delta == 0) return;
-    _vs.shrink_by(delta);
-    assert(_vs.high() == high - delta, "invalid expansion");
+                  bot_reserved.start(), bot_reserved.byte_size(), bot_reserved.end());
   }
 }
 
@@ -100,18 +73,7 @@
 }
 
 void G1BlockOffsetSharedArray::set_offset_array(HeapWord* left, HeapWord* right, u_char offset) {
-  check_index(index_for(right - 1), "right address out of range");
-  assert(left  < right, "Heap addresses out of order");
-  size_t num_cards = pointer_delta(right, left) >> LogN_words;
-  if (UseMemSetInBOT) {
-    memset(&_offset_array[index_for(left)], offset, num_cards);
-  } else {
-    size_t i = index_for(left);
-    const size_t end = i + num_cards;
-    for (; i < end; i++) {
-      _offset_array[i] = offset;
-    }
-  }
+  set_offset_array(index_for(left), index_for(right -1), offset);
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -650,6 +612,25 @@
   _next_offset_index = 0;
 }
 
+HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold_raw() {
+  assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+         "just checking");
+  _next_offset_index = _array->index_for_raw(_bottom);
+  _next_offset_index++;
+  _next_offset_threshold =
+    _array->address_for_index_raw(_next_offset_index);
+  return _next_offset_threshold;
+}
+
+void G1BlockOffsetArrayContigSpace::zero_bottom_entry_raw() {
+  assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
+         "just checking");
+  size_t bottom_index = _array->index_for_raw(_bottom);
+  assert(_array->address_for_index_raw(bottom_index) == _bottom,
+         "Precondition of call");
+  _array->set_offset_array_raw(bottom_index, 0);
+}
+
 HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() {
   assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
          "just checking");
@@ -674,8 +655,7 @@
   assert(new_top <= _end, "_end should have already been updated");
 
   // The first BOT entry should have offset 0.
-  zero_bottom_entry();
-  initialize_threshold();
+  reset_bot();
   alloc_block(_bottom, new_top);
  }
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1BLOCKOFFSETTABLE_HPP
 
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "memory/memRegion.hpp"
 #include "runtime/virtualspace.hpp"
 #include "utilities/globalDefinitions.hpp"
@@ -106,6 +107,11 @@
   inline HeapWord* block_start_const(const void* addr) const;
 };
 
+class G1BlockOffsetSharedArrayMappingChangedListener : public G1MappingChangedListener {
+ public:
+  virtual void on_commit(uint start_idx, size_t num_regions);
+};
+
 // This implementation of "G1BlockOffsetTable" divides the covered region
 // into "N"-word subregions (where "N" = 2^"LogN".  An array with an entry
 // for each such subregion indicates how far back one must go to find the
@@ -125,6 +131,7 @@
   friend class VMStructs;
 
 private:
+  G1BlockOffsetSharedArrayMappingChangedListener _listener;
   // The reserved region covered by the shared array.
   MemRegion _reserved;
 
@@ -133,16 +140,8 @@
 
   // Array for keeping offsets for retrieving object start fast given an
   // address.
-  VirtualSpace _vs;
   u_char* _offset_array;          // byte array keeping backwards offsets
 
-  void check_index(size_t index, const char* msg) const {
-    assert(index < _vs.committed_size(),
-           err_msg("%s - "
-                   "index: " SIZE_FORMAT ", _vs.committed_size: " SIZE_FORMAT,
-                   msg, index, _vs.committed_size()));
-  }
-
   void check_offset(size_t offset, const char* msg) const {
     assert(offset <= N_words,
            err_msg("%s - "
@@ -152,63 +151,33 @@
 
   // Bounds checking accessors:
   // For performance these have to devolve to array accesses in product builds.
-  u_char offset_array(size_t index) const {
-    check_index(index, "index out of range");
-    return _offset_array[index];
-  }
+  inline u_char offset_array(size_t index) const;
 
   void set_offset_array(HeapWord* left, HeapWord* right, u_char offset);
 
-  void set_offset_array(size_t index, u_char offset) {
-    check_index(index, "index out of range");
-    check_offset(offset, "offset too large");
+  void set_offset_array_raw(size_t index, u_char offset) {
     _offset_array[index] = offset;
   }
 
-  void set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
-    check_index(index, "index out of range");
-    assert(high >= low, "addresses out of order");
-    check_offset(pointer_delta(high, low), "offset too large");
-    _offset_array[index] = (u_char) pointer_delta(high, low);
-  }
+  inline void set_offset_array(size_t index, u_char offset);
 
-  void set_offset_array(size_t left, size_t right, u_char offset) {
-    check_index(right, "right index out of range");
-    assert(left <= right, "indexes out of order");
-    size_t num_cards = right - left + 1;
-    if (UseMemSetInBOT) {
-      memset(&_offset_array[left], offset, num_cards);
-    } else {
-      size_t i = left;
-      const size_t end = i + num_cards;
-      for (; i < end; i++) {
-        _offset_array[i] = offset;
-      }
-    }
-  }
+  inline void set_offset_array(size_t index, HeapWord* high, HeapWord* low);
 
-  void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const {
-    check_index(index, "index out of range");
-    assert(high >= low, "addresses out of order");
-    check_offset(pointer_delta(high, low), "offset too large");
-    assert(_offset_array[index] == pointer_delta(high, low), "Wrong offset");
-  }
+  inline void set_offset_array(size_t left, size_t right, u_char offset);
+
+  inline void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const;
 
   bool is_card_boundary(HeapWord* p) const;
 
+public:
+
   // Return the number of slots needed for an offset array
   // that covers mem_region_words words.
-  // We always add an extra slot because if an object
-  // ends on a card boundary we put a 0 in the next
-  // offset array slot, so we want that slot always
-  // to be reserved.
-
-  size_t compute_size(size_t mem_region_words) {
-    size_t number_of_slots = (mem_region_words / N_words) + 1;
-    return ReservedSpace::page_align_size_up(number_of_slots);
+  static size_t compute_size(size_t mem_region_words) {
+    size_t number_of_slots = (mem_region_words / N_words);
+    return ReservedSpace::allocation_align_size_up(number_of_slots);
   }
 
-public:
   enum SomePublicConstants {
     LogN = 9,
     LogN_words = LogN - LogHeapWordSize,
@@ -222,25 +191,21 @@
   // least "init_word_size".) The contents of the initial table are
   // undefined; it is the responsibility of the constituent
   // G1BlockOffsetTable(s) to initialize cards.
-  G1BlockOffsetSharedArray(MemRegion reserved, size_t init_word_size);
-
-  // Notes a change in the committed size of the region covered by the
-  // table.  The "new_word_size" may not be larger than the size of the
-  // reserved region this table covers.
-  void resize(size_t new_word_size);
+  G1BlockOffsetSharedArray(MemRegion heap, G1RegionToSpaceMapper* storage);
 
   void set_bottom(HeapWord* new_bottom);
 
-  // Updates all the BlockOffsetArray's sharing this shared array to
-  // reflect the current "top"'s of their spaces.
-  void update_offset_arrays();
-
   // Return the appropriate index into "_offset_array" for "p".
   inline size_t index_for(const void* p) const;
+  inline size_t index_for_raw(const void* p) const;
 
   // Return the address indicating the start of the region corresponding to
   // "index" in "_offset_array".
   inline HeapWord* address_for_index(size_t index) const;
+  // Variant of address_for_index that does not check the index for validity.
+  inline HeapWord* address_for_index_raw(size_t index) const {
+    return _reserved.start() + (index << LogN_words);
+  }
 };
 
 // And here is the G1BlockOffsetTable subtype that uses the array.
@@ -480,6 +445,14 @@
                       blk_start, blk_end);
   }
 
+  // Variant of zero_bottom_entry that does not check for availability of the
+  // memory first.
+  void zero_bottom_entry_raw();
+  // Variant of initialize_threshold that does not check for availability of the
+  // memory first.
+  HeapWord* initialize_threshold_raw();
+  // Zero out the entry for _bottom (offset will be zero).
+  void zero_bottom_entry();
  public:
   G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, MemRegion mr);
 
@@ -487,8 +460,10 @@
   // bottom of the covered region.
   HeapWord* initialize_threshold();
 
-  // Zero out the entry for _bottom (offset will be zero).
-  void      zero_bottom_entry();
+  void reset_bot() {
+    zero_bottom_entry_raw();
+    initialize_threshold_raw();
+  }
 
   // Return the next threshold, the point at which the table should be
   // updated.
--- a/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.inline.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -47,14 +47,69 @@
   }
 }
 
+#define check_index(index, msg)                                                \
+  assert((index) < (_reserved.word_size() >> LogN_words),                      \
+         err_msg("%s - index: "SIZE_FORMAT", _vs.committed_size: "SIZE_FORMAT, \
+                 msg, (index), (_reserved.word_size() >> LogN_words)));        \
+  assert(G1CollectedHeap::heap()->is_in_exact(address_for_index_raw(index)),   \
+         err_msg("Index "SIZE_FORMAT" corresponding to "PTR_FORMAT             \
+                 " (%u) is not in committed area.",                            \
+                 (index),                                                      \
+                 p2i(address_for_index_raw(index)),                            \
+                 G1CollectedHeap::heap()->addr_to_region(address_for_index_raw(index))));
+
+u_char G1BlockOffsetSharedArray::offset_array(size_t index) const {
+  check_index(index, "index out of range");
+  return _offset_array[index];
+}
+
+void G1BlockOffsetSharedArray::set_offset_array(size_t index, u_char offset) {
+  check_index(index, "index out of range");
+  set_offset_array_raw(index, offset);
+}
+
+void G1BlockOffsetSharedArray::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
+  check_index(index, "index out of range");
+  assert(high >= low, "addresses out of order");
+  size_t offset = pointer_delta(high, low);
+  check_offset(offset, "offset too large");
+  set_offset_array(index, (u_char)offset);
+}
+
+void G1BlockOffsetSharedArray::set_offset_array(size_t left, size_t right, u_char offset) {
+  check_index(right, "right index out of range");
+  assert(left <= right, "indexes out of order");
+  size_t num_cards = right - left + 1;
+  if (UseMemSetInBOT) {
+    memset(&_offset_array[left], offset, num_cards);
+  } else {
+    size_t i = left;
+    const size_t end = i + num_cards;
+    for (; i < end; i++) {
+      _offset_array[i] = offset;
+    }
+  }
+}
+
+void G1BlockOffsetSharedArray::check_offset_array(size_t index, HeapWord* high, HeapWord* low) const {
+  check_index(index, "index out of range");
+  assert(high >= low, "addresses out of order");
+  check_offset(pointer_delta(high, low), "offset too large");
+  assert(_offset_array[index] == pointer_delta(high, low), "Wrong offset");
+}
+
+// Variant of index_for that does not check the index for validity.
+inline size_t G1BlockOffsetSharedArray::index_for_raw(const void* p) const {
+  return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> LogN;
+}
+
 inline size_t G1BlockOffsetSharedArray::index_for(const void* p) const {
   char* pc = (char*)p;
   assert(pc >= (char*)_reserved.start() &&
          pc <  (char*)_reserved.end(),
          err_msg("p (" PTR_FORMAT ") not in reserved [" PTR_FORMAT ", " PTR_FORMAT ")",
                  p2i(p), p2i(_reserved.start()), p2i(_reserved.end())));
-  size_t delta = pointer_delta(pc, _reserved.start(), sizeof(char));
-  size_t result = delta >> LogN;
+  size_t result = index_for_raw(p);
   check_index(result, "bad index from address");
   return result;
 }
@@ -62,7 +117,7 @@
 inline HeapWord*
 G1BlockOffsetSharedArray::address_for_index(size_t index) const {
   check_index(index, "index out of range");
-  HeapWord* result = _reserved.start() + (index << LogN_words);
+  HeapWord* result = address_for_index_raw(index);
   assert(result >= _reserved.start() && result < _reserved.end(),
          err_msg("bad address from index result " PTR_FORMAT
                  " _reserved.start() " PTR_FORMAT " _reserved.end() "
@@ -71,6 +126,8 @@
   return result;
 }
 
+#undef check_index
+
 inline size_t
 G1BlockOffsetArray::block_size(const HeapWord* p) const {
   return gsp()->block_size(p);
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -33,31 +33,26 @@
 
 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
 
+void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
+  MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
+  _counts->clear_range(mr);
+}
+
 void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {
   if (has_count_table()) {
-    assert(from_card_num >= 0 && from_card_num < _committed_max_card_num,
-           err_msg("from card num out of range: "SIZE_FORMAT, from_card_num));
     assert(from_card_num < to_card_num,
            err_msg("Wrong order? from: " SIZE_FORMAT ", to: "SIZE_FORMAT,
                    from_card_num, to_card_num));
-    assert(to_card_num <= _committed_max_card_num,
-           err_msg("to card num out of range: "
-                   "to: "SIZE_FORMAT ", "
-                   "max: "SIZE_FORMAT,
-                   to_card_num, _committed_max_card_num));
-
-    to_card_num = MIN2(_committed_max_card_num, to_card_num);
-
     Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));
   }
 }
 
 G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):
-  _g1h(g1h), _card_counts(NULL),
-  _reserved_max_card_num(0), _committed_max_card_num(0),
-  _committed_size(0) {}
+  _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) {
+  _listener.set_cardcounts(this);
+}
 
-void G1CardCounts::initialize() {
+void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) {
   assert(_g1h->max_capacity() > 0, "initialization order");
   assert(_g1h->capacity() == 0, "initialization order");
 
@@ -70,70 +65,9 @@
     _ct_bs = _g1h->g1_barrier_set();
     _ct_bot = _ct_bs->byte_for_const(_g1h->reserved_region().start());
 
-    // Allocate/Reserve the counts table
-    size_t reserved_bytes = _g1h->max_capacity();
-    _reserved_max_card_num = reserved_bytes >> CardTableModRefBS::card_shift;
-
-    size_t reserved_size = _reserved_max_card_num * sizeof(jbyte);
-    ReservedSpace rs(ReservedSpace::allocation_align_size_up(reserved_size));
-    if (!rs.is_reserved()) {
-      warning("Could not reserve enough space for the card counts table");
-      guarantee(!has_reserved_count_table(), "should be NULL");
-      return;
-    }
-
-    MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
-
-    _card_counts_storage.initialize(rs, 0);
-    _card_counts = (jubyte*) _card_counts_storage.low();
-  }
-}
-
-void G1CardCounts::resize(size_t heap_capacity) {
-  // Expand the card counts table to handle a heap with the given capacity.
-
-  if (!has_reserved_count_table()) {
-    // Don't expand if we failed to reserve the card counts table.
-    return;
-  }
-
-  assert(_committed_size ==
-         ReservedSpace::allocation_align_size_up(_committed_size),
-         err_msg("Unaligned? committed_size: " SIZE_FORMAT, _committed_size));
-
-  // Verify that the committed space for the card counts matches our
-  // committed max card num. Note for some allocation alignments, the
-  // amount of space actually committed for the counts table will be able
-  // to span more cards than the number spanned by the maximum heap.
-  size_t prev_committed_size = _committed_size;
-  size_t prev_committed_card_num = committed_to_card_num(prev_committed_size);
-
-  assert(prev_committed_card_num == _committed_max_card_num,
-         err_msg("Card mismatch: "
-                 "prev: " SIZE_FORMAT ", "
-                 "committed: "SIZE_FORMAT", "
-                 "reserved: "SIZE_FORMAT,
-                 prev_committed_card_num, _committed_max_card_num, _reserved_max_card_num));
-
-  size_t new_size = (heap_capacity >> CardTableModRefBS::card_shift) * sizeof(jbyte);
-  size_t new_committed_size = ReservedSpace::allocation_align_size_up(new_size);
-  size_t new_committed_card_num = committed_to_card_num(new_committed_size);
-
-  if (_committed_max_card_num < new_committed_card_num) {
-    // we need to expand the backing store for the card counts
-    size_t expand_size = new_committed_size - prev_committed_size;
-
-    if (!_card_counts_storage.expand_by(expand_size)) {
-      warning("Card counts table backing store commit failure");
-      return;
-    }
-    assert(_card_counts_storage.committed_size() == new_committed_size,
-           "expansion commit failure");
-
-    _committed_size = new_committed_size;
-    _committed_max_card_num = new_committed_card_num;
-
-    clear_range(prev_committed_card_num, _committed_max_card_num);
+    _card_counts = (jubyte*) mapper->reserved().start();
+    _reserved_max_card_num = mapper->reserved().byte_size();
+    mapper->set_mapping_changed_listener(&_listener);
   }
 }
 
@@ -149,12 +83,13 @@
   uint count = 0;
   if (has_count_table()) {
     size_t card_num = ptr_2_card_num(card_ptr);
-    if (card_num < _committed_max_card_num) {
-      count = (uint) _card_counts[card_num];
-      if (count < G1ConcRSHotCardLimit) {
-        _card_counts[card_num] =
-          (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
-      }
+    assert(card_num < _reserved_max_card_num,
+           err_msg("Card "SIZE_FORMAT" outside of card counts table (max size "SIZE_FORMAT")",
+                   card_num, _reserved_max_card_num));
+    count = (uint) _card_counts[card_num];
+    if (count < G1ConcRSHotCardLimit) {
+      _card_counts[card_num] =
+        (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));
     }
   }
   return count;
@@ -165,31 +100,23 @@
 }
 
 void G1CardCounts::clear_region(HeapRegion* hr) {
-  assert(!hr->isHumongous(), "Should have been cleared");
+  MemRegion mr(hr->bottom(), hr->end());
+  clear_range(mr);
+}
+
+void G1CardCounts::clear_range(MemRegion mr) {
   if (has_count_table()) {
-    HeapWord* bottom = hr->bottom();
-
-    // We use the last address in hr as hr could be the
-    // last region in the heap. In which case trying to find
-    // the card for hr->end() will be an OOB access to the
-    // card table.
-    HeapWord* last = hr->end() - 1;
-    assert(_g1h->g1_committed().contains(last),
-           err_msg("last not in committed: "
-                   "last: " PTR_FORMAT ", "
-                   "committed: [" PTR_FORMAT ", " PTR_FORMAT ")",
-                   last,
-                   _g1h->g1_committed().start(),
-                   _g1h->g1_committed().end()));
-
-    const jbyte* from_card_ptr = _ct_bs->byte_for_const(bottom);
-    const jbyte* last_card_ptr = _ct_bs->byte_for_const(last);
+    const jbyte* from_card_ptr = _ct_bs->byte_for_const(mr.start());
+    // We use the last address in the range as the range could represent the
+    // last region in the heap. In which case trying to find the card will be an
+    // OOB access to the card table.
+    const jbyte* last_card_ptr = _ct_bs->byte_for_const(mr.last());
 
 #ifdef ASSERT
     HeapWord* start_addr = _ct_bs->addr_for(from_card_ptr);
-    assert(start_addr == hr->bottom(), "alignment");
+    assert(start_addr == mr.start(), "MemRegion start must be aligned to a card.");
     HeapWord* last_addr = _ct_bs->addr_for(last_card_ptr);
-    assert((last_addr + CardTableModRefBS::card_size_in_words) == hr->end(), "alignment");
+    assert((last_addr + CardTableModRefBS::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card.");
 #endif // ASSERT
 
     // Clear the counts for the (exclusive) card range.
@@ -199,14 +126,22 @@
   }
 }
 
+class G1CardCountsClearClosure : public HeapRegionClosure {
+ private:
+  G1CardCounts* _card_counts;
+ public:
+  G1CardCountsClearClosure(G1CardCounts* card_counts) :
+    HeapRegionClosure(), _card_counts(card_counts) { }
+
+
+  virtual bool doHeapRegion(HeapRegion* r) {
+    _card_counts->clear_region(r);
+    return false;
+  }
+};
+
 void G1CardCounts::clear_all() {
   assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");
-  clear_range((size_t)0, _committed_max_card_num);
+  G1CardCountsClearClosure cl(this);
+  _g1h->heap_region_iterate(&cl);
 }
-
-G1CardCounts::~G1CardCounts() {
-  if (has_reserved_count_table()) {
-    _card_counts_storage.release();
-  }
-}
-
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CardCounts.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -25,14 +25,26 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP
 
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "memory/allocation.hpp"
 #include "runtime/virtualspace.hpp"
 #include "utilities/globalDefinitions.hpp"
 
 class CardTableModRefBS;
+class G1CardCounts;
 class G1CollectedHeap;
+class G1RegionToSpaceMapper;
 class HeapRegion;
 
+class G1CardCountsMappingChangedListener : public G1MappingChangedListener {
+ private:
+  G1CardCounts* _counts;
+ public:
+  void set_cardcounts(G1CardCounts* counts) { _counts = counts; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions);
+};
+
 // Table to track the number of times a card has been refined. Once
 // a card has been refined a certain number of times, it is
 // considered 'hot' and its refinement is delayed by inserting the
@@ -41,6 +53,8 @@
 // is 'drained' during the next evacuation pause.
 
 class G1CardCounts: public CHeapObj<mtGC> {
+  G1CardCountsMappingChangedListener _listener;
+
   G1CollectedHeap* _g1h;
 
   // The table of counts
@@ -49,27 +63,18 @@
   // Max capacity of the reserved space for the counts table
   size_t _reserved_max_card_num;
 
-  // Max capacity of the committed space for the counts table
-  size_t _committed_max_card_num;
-
-  // Size of committed space for the counts table
-  size_t _committed_size;
-
   // CardTable bottom.
   const jbyte* _ct_bot;
 
   // Barrier set
   CardTableModRefBS* _ct_bs;
 
-  // The virtual memory backing the counts table
-  VirtualSpace _card_counts_storage;
-
   // Returns true if the card counts table has been reserved.
   bool has_reserved_count_table() { return _card_counts != NULL; }
 
   // Returns true if the card counts table has been reserved and committed.
   bool has_count_table() {
-    return has_reserved_count_table() && _committed_max_card_num > 0;
+    return has_reserved_count_table();
   }
 
   size_t ptr_2_card_num(const jbyte* card_ptr) {
@@ -79,37 +84,24 @@
                    "_ct_bot: " PTR_FORMAT,
                    p2i(card_ptr), p2i(_ct_bot)));
     size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));
-    assert(card_num >= 0 && card_num < _committed_max_card_num,
+    assert(card_num >= 0 && card_num < _reserved_max_card_num,
            err_msg("card pointer out of range: " PTR_FORMAT, p2i(card_ptr)));
     return card_num;
   }
 
   jbyte* card_num_2_ptr(size_t card_num) {
-    assert(card_num >= 0 && card_num < _committed_max_card_num,
+    assert(card_num >= 0 && card_num < _reserved_max_card_num,
            err_msg("card num out of range: "SIZE_FORMAT, card_num));
     return (jbyte*) (_ct_bot + card_num);
   }
 
-  // Helper routine.
-  // Returns the number of cards that can be counted by the given committed
-  // table size, with a maximum of the number of cards spanned by the max
-  // capacity of the heap.
-  size_t committed_to_card_num(size_t committed_size) {
-    return MIN2(_reserved_max_card_num, committed_size / sizeof(jbyte));
-  }
-
   // Clear the counts table for the given (exclusive) index range.
   void clear_range(size_t from_card_num, size_t to_card_num);
 
  public:
   G1CardCounts(G1CollectedHeap* g1h);
-  ~G1CardCounts();
 
-  void initialize();
-
-  // Resize the committed space for the card counts table in
-  // response to a resize of the committed space for the heap.
-  void resize(size_t heap_capacity);
+  void initialize(G1RegionToSpaceMapper* mapper);
 
   // Increments the refinement count for the given card.
   // Returns the pre-increment count value.
@@ -122,8 +114,10 @@
   // Clears the card counts for the cards spanned by the region
   void clear_region(HeapRegion* hr);
 
+  // Clears the card counts for the cards spanned by the MemRegion
+  void clear_range(MemRegion mr);
+
   // Clear the entire card counts table during GC.
-  // Updates the policy stats with the duration.
   void clear_all();
 };
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -45,12 +45,13 @@
 #include "gc_implementation/g1/g1MarkSweep.hpp"
 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "gc_implementation/g1/g1RemSet.inline.hpp"
 #include "gc_implementation/g1/g1StringDedup.hpp"
 #include "gc_implementation/g1/g1YCTypes.hpp"
 #include "gc_implementation/g1/heapRegion.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
-#include "gc_implementation/g1/heapRegionSeq.inline.hpp"
+#include "gc_implementation/g1/heapRegionSet.inline.hpp"
 #include "gc_implementation/g1/vm_operations_g1.hpp"
 #include "gc_implementation/shared/gcHeapSummary.hpp"
 #include "gc_implementation/shared/gcTimer.hpp"
@@ -381,6 +382,14 @@
   gclog_or_tty->cr();
 }
 
+void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
+  OtherRegionsTable::invalidate(start_idx, num_regions);
+}
+
+void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
+  reset_from_card_cache(start_idx, num_regions);
+}
+
 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 {
   // Claim the right to put the region on the dirty cards region list
@@ -523,9 +532,9 @@
       // again to allocate from it.
       append_secondary_free_list();
 
-      assert(!_free_list.is_empty(), "if the secondary_free_list was not "
+      assert(_hrs.num_free_regions() > 0, "if the secondary_free_list was not "
              "empty we should have moved at least one entry to the free_list");
-      HeapRegion* res = _free_list.remove_region(is_old);
+      HeapRegion* res = _hrs.allocate_free_region(is_old);
       if (G1ConcRegionFreeingVerbose) {
         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
                                "allocated "HR_FORMAT" from secondary_free_list",
@@ -566,7 +575,7 @@
     }
   }
 
-  res = _free_list.remove_region(is_old);
+  res = _hrs.allocate_free_region(is_old);
 
   if (res == NULL) {
     if (G1ConcRegionFreeingVerbose) {
@@ -591,8 +600,8 @@
       // Given that expand() succeeded in expanding the heap, and we
       // always expand the heap by an amount aligned to the heap
       // region size, the free list should in theory not be empty.
-      // In either case remove_region() will check for NULL.
-      res = _free_list.remove_region(is_old);
+      // In either case allocate_free_region() will check for NULL.
+      res = _hrs.allocate_free_region(is_old);
     } else {
       _expand_heap_after_alloc_failure = false;
     }
@@ -600,55 +609,11 @@
   return res;
 }
 
-uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
-                                                        size_t word_size) {
-  assert(isHumongous(word_size), "word_size should be humongous");
-  assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
-
-  uint first = G1_NULL_HRS_INDEX;
-  if (num_regions == 1) {
-    // Only one region to allocate, no need to go through the slower
-    // path. The caller will attempt the expansion if this fails, so
-    // let's not try to expand here too.
-    HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
-    if (hr != NULL) {
-      first = hr->hrs_index();
-    } else {
-      first = G1_NULL_HRS_INDEX;
-    }
-  } else {
-    // We can't allocate humongous regions while cleanupComplete() is
-    // running, since some of the regions we find to be empty might not
-    // yet be added to the free list and it is not straightforward to
-    // know which list they are on so that we can remove them. Note
-    // that we only need to do this if we need to allocate more than
-    // one region to satisfy the current humongous allocation
-    // request. If we are only allocating one region we use the common
-    // region allocation code (see above).
-    wait_while_free_regions_coming();
-    append_secondary_free_list_if_not_empty_with_lock();
-
-    if (free_regions() >= num_regions) {
-      first = _hrs.find_contiguous(num_regions);
-      if (first != G1_NULL_HRS_INDEX) {
-        for (uint i = first; i < first + num_regions; ++i) {
-          HeapRegion* hr = region_at(i);
-          assert(hr->is_empty(), "sanity");
-          assert(is_on_master_free_list(hr), "sanity");
-          hr->set_pending_removal(true);
-        }
-        _free_list.remove_all_pending(num_regions);
-      }
-    }
-  }
-  return first;
-}
-
 HeapWord*
 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
                                                            uint num_regions,
                                                            size_t word_size) {
-  assert(first != G1_NULL_HRS_INDEX, "pre-condition");
+  assert(first != G1_NO_HRS_INDEX, "pre-condition");
   assert(isHumongous(word_size), "word_size should be humongous");
   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 
@@ -786,42 +751,70 @@
 
   verify_region_sets_optional();
 
-  size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
-  uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
-  uint x_num = expansion_regions();
-  uint fs = _hrs.free_suffix();
-  uint first = humongous_obj_allocate_find_first(num_regions, word_size);
-  if (first == G1_NULL_HRS_INDEX) {
-    // The only thing we can do now is attempt expansion.
-    if (fs + x_num >= num_regions) {
-      // If the number of regions we're trying to allocate for this
-      // object is at most the number of regions in the free suffix,
-      // then the call to humongous_obj_allocate_find_first() above
-      // should have succeeded and we wouldn't be here.
-      //
-      // We should only be trying to expand when the free suffix is
-      // not sufficient for the object _and_ we have some expansion
-      // room available.
-      assert(num_regions > fs, "earlier allocation should have succeeded");
-
+  uint first = G1_NO_HRS_INDEX;
+  uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
+
+  if (obj_regions == 1) {
+    // Only one region to allocate, try to use a fast path by directly allocating
+    // from the free lists. Do not try to expand here, we will potentially do that
+    // later.
+    HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
+    if (hr != NULL) {
+      first = hr->hrs_index();
+    }
+  } else {
+    // We can't allocate humongous regions spanning more than one region while
+    // cleanupComplete() is running, since some of the regions we find to be
+    // empty might not yet be added to the free list. It is not straightforward
+    // to know in which list they are on so that we can remove them. We only
+    // need to do this if we need to allocate more than one region to satisfy the
+    // current humongous allocation request. If we are only allocating one region
+    // we use the one-region region allocation code (see above), that already
+    // potentially waits for regions from the secondary free list.
+    wait_while_free_regions_coming();
+    append_secondary_free_list_if_not_empty_with_lock();
+
+    // Policy: Try only empty regions (i.e. already committed first). Maybe we
+    // are lucky enough to find some.
+    first = _hrs.find_contiguous_only_empty(obj_regions);
+    if (first != G1_NO_HRS_INDEX) {
+      _hrs.allocate_free_regions_starting_at(first, obj_regions);
+    }
+  }
+
+  if (first == G1_NO_HRS_INDEX) {
+    // Policy: We could not find enough regions for the humongous object in the
+    // free list. Look through the heap to find a mix of free and uncommitted regions.
+    // If so, try expansion.
+    first = _hrs.find_contiguous_empty_or_unavailable(obj_regions);
+    if (first != G1_NO_HRS_INDEX) {
+      // We found something. Make sure these regions are committed, i.e. expand
+      // the heap. Alternatively we could do a defragmentation GC.
       ergo_verbose1(ErgoHeapSizing,
                     "attempt heap expansion",
                     ergo_format_reason("humongous allocation request failed")
                     ergo_format_byte("allocation request"),
                     word_size * HeapWordSize);
-      if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
-        // Even though the heap was expanded, it might not have
-        // reached the desired size. So, we cannot assume that the
-        // allocation will succeed.
-        first = humongous_obj_allocate_find_first(num_regions, word_size);
+
+      _hrs.expand_at(first, obj_regions);
+      g1_policy()->record_new_heap_size(num_regions());
+
+#ifdef ASSERT
+      for (uint i = first; i < first + obj_regions; ++i) {
+        HeapRegion* hr = region_at(i);
+        assert(hr->is_empty(), "sanity");
+        assert(is_on_master_free_list(hr), "sanity");
       }
+#endif
+      _hrs.allocate_free_regions_starting_at(first, obj_regions);
+    } else {
+      // Policy: Potentially trigger a defragmentation GC.
     }
   }
 
   HeapWord* result = NULL;
-  if (first != G1_NULL_HRS_INDEX) {
-    result =
-      humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
+  if (first != G1_NO_HRS_INDEX) {
+    result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
     assert(result != NULL, "it should always return a valid result");
 
     // A successful humongous object allocation changes the used space
@@ -1384,7 +1377,7 @@
         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
       }
 
-      assert(free_regions() == 0, "we should not have added any free regions");
+      assert(num_free_regions() == 0, "we should not have added any free regions");
       rebuild_region_sets(false /* free_list_only */);
 
       // Enqueue any discovered reference objects that have
@@ -1749,21 +1742,6 @@
   return NULL;
 }
 
-void G1CollectedHeap::update_committed_space(HeapWord* old_end,
-                                             HeapWord* new_end) {
-  assert(old_end != new_end, "don't call this otherwise");
-  assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
-
-  // Update the committed mem region.
-  _g1_committed.set_end(new_end);
-  // Tell the card table about the update.
-  Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
-  // Tell the BOT about the update.
-  _bot_shared->resize(_g1_committed.word_size());
-  // Tell the hot card cache about the update
-  _cg1r->hot_card_cache()->resize_card_counts(capacity());
-}
-
 bool G1CollectedHeap::expand(size_t expand_bytes) {
   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
@@ -1774,55 +1752,22 @@
                 ergo_format_byte("attempted expansion amount"),
                 expand_bytes, aligned_expand_bytes);
 
-  if (_g1_storage.uncommitted_size() == 0) {
+  if (is_maximal_no_gc()) {
     ergo_verbose0(ErgoHeapSizing,
                       "did not expand the heap",
                       ergo_format_reason("heap already fully expanded"));
     return false;
   }
 
-  // First commit the memory.
-  HeapWord* old_end = (HeapWord*) _g1_storage.high();
-  bool successful = _g1_storage.expand_by(aligned_expand_bytes);
-  if (successful) {
-    // Then propagate this update to the necessary data structures.
-    HeapWord* new_end = (HeapWord*) _g1_storage.high();
-    update_committed_space(old_end, new_end);
-
-    FreeRegionList expansion_list("Local Expansion List");
-    MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
-    assert(mr.start() == old_end, "post-condition");
-    // mr might be a smaller region than what was requested if
-    // expand_by() was unable to allocate the HeapRegion instances
-    assert(mr.end() <= new_end, "post-condition");
-
-    size_t actual_expand_bytes = mr.byte_size();
+  uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
+  assert(regions_to_expand > 0, "Must expand by at least one region");
+
+  uint expanded_by = _hrs.expand_by(regions_to_expand);
+
+  if (expanded_by > 0) {
+    size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
-    assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
-           "post-condition");
-    if (actual_expand_bytes < aligned_expand_bytes) {
-      // We could not expand _hrs to the desired size. In this case we
-      // need to shrink the committed space accordingly.
-      assert(mr.end() < new_end, "invariant");
-
-      size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
-      // First uncommit the memory.
-      _g1_storage.shrink_by(diff_bytes);
-      // Then propagate this update to the necessary data structures.
-      update_committed_space(new_end, mr.end());
-    }
-    _free_list.add_as_tail(&expansion_list);
-
-    if (_hr_printer.is_active()) {
-      HeapWord* curr = mr.start();
-      while (curr < mr.end()) {
-        HeapWord* curr_end = curr + HeapRegion::GrainWords;
-        _hr_printer.commit(curr, curr_end);
-        curr = curr_end;
-      }
-      assert(curr == mr.end(), "post-condition");
-    }
-    g1_policy()->record_new_heap_size(n_regions());
+    g1_policy()->record_new_heap_size(num_regions());
   } else {
     ergo_verbose0(ErgoHeapSizing,
                   "did not expand the heap",
@@ -1830,12 +1775,12 @@
     // The expansion of the virtual storage space was unsuccessful.
     // Let's see if it was because we ran out of swap.
     if (G1ExitOnExpansionFailure &&
-        _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
+        _hrs.available() >= regions_to_expand) {
       // We had head room...
       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
     }
   }
-  return successful;
+  return regions_to_expand > 0;
 }
 
 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
@@ -1846,7 +1791,6 @@
   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
 
   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
-  HeapWord* old_end = (HeapWord*) _g1_storage.high();
   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
 
   ergo_verbose3(ErgoHeapSizing,
@@ -1856,22 +1800,7 @@
                 ergo_format_byte("attempted shrinking amount"),
                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
   if (num_regions_removed > 0) {
-    _g1_storage.shrink_by(shrunk_bytes);
-    HeapWord* new_end = (HeapWord*) _g1_storage.high();
-
-    if (_hr_printer.is_active()) {
-      HeapWord* curr = old_end;
-      while (curr > new_end) {
-        HeapWord* curr_end = curr;
-        curr -= HeapRegion::GrainWords;
-        _hr_printer.uncommit(curr, curr_end);
-      }
-    }
-
-    _expansion_regions += num_regions_removed;
-    update_committed_space(old_end, new_end);
-    HeapRegionRemSet::shrink_heap(n_regions());
-    g1_policy()->record_new_heap_size(n_regions());
+    g1_policy()->record_new_heap_size(num_regions());
   } else {
     ergo_verbose0(ErgoHeapSizing,
                   "did not shrink the heap",
@@ -1922,7 +1851,6 @@
   _g1mm(NULL),
   _refine_cte_cl(NULL),
   _full_collection(false),
-  _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
@@ -2036,8 +1964,6 @@
   _reserved.set_start((HeapWord*)heap_rs.base());
   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
 
-  _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
-
   // Create the gen rem set (and barrier set) for the entire reserved region.
   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
   set_barrier_set(rem_set()->bs());
@@ -2051,20 +1977,65 @@
 
   // Carve out the G1 part of the heap.
 
-  ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
-  _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
-                           g1_rs.size()/HeapWordSize);
-
-  _g1_storage.initialize(g1_rs, 0);
-  _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
-  _hrs.initialize((HeapWord*) _g1_reserved.start(),
-                  (HeapWord*) _g1_reserved.end());
-  assert(_hrs.max_length() == _expansion_regions,
-         err_msg("max length: %u expansion regions: %u",
-                 _hrs.max_length(), _expansion_regions));
-
-  // Do later initialization work for concurrent refinement.
-  _cg1r->init();
+  ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
+  G1RegionToSpaceMapper* heap_storage =
+    G1RegionToSpaceMapper::create_mapper(g1_rs,
+                                         UseLargePages ? os::large_page_size() : os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         1,
+                                         mtJavaHeap);
+  heap_storage->set_mapping_changed_listener(&_listener);
+
+  // Reserve space for the block offset table. We do not support automatic uncommit
+  // for the card table at this time. BOT only.
+  ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
+  G1RegionToSpaceMapper* bot_storage =
+    G1RegionToSpaceMapper::create_mapper(bot_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         G1BlockOffsetSharedArray::N_bytes,
+                                         mtGC);
+
+  ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
+  G1RegionToSpaceMapper* cardtable_storage =
+    G1RegionToSpaceMapper::create_mapper(cardtable_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         G1BlockOffsetSharedArray::N_bytes,
+                                         mtGC);
+
+  // Reserve space for the card counts table.
+  ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
+  G1RegionToSpaceMapper* card_counts_storage =
+    G1RegionToSpaceMapper::create_mapper(card_counts_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         G1BlockOffsetSharedArray::N_bytes,
+                                         mtGC);
+
+  // Reserve space for prev and next bitmap.
+  size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
+
+  ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
+  G1RegionToSpaceMapper* prev_bitmap_storage =
+    G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         CMBitMap::mark_distance(),
+                                         mtGC);
+
+  ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
+  G1RegionToSpaceMapper* next_bitmap_storage =
+    G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         CMBitMap::mark_distance(),
+                                         mtGC);
+
+  _hrs.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
+  g1_barrier_set()->initialize(cardtable_storage);
+   // Do later initialization work for concurrent refinement.
+  _cg1r->init(card_counts_storage);
 
   // 6843694 - ensure that the maximum region index can fit
   // in the remembered set structures.
@@ -2078,17 +2049,16 @@
 
   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
 
-  _bot_shared = new G1BlockOffsetSharedArray(_reserved,
-                                             heap_word_size(init_byte_size));
+  _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
 
   _g1h = this;
 
-  _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
-  _humongous_is_live.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
+  _in_cset_fast_test.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
+  _humongous_is_live.initialize(_hrs.reserved().start(), _hrs.reserved().end(), HeapRegion::GrainBytes);
 
   // Create the ConcurrentMark data structure and thread.
   // (Must do this late, so that "max_regions" is defined.)
-  _cm = new ConcurrentMark(this, heap_rs);
+  _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
   if (_cm == NULL || !_cm->completed_initialization()) {
     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
     return JNI_ENOMEM;
@@ -2143,12 +2113,10 @@
   // counts and that mechanism.
   SpecializationStats::clear();
 
-  // Here we allocate the dummy full region that is required by the
-  // G1AllocRegion class. If we don't pass an address in the reserved
-  // space here, lots of asserts fire.
-
-  HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
-                                             _g1_reserved.start());
+  // Here we allocate the dummy HeapRegion that is required by the
+  // G1AllocRegion class.
+  HeapRegion* dummy_region = _hrs.get_dummy_region();
+
   // We'll re-use the same region whether the alloc region will
   // require BOT updates or not and, if it doesn't, then a non-young
   // region will complain that it cannot support allocations without
@@ -2264,7 +2232,7 @@
 }
 
 size_t G1CollectedHeap::capacity() const {
-  return _g1_committed.byte_size();
+  return _hrs.length() * HeapRegion::GrainBytes;
 }
 
 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
@@ -2569,8 +2537,8 @@
 }
 
 bool G1CollectedHeap::is_in(const void* p) const {
-  if (_g1_committed.contains(p)) {
-    // Given that we know that p is in the committed space,
+  if (_hrs.reserved().contains(p)) {
+    // Given that we know that p is in the reserved space,
     // heap_region_containing_raw() should successfully
     // return the containing region.
     HeapRegion* hr = heap_region_containing_raw(p);
@@ -2580,6 +2548,18 @@
   }
 }
 
+#ifdef ASSERT
+bool G1CollectedHeap::is_in_exact(const void* p) const {
+  bool contains = reserved_region().contains(p);
+  bool available = _hrs.is_available(addr_to_region((HeapWord*)p));
+  if (contains && available) {
+    return true;
+  } else {
+    return false;
+  }
+}
+#endif
+
 // Iteration functions.
 
 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
@@ -2644,83 +2624,9 @@
 void
 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
                                                  uint worker_id,
-                                                 uint no_of_par_workers,
-                                                 jint claim_value) {
-  const uint regions = n_regions();
-  const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
-                             no_of_par_workers :
-                             1);
-  assert(UseDynamicNumberOfGCThreads ||
-         no_of_par_workers == workers()->total_workers(),
-         "Non dynamic should use fixed number of workers");
-  // try to spread out the starting points of the workers
-  const HeapRegion* start_hr =
-                        start_region_for_worker(worker_id, no_of_par_workers);
-  const uint start_index = start_hr->hrs_index();
-
-  // each worker will actually look at all regions
-  for (uint count = 0; count < regions; ++count) {
-    const uint index = (start_index + count) % regions;
-    assert(0 <= index && index < regions, "sanity");
-    HeapRegion* r = region_at(index);
-    // we'll ignore "continues humongous" regions (we'll process them
-    // when we come across their corresponding "start humongous"
-    // region) and regions already claimed
-    if (r->claim_value() == claim_value || r->continuesHumongous()) {
-      continue;
-    }
-    // OK, try to claim it
-    if (r->claimHeapRegion(claim_value)) {
-      // success!
-      assert(!r->continuesHumongous(), "sanity");
-      if (r->startsHumongous()) {
-        // If the region is "starts humongous" we'll iterate over its
-        // "continues humongous" first; in fact we'll do them
-        // first. The order is important. In on case, calling the
-        // closure on the "starts humongous" region might de-allocate
-        // and clear all its "continues humongous" regions and, as a
-        // result, we might end up processing them twice. So, we'll do
-        // them first (notice: most closures will ignore them anyway) and
-        // then we'll do the "starts humongous" region.
-        for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
-          HeapRegion* chr = region_at(ch_index);
-
-          // if the region has already been claimed or it's not
-          // "continues humongous" we're done
-          if (chr->claim_value() == claim_value ||
-              !chr->continuesHumongous()) {
-            break;
-          }
-
-          // No one should have claimed it directly. We can given
-          // that we claimed its "starts humongous" region.
-          assert(chr->claim_value() != claim_value, "sanity");
-          assert(chr->humongous_start_region() == r, "sanity");
-
-          if (chr->claimHeapRegion(claim_value)) {
-            // we should always be able to claim it; no one else should
-            // be trying to claim this region
-
-            bool res2 = cl->doHeapRegion(chr);
-            assert(!res2, "Should not abort");
-
-            // Right now, this holds (i.e., no closure that actually
-            // does something with "continues humongous" regions
-            // clears them). We might have to weaken it in the future,
-            // but let's leave these two asserts here for extra safety.
-            assert(chr->continuesHumongous(), "should still be the case");
-            assert(chr->humongous_start_region() == r, "sanity");
-          } else {
-            guarantee(false, "we should not reach here");
-          }
-        }
-      }
-
-      assert(!r->continuesHumongous(), "sanity");
-      bool res = cl->doHeapRegion(r);
-      assert(!res, "Should not abort");
-    }
-  }
+                                                 uint num_workers,
+                                                 jint claim_value) const {
+  _hrs.par_iterate(cl, worker_id, num_workers, claim_value);
 }
 
 class ResetClaimValuesClosure: public HeapRegionClosure {
@@ -2898,17 +2804,6 @@
   return result;
 }
 
-HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
-                                                     uint no_of_par_workers) {
-  uint worker_num =
-           G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
-  assert(UseDynamicNumberOfGCThreads ||
-         no_of_par_workers == workers()->total_workers(),
-         "Non dynamic should use fixed number of workers");
-  const uint start_index = n_regions() * worker_i / worker_num;
-  return region_at(start_index);
-}
-
 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
   HeapRegion* r = g1_policy()->collection_set();
   while (r != NULL) {
@@ -2951,15 +2846,11 @@
 }
 
 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
-  // We're not using an iterator given that it will wrap around when
-  // it reaches the last region and this is not what we want here.
-  for (uint index = from->hrs_index() + 1; index < n_regions(); index++) {
-    HeapRegion* hr = region_at(index);
-    if (!hr->isHumongous()) {
-      return hr;
-    }
-  }
-  return NULL;
+  HeapRegion* result = _hrs.next_region_in_heap(from);
+  while (result != NULL && result->isHumongous()) {
+    result = _hrs.next_region_in_heap(result);
+  }
+  return result;
 }
 
 Space* G1CollectedHeap::space_containing(const void* addr) const {
@@ -3017,7 +2908,7 @@
 }
 
 size_t G1CollectedHeap::max_capacity() const {
-  return _g1_reserved.byte_size();
+  return _hrs.reserved().byte_size();
 }
 
 jlong G1CollectedHeap::millis_since_last_gc() {
@@ -3546,9 +3437,9 @@
   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
             capacity()/K, used_unlocked()/K);
   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
-            _g1_storage.low_boundary(),
-            _g1_storage.high(),
-            _g1_storage.high_boundary());
+            _hrs.reserved().start(),
+            _hrs.reserved().start() + _hrs.length() + HeapRegion::GrainWords,
+            _hrs.reserved().end());
   st->cr();
   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
   uint young_regions = _young_list->length();
@@ -4239,10 +4130,7 @@
             // No need for an ergo verbose message here,
             // expansion_amount() does this when it returns a value > 0.
             if (!expand(expand_bytes)) {
-              // We failed to expand the heap so let's verify that
-              // committed/uncommitted amount match the backing store
-              assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
-              assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
+              // We failed to expand the heap. Cannot do anything about it.
             }
           }
         }
@@ -4302,10 +4190,6 @@
       // RETIRE events are generated before the end GC event.
       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
 
-      if (mark_in_progress()) {
-        concurrent_mark()->update_g1_committed();
-      }
-
 #ifdef TRACESPINNING
       ParallelTaskTerminator::print_termination_counts();
 #endif
@@ -6140,6 +6024,7 @@
                                   bool locked) {
   assert(!hr->isHumongous(), "this is only for non-humongous regions");
   assert(!hr->is_empty(), "the region should not be empty");
+  assert(_hrs.is_available(hr->hrs_index()), "region should be committed");
   assert(free_list != NULL, "pre-condition");
 
   if (G1VerifyBitmaps) {
@@ -6194,7 +6079,7 @@
   assert(list != NULL, "list can't be null");
   if (!list->is_empty()) {
     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
-    _free_list.add_ordered(list);
+    _hrs.insert_list_into_free_list(list);
   }
 }
 
@@ -6802,22 +6687,22 @@
     // this is that during a full GC string deduplication needs to know if
     // a collected region was young or old when the full GC was initiated.
   }
-  _free_list.remove_all();
+  _hrs.remove_all_free_regions();
 }
 
 class RebuildRegionSetsClosure : public HeapRegionClosure {
 private:
   bool            _free_list_only;
   HeapRegionSet*   _old_set;
-  FreeRegionList* _free_list;
+  HeapRegionSeq*   _hrs;
   size_t          _total_used;
 
 public:
   RebuildRegionSetsClosure(bool free_list_only,
-                           HeapRegionSet* old_set, FreeRegionList* free_list) :
+                           HeapRegionSet* old_set, HeapRegionSeq* hrs) :
     _free_list_only(free_list_only),
-    _old_set(old_set), _free_list(free_list), _total_used(0) {
-    assert(_free_list->is_empty(), "pre-condition");
+    _old_set(old_set), _hrs(hrs), _total_used(0) {
+    assert(_hrs->num_free_regions() == 0, "pre-condition");
     if (!free_list_only) {
       assert(_old_set->is_empty(), "pre-condition");
     }
@@ -6830,7 +6715,7 @@
 
     if (r->is_empty()) {
       // Add free regions to the free list
-      _free_list->add_as_tail(r);
+      _hrs->insert_into_free_list(r);
     } else if (!_free_list_only) {
       assert(!r->is_young(), "we should not come across young regions");
 
@@ -6858,7 +6743,7 @@
     _young_list->empty_list();
   }
 
-  RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
+  RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrs);
   heap_region_iterate(&cl);
 
   if (!free_list_only) {
@@ -7013,13 +6898,42 @@
   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
                                GCAllocForTenured);
 }
+
+HeapRegion* OldGCAllocRegion::release() {
+  HeapRegion* cur = get();
+  if (cur != NULL) {
+    // Determine how far we are from the next card boundary. If it is smaller than
+    // the minimum object size we can allocate into, expand into the next card.
+    HeapWord* top = cur->top();
+    HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes);
+
+    size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
+
+    if (to_allocate_words != 0) {
+      // We are not at a card boundary. Fill up, possibly into the next, taking the
+      // end of the region and the minimum object size into account.
+      to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
+                               MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
+
+      // Skip allocation if there is not enough space to allocate even the smallest
+      // possible object. In this case this region will not be retained, so the
+      // original problem cannot occur.
+      if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
+        HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
+        CollectedHeap::fill_with_object(dummy, to_allocate_words);
+      }
+    }
+  }
+  return G1AllocRegion::release();
+}
+
 // Heap region set verification
 
 class VerifyRegionListsClosure : public HeapRegionClosure {
 private:
   HeapRegionSet*   _old_set;
   HeapRegionSet*   _humongous_set;
-  FreeRegionList*  _free_list;
+  HeapRegionSeq*   _hrs;
 
 public:
   HeapRegionSetCount _old_count;
@@ -7028,8 +6942,8 @@
 
   VerifyRegionListsClosure(HeapRegionSet* old_set,
                            HeapRegionSet* humongous_set,
-                           FreeRegionList* free_list) :
-    _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
+                           HeapRegionSeq* hrs) :
+    _old_set(old_set), _humongous_set(humongous_set), _hrs(hrs),
     _old_count(), _humongous_count(), _free_count(){ }
 
   bool doHeapRegion(HeapRegion* hr) {
@@ -7043,7 +6957,7 @@
       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
       _humongous_count.increment(1u, hr->capacity());
     } else if (hr->is_empty()) {
-      assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
+      assert(_hrs->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
       _free_count.increment(1u, hr->capacity());
     } else {
       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
@@ -7052,7 +6966,7 @@
     return false;
   }
 
-  void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
+  void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionSeq* free_list) {
     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
         old_set->total_capacity_bytes(), _old_count.capacity()));
@@ -7061,26 +6975,17 @@
     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
 
-    guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
+    guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
         free_list->total_capacity_bytes(), _free_count.capacity()));
   }
 };
 
-HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
-                                             HeapWord* bottom) {
-  HeapWord* end = bottom + HeapRegion::GrainWords;
-  MemRegion mr(bottom, end);
-  assert(_g1_reserved.contains(mr), "invariant");
-  // This might return NULL if the allocation fails
-  return new HeapRegion(hrs_index, _bot_shared, mr);
-}
-
 void G1CollectedHeap::verify_region_sets() {
   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 
   // First, check the explicit lists.
-  _free_list.verify_list();
+  _hrs.verify();
   {
     // Given that a concurrent operation might be adding regions to
     // the secondary free list we have to take the lock before
@@ -7111,9 +7016,9 @@
   // Finally, make sure that the region accounting in the lists is
   // consistent with what we see in the heap.
 
-  VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
+  VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrs);
   heap_region_iterate(&cl);
-  cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
+  cl.verify_counts(&_old_set, &_humongous_set, &_hrs);
 }
 
 // Optimized nmethod scanning
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -183,6 +183,13 @@
 public:
   OldGCAllocRegion()
   : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
+
+  // This specialization of release() makes sure that the last card that has been
+  // allocated into has been completely filled by a dummy object.
+  // This avoids races when remembered set scanning wants to update the BOT of the
+  // last card in the retained old gc alloc region, and allocation threads
+  // allocating into that card at the same time.
+  virtual HeapRegion* release();
 };
 
 // The G1 STW is alive closure.
@@ -199,6 +206,13 @@
 
 class RefineCardTableEntryClosure;
 
+class G1RegionMappingChangedListener : public G1MappingChangedListener {
+ private:
+  void reset_from_card_cache(uint start_idx, size_t num_regions);
+ public:
+  virtual void on_commit(uint start_idx, size_t num_regions);
+};
+
 class G1CollectedHeap : public SharedHeap {
   friend class VM_CollectForMetadataAllocation;
   friend class VM_G1CollectForAllocation;
@@ -237,19 +251,9 @@
 
   static size_t _humongous_object_threshold_in_words;
 
-  // Storage for the G1 heap.
-  VirtualSpace _g1_storage;
-  MemRegion    _g1_reserved;
-
-  // The part of _g1_storage that is currently committed.
-  MemRegion _g1_committed;
-
-  // The master free list. It will satisfy all new region allocations.
-  FreeRegionList _free_list;
-
   // The secondary free list which contains regions that have been
-  // freed up during the cleanup process. This will be appended to the
-  // master free list when appropriate.
+  // freed up during the cleanup process. This will be appended to
+  // the master free list when appropriate.
   FreeRegionList _secondary_free_list;
 
   // It keeps track of the old regions.
@@ -283,6 +287,9 @@
   // after heap shrinking (free_list_only == true).
   void rebuild_region_sets(bool free_list_only);
 
+  // Callback for region mapping changed events.
+  G1RegionMappingChangedListener _listener;
+
   // The sequence of all heap regions in the heap.
   HeapRegionSeq _hrs;
 
@@ -513,14 +520,6 @@
   // humongous object, set is_old to true. If not, to false.
   HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
 
-  // Attempt to satisfy a humongous allocation request of the given
-  // size by finding a contiguous set of free regions of num_regions
-  // length and remove them from the master free list. Return the
-  // index of the first region or G1_NULL_HRS_INDEX if the search
-  // was unsuccessful.
-  uint humongous_obj_allocate_find_first(uint num_regions,
-                                         size_t word_size);
-
   // Initialize a contiguous set of free regions of length num_regions
   // and starting at index first so that they appear as a single
   // humongous region.
@@ -862,11 +861,6 @@
                         CodeBlobClosure* scan_strong_code,
                         uint worker_i);
 
-  // Notifies all the necessary spaces that the committed space has
-  // been updated (either expanded or shrunk). It should be called
-  // after _g1_storage is updated.
-  void update_committed_space(HeapWord* old_end, HeapWord* new_end);
-
   // The concurrent marker (and the thread it runs in.)
   ConcurrentMark* _cm;
   ConcurrentMarkThread* _cmThread;
@@ -1177,27 +1171,20 @@
   // But G1CollectedHeap doesn't yet support this.
 
   virtual bool is_maximal_no_gc() const {
-    return _g1_storage.uncommitted_size() == 0;
+    return _hrs.available() == 0;
   }
 
-  // The total number of regions in the heap.
-  uint n_regions() const { return _hrs.length(); }
+  // The current number of regions in the heap.
+  uint num_regions() const { return _hrs.length(); }
 
   // The max number of regions in the heap.
   uint max_regions() const { return _hrs.max_length(); }
 
   // The number of regions that are completely free.
-  uint free_regions() const { return _free_list.length(); }
+  uint num_free_regions() const { return _hrs.num_free_regions(); }
 
   // The number of regions that are not completely free.
-  uint used_regions() const { return n_regions() - free_regions(); }
-
-  // The number of regions available for "regular" expansion.
-  uint expansion_regions() const { return _expansion_regions; }
-
-  // Factory method for HeapRegion instances. It will return NULL if
-  // the allocation fails.
-  HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom);
+  uint num_used_regions() const { return num_regions() - num_free_regions(); }
 
   void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
   void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN;
@@ -1246,7 +1233,7 @@
 
 #ifdef ASSERT
   bool is_on_master_free_list(HeapRegion* hr) {
-    return hr->containing_set() == &_free_list;
+    return _hrs.is_free(hr);
   }
 #endif // ASSERT
 
@@ -1258,7 +1245,7 @@
   }
 
   void append_secondary_free_list() {
-    _free_list.add_ordered(&_secondary_free_list);
+    _hrs.insert_list_into_free_list(&_secondary_free_list);
   }
 
   void append_secondary_free_list_if_not_empty_with_lock() {
@@ -1304,6 +1291,11 @@
 
   // Returns "TRUE" iff "p" points into the committed areas of the heap.
   virtual bool is_in(const void* p) const;
+#ifdef ASSERT
+  // Returns whether p is in one of the available areas of the heap. Slow but
+  // extensive version.
+  bool is_in_exact(const void* p) const;
+#endif
 
   // Return "TRUE" iff the given object address is within the collection
   // set. Slow implementation.
@@ -1364,25 +1356,19 @@
   // Return "TRUE" iff the given object address is in the reserved
   // region of g1.
   bool is_in_g1_reserved(const void* p) const {
-    return _g1_reserved.contains(p);
+    return _hrs.reserved().contains(p);
   }
 
   // Returns a MemRegion that corresponds to the space that has been
   // reserved for the heap
-  MemRegion g1_reserved() {
-    return _g1_reserved;
-  }
-
-  // Returns a MemRegion that corresponds to the space that has been
-  // committed in the heap
-  MemRegion g1_committed() {
-    return _g1_committed;
+  MemRegion g1_reserved() const {
+    return _hrs.reserved();
   }
 
   virtual bool is_in_closed_subset(const void* p) const;
 
-  G1SATBCardTableModRefBS* g1_barrier_set() {
-    return (G1SATBCardTableModRefBS*) barrier_set();
+  G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
+    return (G1SATBCardTableLoggingModRefBS*) barrier_set();
   }
 
   // This resets the card table to all zeros.  It is used after
@@ -1416,6 +1402,8 @@
   // within the heap.
   inline uint addr_to_region(HeapWord* addr) const;
 
+  inline HeapWord* bottom_addr_for_region(uint index) const;
+
   // Divide the heap region sequence into "chunks" of some size (the number
   // of regions divided by the number of parallel threads times some
   // overpartition factor, currently 4).  Assumes that this will be called
@@ -1429,10 +1417,10 @@
   // setting the claim value of the second and subsequent regions of the
   // chunk.)  For now requires that "doHeapRegion" always returns "false",
   // i.e., that a closure never attempt to abort a traversal.
-  void heap_region_par_iterate_chunked(HeapRegionClosure* blk,
-                                       uint worker,
-                                       uint no_of_par_workers,
-                                       jint claim_value);
+  void heap_region_par_iterate_chunked(HeapRegionClosure* cl,
+                                       uint worker_id,
+                                       uint num_workers,
+                                       jint claim_value) const;
 
   // It resets all the region claim values to the default.
   void reset_heap_region_claim_values();
@@ -1457,11 +1445,6 @@
   // starting region for iterating over the current collection set.
   HeapRegion* start_cset_region_for_worker(uint worker_i);
 
-  // This is a convenience method that is used by the
-  // HeapRegionIterator classes to calculate the starting region for
-  // each worker so that they do not all start from the same region.
-  HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers);
-
   // Iterate over the regions (if any) in the current collection set.
   void collection_set_iterate(HeapRegionClosure* blk);
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.inline.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -47,19 +47,21 @@
   return (uint)(pointer_delta(addr, _reserved.start(), sizeof(uint8_t)) >> HeapRegion::LogOfHRGrainBytes);
 }
 
+inline HeapWord* G1CollectedHeap::bottom_addr_for_region(uint index) const {
+  return _hrs.reserved().start() + index * HeapRegion::GrainWords;
+}
+
 template <class T>
-inline HeapRegion*
-G1CollectedHeap::heap_region_containing_raw(const T addr) const {
+inline HeapRegion* G1CollectedHeap::heap_region_containing_raw(const T addr) const {
   assert(addr != NULL, "invariant");
-  assert(_g1_reserved.contains((const void*) addr),
+  assert(is_in_g1_reserved((const void*) addr),
       err_msg("Address "PTR_FORMAT" is outside of the heap ranging from ["PTR_FORMAT" to "PTR_FORMAT")",
-          p2i((void*)addr), p2i(_g1_reserved.start()), p2i(_g1_reserved.end())));
+          p2i((void*)addr), p2i(g1_reserved().start()), p2i(g1_reserved().end())));
   return _hrs.addr_to_region((HeapWord*) addr);
 }
 
 template <class T>
-inline HeapRegion*
-G1CollectedHeap::heap_region_containing(const T addr) const {
+inline HeapRegion* G1CollectedHeap::heap_region_containing(const T addr) const {
   HeapRegion* hr = heap_region_containing_raw(addr);
   if (hr->continuesHumongous()) {
     return hr->humongous_start_region();
@@ -89,10 +91,9 @@
   return r != NULL && r->in_collection_set();
 }
 
-inline HeapWord*
-G1CollectedHeap::attempt_allocation(size_t word_size,
-                                    unsigned int* gc_count_before_ret,
-                                    int* gclocker_retry_count_ret) {
+inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
+                                                     unsigned int* gc_count_before_ret,
+                                                     int* gclocker_retry_count_ret) {
   assert_heap_not_locked_and_not_at_safepoint();
   assert(!isHumongous(word_size), "attempt_allocation() should not "
          "be called for humongous allocation requests");
@@ -252,8 +253,7 @@
   }
 }
 
-inline bool
-G1CollectedHeap::evacuation_should_fail() {
+inline bool G1CollectedHeap::evacuation_should_fail() {
   if (!G1EvacuationFailureALot || !_evacuation_failure_alot_for_current_gc) {
     return false;
   }
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -456,7 +456,7 @@
   } else {
     _young_list_fixed_length = _young_gen_sizer->min_desired_young_length();
   }
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   update_young_list_target_length();
 
   // We may immediately start allocating regions and placing them on the
@@ -829,7 +829,7 @@
 
   record_survivor_regions(0, NULL, NULL);
 
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   // Reset survivors SurvRateGroup.
   _survivor_surv_rate_group->reset();
   update_young_list_target_length();
@@ -1181,7 +1181,7 @@
 
   _in_marking_window = new_in_marking_window;
   _in_marking_window_im = new_in_marking_window_im;
-  _free_regions_at_end_of_collection = _g1->free_regions();
+  _free_regions_at_end_of_collection = _g1->num_free_regions();
   update_young_list_target_length();
 
   // Note that _mmu_tracker->max_gc_time() returns the time in seconds.
@@ -1203,7 +1203,7 @@
   _survivor_used_bytes_before_gc = young_list->survivor_used_bytes();
   _heap_capacity_bytes_before_gc = _g1->capacity();
   _heap_used_bytes_before_gc = _g1->used();
-  _cur_collection_pause_used_regions_at_start = _g1->used_regions();
+  _cur_collection_pause_used_regions_at_start = _g1->num_used_regions();
 
   _eden_capacity_bytes_before_gc =
          (_young_list_target_length * HeapRegion::GrainBytes) - _survivor_used_bytes_before_gc;
@@ -1618,7 +1618,7 @@
 G1CollectorPolicy::record_concurrent_mark_cleanup_end(int no_of_gc_threads) {
   _collectionSetChooser->clear();
 
-  uint region_num = _g1->n_regions();
+  uint region_num = _g1->num_regions();
   if (G1CollectedHeap::use_parallel_gc_threads()) {
     const uint OverpartitionFactor = 4;
     uint WorkUnit;
@@ -1639,7 +1639,7 @@
         MAX2(region_num / (uint) (ParallelGCThreads * OverpartitionFactor),
              MinWorkUnit);
     }
-    _collectionSetChooser->prepare_for_par_region_addition(_g1->n_regions(),
+    _collectionSetChooser->prepare_for_par_region_addition(_g1->num_regions(),
                                                            WorkUnit);
     ParKnownGarbageTask parKnownGarbageTask(_collectionSetChooser,
                                             (int) WorkUnit);
@@ -1936,7 +1936,7 @@
   // of them are available.
 
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  const size_t region_num = g1h->n_regions();
+  const size_t region_num = g1h->num_regions();
   const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
   size_t result = region_num * perc / 100;
   // emulate ceiling
--- a/hotspot/src/share/vm/gc_implementation/g1/g1HotCardCache.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1HotCardCache.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -33,7 +33,7 @@
 G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):
   _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}
 
-void G1HotCardCache::initialize() {
+void G1HotCardCache::initialize(G1RegionToSpaceMapper* card_counts_storage) {
   if (default_use_cache()) {
     _use_cache = true;
 
@@ -49,7 +49,7 @@
     _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / (int)n_workers);
     _hot_cache_par_claimed_idx = 0;
 
-    _card_counts.initialize();
+    _card_counts.initialize(card_counts_storage);
   }
 }
 
@@ -135,11 +135,8 @@
   // above, are discarded prior to re-enabling the cache near the end of the GC.
 }
 
-void G1HotCardCache::resize_card_counts(size_t heap_capacity) {
-  _card_counts.resize(heap_capacity);
-}
-
 void G1HotCardCache::reset_card_counts(HeapRegion* hr) {
+  assert(!hr->isHumongous(), "Should have been cleared");
   _card_counts.clear_region(hr);
 }
 
--- a/hotspot/src/share/vm/gc_implementation/g1/g1HotCardCache.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1HotCardCache.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -78,7 +78,7 @@
   G1HotCardCache(G1CollectedHeap* g1h);
   ~G1HotCardCache();
 
-  void initialize();
+  void initialize(G1RegionToSpaceMapper* card_counts_storage);
 
   bool use_cache() { return _use_cache; }
 
@@ -115,9 +115,6 @@
 
   bool hot_cache_is_empty() { return _n_hot == 0; }
 
-  // Resizes the card counts table to match the given capacity
-  void resize_card_counts(size_t heap_capacity);
-
   // Zeros the values in the card counts table for entire committed heap
   void reset_card_counts();
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/g1/g1PageBasedVirtualSpace.hpp"
+#include "oops/markOop.hpp"
+#include "oops/oop.inline.hpp"
+#include "services/memTracker.hpp"
+#ifdef TARGET_OS_FAMILY_linux
+# include "os_linux.inline.hpp"
+#endif
+#ifdef TARGET_OS_FAMILY_solaris
+# include "os_solaris.inline.hpp"
+#endif
+#ifdef TARGET_OS_FAMILY_windows
+# include "os_windows.inline.hpp"
+#endif
+#ifdef TARGET_OS_FAMILY_aix
+# include "os_aix.inline.hpp"
+#endif
+#ifdef TARGET_OS_FAMILY_bsd
+# include "os_bsd.inline.hpp"
+#endif
+#include "utilities/bitMap.inline.hpp"
+
+G1PageBasedVirtualSpace::G1PageBasedVirtualSpace() : _low_boundary(NULL),
+  _high_boundary(NULL), _committed(), _page_size(0), _special(false), _executable(false) {
+}
+
+bool G1PageBasedVirtualSpace::initialize_with_granularity(ReservedSpace rs, size_t page_size) {
+  if (!rs.is_reserved()) {
+    return false;  // Allocation failed.
+  }
+  assert(_low_boundary == NULL, "VirtualSpace already initialized");
+  assert(page_size > 0, "Granularity must be non-zero.");
+
+  _low_boundary  = rs.base();
+  _high_boundary = _low_boundary + rs.size();
+
+  _special = rs.special();
+  _executable = rs.executable();
+
+  _page_size = page_size;
+
+  assert(_committed.size() == 0, "virtual space initialized more than once");
+  uintx size_in_bits = rs.size() / page_size;
+  _committed.resize(size_in_bits, /* in_resource_area */ false);
+
+  if (_special) {
+    _committed.set_range(0, size_in_bits);
+  }
+
+  return true;
+}
+
+
+G1PageBasedVirtualSpace::~G1PageBasedVirtualSpace() {
+  release();
+}
+
+void G1PageBasedVirtualSpace::release() {
+  // This does not release memory it never reserved.
+  // Caller must release via rs.release();
+  _low_boundary           = NULL;
+  _high_boundary          = NULL;
+  _special                = false;
+  _executable             = false;
+  _page_size              = 0;
+  _committed.resize(0, false);
+}
+
+size_t G1PageBasedVirtualSpace::committed_size() const {
+  return _committed.count_one_bits() * _page_size;
+}
+
+size_t G1PageBasedVirtualSpace::reserved_size() const {
+  return pointer_delta(_high_boundary, _low_boundary, sizeof(char));
+}
+
+size_t G1PageBasedVirtualSpace::uncommitted_size()  const {
+  return reserved_size() - committed_size();
+}
+
+uintptr_t G1PageBasedVirtualSpace::addr_to_page_index(char* addr) const {
+  return (addr - _low_boundary) / _page_size;
+}
+
+bool G1PageBasedVirtualSpace::is_area_committed(uintptr_t start, size_t size_in_pages) const {
+  uintptr_t end = start + size_in_pages;
+  return _committed.get_next_zero_offset(start, end) >= end;
+}
+
+bool G1PageBasedVirtualSpace::is_area_uncommitted(uintptr_t start, size_t size_in_pages) const {
+  uintptr_t end = start + size_in_pages;
+  return _committed.get_next_one_offset(start, end) >= end;
+}
+
+char* G1PageBasedVirtualSpace::page_start(uintptr_t index) {
+  return _low_boundary + index * _page_size;
+}
+
+size_t G1PageBasedVirtualSpace::byte_size_for_pages(size_t num) {
+  return num * _page_size;
+}
+
+MemRegion G1PageBasedVirtualSpace::commit(uintptr_t start, size_t size_in_pages) {
+  // We need to make sure to commit all pages covered by the given area.
+  guarantee(is_area_uncommitted(start, size_in_pages), "Specified area is not uncommitted");
+
+  if (!_special) {
+    os::commit_memory_or_exit(page_start(start), byte_size_for_pages(size_in_pages), _executable,
+                              err_msg("Failed to commit pages from "SIZE_FORMAT" of length "SIZE_FORMAT, start, size_in_pages));
+  }
+  _committed.set_range(start, start + size_in_pages);
+
+  MemRegion result((HeapWord*)page_start(start), byte_size_for_pages(size_in_pages) / HeapWordSize);
+  return result;
+}
+
+MemRegion G1PageBasedVirtualSpace::uncommit(uintptr_t start, size_t size_in_pages) {
+  guarantee(is_area_committed(start, size_in_pages), "checking");
+
+  if (!_special) {
+    os::uncommit_memory(page_start(start), byte_size_for_pages(size_in_pages));
+  }
+
+  _committed.clear_range(start, start + size_in_pages);
+
+  MemRegion result((HeapWord*)page_start(start), byte_size_for_pages(size_in_pages) / HeapWordSize);
+  return result;
+}
+
+bool G1PageBasedVirtualSpace::contains(const void* p) const {
+  return _low_boundary <= (const char*) p && (const char*) p < _high_boundary;
+}
+
+#ifndef PRODUCT
+void G1PageBasedVirtualSpace::print_on(outputStream* out) {
+  out->print   ("Virtual space:");
+  if (special()) out->print(" (pinned in memory)");
+  out->cr();
+  out->print_cr(" - committed: " SIZE_FORMAT, committed_size());
+  out->print_cr(" - reserved:  " SIZE_FORMAT, reserved_size());
+  out->print_cr(" - [low_b, high_b]: [" INTPTR_FORMAT ", " INTPTR_FORMAT "]",  p2i(_low_boundary), p2i(_high_boundary));
+}
+
+void G1PageBasedVirtualSpace::print() {
+  print_on(tty);
+}
+#endif
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
+
+#include "memory/allocation.hpp"
+#include "memory/memRegion.hpp"
+#include "runtime/virtualspace.hpp"
+#include "utilities/bitMap.hpp"
+
+// Virtual space management helper for a virtual space with an OS page allocation
+// granularity.
+// (De-)Allocation requests are always OS page aligned by passing a page index
+// and multiples of pages.
+// The implementation gives an error when trying to commit or uncommit pages that
+// have already been committed or uncommitted.
+class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
+  friend class VMStructs;
+ private:
+  // Reserved area addresses.
+  char* _low_boundary;
+  char* _high_boundary;
+
+  // The commit/uncommit granularity in bytes.
+  size_t _page_size;
+
+  // Bitmap used for verification of commit/uncommit operations.
+  BitMap _committed;
+
+  // Indicates that the entire space has been committed and pinned in memory,
+  // os::commit_memory() or os::uncommit_memory() have no function.
+  bool _special;
+
+  // Indicates whether the committed space should be executable.
+  bool _executable;
+
+  // Returns the index of the page which contains the given address.
+  uintptr_t  addr_to_page_index(char* addr) const;
+  // Returns the address of the given page index.
+  char*  page_start(uintptr_t index);
+  // Returns the byte size of the given number of pages.
+  size_t byte_size_for_pages(size_t num);
+
+  // Returns true if the entire area is backed by committed memory.
+  bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
+  // Returns true if the entire area is not backed by committed memory.
+  bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
+
+ public:
+
+  // Commit the given area of pages starting at start being size_in_pages large.
+  MemRegion commit(uintptr_t start, size_t size_in_pages);
+
+  // Uncommit the given area of pages starting at start being size_in_pages large.
+  MemRegion uncommit(uintptr_t start, size_t size_in_pages);
+
+  bool special() const { return _special; }
+
+  // Initialization
+  G1PageBasedVirtualSpace();
+  bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
+
+  // Destruction
+  ~G1PageBasedVirtualSpace();
+
+  // Amount of reserved memory.
+  size_t reserved_size() const;
+  // Memory used in this virtual space.
+  size_t committed_size() const;
+  // Memory left to use/expand in this virtual space.
+  size_t uncommitted_size() const;
+
+  bool contains(const void* p) const;
+
+  MemRegion reserved() {
+    MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
+    return x;
+  }
+
+  void release();
+
+  void check_for_contiguity() PRODUCT_RETURN;
+
+  // Debugging
+  void print_on(outputStream* out) PRODUCT_RETURN;
+  void print();
+};
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc_implementation/g1/g1BiasedArray.hpp"
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
+#include "runtime/virtualspace.hpp"
+#include "services/memTracker.hpp"
+#include "utilities/bitMap.inline.hpp"
+
+G1RegionToSpaceMapper::G1RegionToSpaceMapper(ReservedSpace rs,
+                                             size_t commit_granularity,
+                                             size_t region_granularity,
+                                             MemoryType type) :
+  _storage(),
+  _commit_granularity(commit_granularity),
+  _region_granularity(region_granularity),
+  _listener(NULL),
+  _commit_map() {
+  guarantee(is_power_of_2(commit_granularity), "must be");
+  guarantee(is_power_of_2(region_granularity), "must be");
+  _storage.initialize_with_granularity(rs, commit_granularity);
+
+  MemTracker::record_virtual_memory_type((address)rs.base(), type);
+}
+
+// G1RegionToSpaceMapper implementation where the region granularity is larger than
+// or the same as the commit granularity.
+// Basically, the space corresponding to one region region spans several OS pages.
+class G1RegionsLargerThanCommitSizeMapper : public G1RegionToSpaceMapper {
+ private:
+  size_t _pages_per_region;
+
+ public:
+  G1RegionsLargerThanCommitSizeMapper(ReservedSpace rs,
+                                      size_t os_commit_granularity,
+                                      size_t alloc_granularity,
+                                      size_t commit_factor,
+                                      MemoryType type) :
+     G1RegionToSpaceMapper(rs, os_commit_granularity, alloc_granularity, type),
+    _pages_per_region(alloc_granularity / (os_commit_granularity * commit_factor)) {
+
+    guarantee(alloc_granularity >= os_commit_granularity, "allocation granularity smaller than commit granularity");
+    _commit_map.resize(rs.size() * commit_factor / alloc_granularity, /* in_resource_area */ false);
+  }
+
+  virtual void commit_regions(uintptr_t start_idx, size_t num_regions) {
+    _storage.commit(start_idx * _pages_per_region, num_regions * _pages_per_region);
+    _commit_map.set_range(start_idx, start_idx + num_regions);
+    fire_on_commit(start_idx, num_regions);
+  }
+
+  virtual void uncommit_regions(uintptr_t start_idx, size_t num_regions) {
+    _storage.uncommit(start_idx * _pages_per_region, num_regions * _pages_per_region);
+    _commit_map.clear_range(start_idx, start_idx + num_regions);
+  }
+};
+
+// G1RegionToSpaceMapper implementation where the region granularity is smaller
+// than the commit granularity.
+// Basically, the contents of one OS page span several regions.
+class G1RegionsSmallerThanCommitSizeMapper : public G1RegionToSpaceMapper {
+ private:
+  class CommitRefcountArray : public G1BiasedMappedArray<uint> {
+   protected:
+     virtual uint default_value() const { return 0; }
+  };
+
+  size_t _regions_per_page;
+
+  CommitRefcountArray _refcounts;
+
+  uintptr_t region_idx_to_page_idx(uint region) const {
+    return region / _regions_per_page;
+  }
+
+ public:
+  G1RegionsSmallerThanCommitSizeMapper(ReservedSpace rs,
+                                       size_t os_commit_granularity,
+                                       size_t alloc_granularity,
+                                       size_t commit_factor,
+                                       MemoryType type) :
+     G1RegionToSpaceMapper(rs, os_commit_granularity, alloc_granularity, type),
+    _regions_per_page((os_commit_granularity * commit_factor) / alloc_granularity), _refcounts() {
+
+    guarantee((os_commit_granularity * commit_factor) >= alloc_granularity, "allocation granularity smaller than commit granularity");
+    _refcounts.initialize((HeapWord*)rs.base(), (HeapWord*)(rs.base() + rs.size()), os_commit_granularity);
+    _commit_map.resize(rs.size() * commit_factor / alloc_granularity, /* in_resource_area */ false);
+  }
+
+  virtual void commit_regions(uintptr_t start_idx, size_t num_regions) {
+    for (uintptr_t i = start_idx; i < start_idx + num_regions; i++) {
+      assert(!_commit_map.at(i), err_msg("Trying to commit storage at region "INTPTR_FORMAT" that is already committed", i));
+      uintptr_t idx = region_idx_to_page_idx(i);
+      uint old_refcount = _refcounts.get_by_index(idx);
+      if (old_refcount == 0) {
+        _storage.commit(idx, 1);
+      }
+      _refcounts.set_by_index(idx, old_refcount + 1);
+      _commit_map.set_bit(i);
+      fire_on_commit(i, 1);
+    }
+  }
+
+  virtual void uncommit_regions(uintptr_t start_idx, size_t num_regions) {
+    for (uintptr_t i = start_idx; i < start_idx + num_regions; i++) {
+      assert(_commit_map.at(i), err_msg("Trying to uncommit storage at region "INTPTR_FORMAT" that is not committed", i));
+      uintptr_t idx = region_idx_to_page_idx(i);
+      uint old_refcount = _refcounts.get_by_index(idx);
+      assert(old_refcount > 0, "must be");
+      if (old_refcount == 1) {
+        _storage.uncommit(idx, 1);
+      }
+      _refcounts.set_by_index(idx, old_refcount - 1);
+      _commit_map.clear_bit(i);
+    }
+  }
+};
+
+void G1RegionToSpaceMapper::fire_on_commit(uint start_idx, size_t num_regions) {
+  if (_listener != NULL) {
+    _listener->on_commit(start_idx, num_regions);
+  }
+}
+
+G1RegionToSpaceMapper* G1RegionToSpaceMapper::create_mapper(ReservedSpace rs,
+                                                            size_t os_commit_granularity,
+                                                            size_t region_granularity,
+                                                            size_t commit_factor,
+                                                            MemoryType type) {
+
+  if (region_granularity >= (os_commit_granularity * commit_factor)) {
+    return new G1RegionsLargerThanCommitSizeMapper(rs, os_commit_granularity, region_granularity, commit_factor, type);
+  } else {
+    return new G1RegionsSmallerThanCommitSizeMapper(rs, os_commit_granularity, region_granularity, commit_factor, type);
+  }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RegionToSpaceMapper.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP
+
+#include "gc_implementation/g1/g1PageBasedVirtualSpace.hpp"
+#include "utilities/debug.hpp"
+
+class G1MappingChangedListener VALUE_OBJ_CLASS_SPEC {
+ public:
+  // Fired after commit of the memory, i.e. the memory this listener is registered
+  // for can be accessed.
+  virtual void on_commit(uint start_idx, size_t num_regions) = 0;
+};
+
+// Maps region based commit/uncommit requests to the underlying page sized virtual
+// space.
+class G1RegionToSpaceMapper : public CHeapObj<mtGC> {
+ private:
+  G1MappingChangedListener* _listener;
+ protected:
+  // Backing storage.
+  G1PageBasedVirtualSpace _storage;
+  size_t _commit_granularity;
+  size_t _region_granularity;
+  // Mapping management
+  BitMap _commit_map;
+
+  G1RegionToSpaceMapper(ReservedSpace rs, size_t commit_granularity, size_t region_granularity, MemoryType type);
+
+  void fire_on_commit(uint start_idx, size_t num_regions);
+ public:
+  MemRegion reserved() { return _storage.reserved(); }
+
+  void set_mapping_changed_listener(G1MappingChangedListener* listener) { _listener = listener; }
+
+  virtual ~G1RegionToSpaceMapper() {
+    _commit_map.resize(0, /* in_resource_area */ false);
+  }
+
+  bool is_committed(uintptr_t idx) const {
+    return _commit_map.at(idx);
+  }
+
+  virtual void commit_regions(uintptr_t start_idx, size_t num_regions = 1) = 0;
+  virtual void uncommit_regions(uintptr_t start_idx, size_t num_regions = 1) = 0;
+
+  // Creates an appropriate G1RegionToSpaceMapper for the given parameters.
+  // The byte_translation_factor defines how many bytes in a region correspond to
+  // a single byte in the data structure this mapper is for.
+  // Eg. in the card table, this value corresponds to the size a single card
+  // table entry corresponds to.
+  static G1RegionToSpaceMapper* create_mapper(ReservedSpace rs,
+                                              size_t os_commit_granularity,
+                                              size_t region_granularity,
+                                              size_t byte_translation_factor,
+                                              MemoryType type);
+};
+
+#endif /* SHARE_VM_GC_IMPLEMENTATION_G1_G1REGIONTOSPACEMAPPER_HPP */
--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -540,6 +540,12 @@
 
 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i,
                            bool check_for_refs_into_cset) {
+  assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)),
+         err_msg("Card at "PTR_FORMAT" index "SIZE_FORMAT" representing heap at "PTR_FORMAT" (%u) must be in committed heap",
+                 p2i(card_ptr),
+                 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)),
+                 _ct_bs->addr_for(card_ptr),
+                 _g1->addr_to_region(_ct_bs->addr_for(card_ptr))));
 
   // If the card is no longer dirty, nothing to do.
   if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
--- a/hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "gc_implementation/g1/satbQueue.hpp"
@@ -38,7 +39,6 @@
   _kind = G1SATBCT;
 }
 
-
 void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
   // Nulls should have been already filtered.
   assert(pre_val->is_oop(true), "Error");
@@ -125,13 +125,52 @@
 }
 #endif
 
+void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions) {
+  MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
+  _card_table->clear(mr);
+}
+
 G1SATBCardTableLoggingModRefBS::
 G1SATBCardTableLoggingModRefBS(MemRegion whole_heap,
                                int max_covered_regions) :
   G1SATBCardTableModRefBS(whole_heap, max_covered_regions),
-  _dcqs(JavaThread::dirty_card_queue_set())
+  _dcqs(JavaThread::dirty_card_queue_set()),
+  _listener()
 {
   _kind = G1SATBCTLogging;
+  _listener.set_card_table(this);
+}
+
+void G1SATBCardTableLoggingModRefBS::initialize(G1RegionToSpaceMapper* mapper) {
+  mapper->set_mapping_changed_listener(&_listener);
+
+  _byte_map_size = mapper->reserved().byte_size();
+
+  _guard_index = cards_required(_whole_heap.word_size()) - 1;
+  _last_valid_index = _guard_index - 1;
+
+  HeapWord* low_bound  = _whole_heap.start();
+  HeapWord* high_bound = _whole_heap.end();
+
+  _cur_covered_regions = 1;
+  _covered[0] = _whole_heap;
+
+  _byte_map = (jbyte*) mapper->reserved().start();
+  byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
+  assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
+  assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
+
+  if (TraceCardTableModRefBS) {
+    gclog_or_tty->print_cr("G1SATBCardTableModRefBS::G1SATBCardTableModRefBS: ");
+    gclog_or_tty->print_cr("  "
+                  "  &_byte_map[0]: " INTPTR_FORMAT
+                  "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
+                  p2i(&_byte_map[0]),
+                  p2i(&_byte_map[_last_valid_index]));
+    gclog_or_tty->print_cr("  "
+                  "  byte_map_base: " INTPTR_FORMAT,
+                  p2i(byte_map_base));
+  }
 }
 
 void
--- a/hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1SATBCARDTABLEMODREFBS_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1SATBCARDTABLEMODREFBS_HPP
 
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
 #include "memory/cardTableModRefBS.hpp"
 #include "memory/memRegion.hpp"
 #include "oops/oop.inline.hpp"
@@ -33,6 +34,7 @@
 #if INCLUDE_ALL_GCS
 
 class DirtyCardQueueSet;
+class G1SATBCardTableLoggingModRefBS;
 
 // This barrier is specialized to use a logging barrier to support
 // snapshot-at-the-beginning marking.
@@ -126,18 +128,40 @@
     jbyte val = _byte_map[card_index];
     return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();
   }
+};
 
+class G1SATBCardTableLoggingModRefBSChangedListener : public G1MappingChangedListener {
+ private:
+  G1SATBCardTableLoggingModRefBS* _card_table;
+ public:
+  G1SATBCardTableLoggingModRefBSChangedListener() : _card_table(NULL) { }
+
+  void set_card_table(G1SATBCardTableLoggingModRefBS* card_table) { _card_table = card_table; }
+
+  virtual void on_commit(uint start_idx, size_t num_regions);
 };
 
 // Adds card-table logging to the post-barrier.
 // Usual invariant: all dirty cards are logged in the DirtyCardQueueSet.
 class G1SATBCardTableLoggingModRefBS: public G1SATBCardTableModRefBS {
+  friend class G1SATBCardTableLoggingModRefBSChangedListener;
  private:
+  G1SATBCardTableLoggingModRefBSChangedListener _listener;
   DirtyCardQueueSet& _dcqs;
  public:
+  static size_t compute_size(size_t mem_region_size_in_words) {
+    size_t number_of_slots = (mem_region_size_in_words / card_size_in_words);
+    return ReservedSpace::allocation_align_size_up(number_of_slots);
+  }
+
   G1SATBCardTableLoggingModRefBS(MemRegion whole_heap,
                                  int max_covered_regions);
 
+  virtual void initialize() { }
+  virtual void initialize(G1RegionToSpaceMapper* mapper);
+
+  virtual void resize_covered_region(MemRegion new_region) { ShouldNotReachHere(); }
+
   bool is_a(BarrierSet::Name bsn) {
     return bsn == BarrierSet::G1SATBCTLogging ||
       G1SATBCardTableModRefBS::is_a(bsn);
@@ -154,8 +178,6 @@
 
   void write_region_work(MemRegion mr)    { invalidate(mr); }
   void write_ref_array_work(MemRegion mr) { invalidate(mr); }
-
-
 };
 
 
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -345,11 +345,6 @@
   return low;
 }
 
-#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
-#pragma warning( disable:4355 ) // 'this' : used in base member initializer list
-#endif // _MSC_VER
-
-
 HeapRegion::HeapRegion(uint hrs_index,
                        G1BlockOffsetSharedArray* sharedOffsetArray,
                        MemRegion mr) :
@@ -361,7 +356,7 @@
     _claimed(InitialClaimValue), _evacuation_failed(false),
     _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
     _young_type(NotYoung), _next_young_region(NULL),
-    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
+    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
 #ifdef ASSERT
     _containing_set(NULL),
 #endif // ASSERT
@@ -370,14 +365,20 @@
     _predicted_bytes_to_copy(0)
 {
   _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
+  assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
+
+  initialize(mr);
+}
+
+void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
+  assert(_rem_set->is_empty(), "Remembered set must be empty");
+
+  G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
+
   _orig_end = mr.end();
-  // Note that initialize() will set the start of the unmarked area of the
-  // region.
   hr_clear(false /*par*/, false /*clear_space*/);
   set_top(bottom());
   record_top_and_timestamp();
-
-  assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
 }
 
 CompactibleSpace* HeapRegion::next_compaction_space() const {
@@ -905,7 +906,7 @@
     }
 
     // If it returns false, verify_for_object() will output the
-    // appropriate messasge.
+    // appropriate message.
     if (do_bot_verify &&
         !g1->is_obj_dead(obj, this) &&
         !_offsets.verify_for_object(p, obj_size)) {
@@ -1036,8 +1037,7 @@
   set_top(bottom());
   set_saved_mark_word(bottom());
   CompactibleSpace::clear(mangle_space);
-  _offsets.zero_bottom_entry();
-  _offsets.initialize_threshold();
+  reset_bot();
 }
 
 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
@@ -1127,9 +1127,11 @@
   _gc_time_stamp(0)
 {
   _offsets.set_space(this);
-  // false ==> we'll do the clearing if there's clearing to be done.
-  CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle);
+}
+
+void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
+  CompactibleSpace::initialize(mr, clear_space, mangle_space);
   _top = bottom();
-  _offsets.zero_bottom_entry();
-  _offsets.initialize_threshold();
+  reset_bot();
 }
+
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -62,7 +62,7 @@
                 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
 
 // sentinel value for hrs_index
-#define G1_NULL_HRS_INDEX ((uint) -1)
+#define G1_NO_HRS_INDEX ((uint) -1)
 
 // A dirty card to oop closure for heap regions. It
 // knows how to get the G1 heap and how to use the bitmap
@@ -146,6 +146,9 @@
   HeapWord* top() const { return _top; }
 
  protected:
+  // Reset the G1OffsetTableContigSpace.
+  virtual void initialize(MemRegion mr, bool clear_space, bool mangle_space);
+
   HeapWord** top_addr() { return &_top; }
   // Allocation helpers (return NULL if full).
   inline HeapWord* allocate_impl(size_t word_size, HeapWord* end_value);
@@ -200,8 +203,7 @@
   virtual void print() const;
 
   void reset_bot() {
-    _offsets.zero_bottom_entry();
-    _offsets.initialize_threshold();
+    _offsets.reset_bot();
   }
 
   void update_bot_for_object(HeapWord* start, size_t word_size) {
@@ -264,7 +266,6 @@
 #ifdef ASSERT
   HeapRegionSetBase* _containing_set;
 #endif // ASSERT
-  bool _pending_removal;
 
   // For parallel heapRegion traversal.
   jint _claimed;
@@ -333,6 +334,12 @@
              G1BlockOffsetSharedArray* sharedOffsetArray,
              MemRegion mr);
 
+  // Initializing the HeapRegion not only resets the data structure, but also
+  // resets the BOT for that heap region.
+  // The default values for clear_space means that we will do the clearing if
+  // there's clearing to be done ourselves. We also always mangle the space.
+  virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
+
   static int    LogOfHRGrainBytes;
   static int    LogOfHRGrainWords;
 
@@ -553,26 +560,6 @@
   // to provide a dummy version of it.
 #endif // ASSERT
 
-  // If we want to remove regions from a list in bulk we can simply tag
-  // them with the pending_removal tag and call the
-  // remove_all_pending() method on the list.
-
-  bool pending_removal() { return _pending_removal; }
-
-  void set_pending_removal(bool pending_removal) {
-    if (pending_removal) {
-      assert(!_pending_removal && containing_set() != NULL,
-             "can only set pending removal to true if it's false and "
-             "the region belongs to a region set");
-    } else {
-      assert( _pending_removal && containing_set() == NULL,
-              "can only set pending removal to false if it's true and "
-              "the region does not belong to a region set");
-    }
-
-    _pending_removal = pending_removal;
-  }
-
   HeapRegion* get_next_young_region() { return _next_young_region; }
   void set_next_young_region(HeapRegion* hr) {
     _next_young_region = hr;
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -373,17 +373,17 @@
                                                        _max_regions,
                                                        &_static_mem_size);
 
-  for (uint i = 0; i < n_par_rs; i++) {
-    for (uint j = 0; j < _max_regions; j++) {
-      set(i, j, InvalidCard);
-    }
-  }
+  invalidate(0, _max_regions);
 }
 
-void FromCardCache::shrink(uint new_num_regions) {
+void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) {
+  guarantee((size_t)start_idx + new_num_regions <= max_uintx,
+            err_msg("Trying to invalidate beyond maximum region, from %u size "SIZE_FORMAT,
+                    start_idx, new_num_regions));
   for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
-    assert(new_num_regions <= _max_regions, "Must be within max.");
-    for (uint j = new_num_regions; j < _max_regions; j++) {
+    uint end_idx = (start_idx + (uint)new_num_regions);
+    assert(end_idx <= _max_regions, "Must be within max.");
+    for (uint j = start_idx; j < end_idx; j++) {
       set(i, j, InvalidCard);
     }
   }
@@ -407,12 +407,12 @@
   }
 }
 
-void OtherRegionsTable::init_from_card_cache(uint max_regions) {
+void OtherRegionsTable::initialize(uint max_regions) {
   FromCardCache::initialize(HeapRegionRemSet::num_par_rem_sets(), max_regions);
 }
 
-void OtherRegionsTable::shrink_from_card_cache(uint new_num_regions) {
-  FromCardCache::shrink(new_num_regions);
+void OtherRegionsTable::invalidate(uint start_idx, size_t num_regions) {
+  FromCardCache::invalidate(start_idx, num_regions);
 }
 
 void OtherRegionsTable::print_from_card_cache() {
@@ -841,7 +841,7 @@
                                    HeapRegion* hr)
   : _bosa(bosa),
     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrs_index()), true),
-    _code_roots(), _other_regions(hr, &_m) {
+    _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
   reset_for_par_iteration();
 }
 
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -84,7 +84,7 @@
 
   static void initialize(uint n_par_rs, uint max_num_regions);
 
-  static void shrink(uint new_num_regions);
+  static void invalidate(uint start_idx, size_t num_regions);
 
   static void print(outputStream* out = gclog_or_tty) PRODUCT_RETURN;
 
@@ -213,11 +213,11 @@
 
   // Declare the heap size (in # of regions) to the OtherRegionsTable.
   // (Uses it to initialize from_card_cache).
-  static void init_from_card_cache(uint max_regions);
+  static void initialize(uint max_regions);
 
-  // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
-  // Make sure any entries for higher regions are invalid.
-  static void shrink_from_card_cache(uint new_num_regions);
+  // Declares that regions between start_idx <= i < start_idx + num_regions are
+  // not in use. Make sure that any entries for these regions are invalid.
+  static void invalidate(uint start_idx, size_t num_regions);
 
   static void print_from_card_cache();
 };
@@ -400,12 +400,11 @@
   // Declare the heap size (in # of regions) to the HeapRegionRemSet(s).
   // (Uses it to initialize from_card_cache).
   static void init_heap(uint max_regions) {
-    OtherRegionsTable::init_from_card_cache(max_regions);
+    OtherRegionsTable::initialize(max_regions);
   }
 
-  // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
-  static void shrink_heap(uint new_n_regs) {
-    OtherRegionsTable::shrink_from_card_cache(new_n_regs);
+  static void invalidate(uint start_idx, uint num_regions) {
+    OtherRegionsTable::invalidate(start_idx, num_regions);
   }
 
 #ifndef PRODUCT
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -25,163 +25,204 @@
 #include "precompiled.hpp"
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
-#include "gc_implementation/g1/heapRegionSet.hpp"
+#include "gc_implementation/g1/heapRegionSet.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
+#include "gc_implementation/g1/concurrentG1Refine.hpp"
 #include "memory/allocation.hpp"
 
-// Private
+void HeapRegionSeq::initialize(G1RegionToSpaceMapper* heap_storage,
+                               G1RegionToSpaceMapper* prev_bitmap,
+                               G1RegionToSpaceMapper* next_bitmap,
+                               G1RegionToSpaceMapper* bot,
+                               G1RegionToSpaceMapper* cardtable,
+                               G1RegionToSpaceMapper* card_counts) {
+  _allocated_heapregions_length = 0;
 
-uint HeapRegionSeq::find_contiguous_from(uint from, uint num) {
-  uint len = length();
-  assert(num > 1, "use this only for sequences of length 2 or greater");
-  assert(from <= len,
-         err_msg("from: %u should be valid and <= than %u", from, len));
+  _heap_mapper = heap_storage;
 
-  uint curr = from;
-  uint first = G1_NULL_HRS_INDEX;
-  uint num_so_far = 0;
-  while (curr < len && num_so_far < num) {
-    if (at(curr)->is_empty()) {
-      if (first == G1_NULL_HRS_INDEX) {
-        first = curr;
-        num_so_far = 1;
-      } else {
-        num_so_far += 1;
-      }
-    } else {
-      first = G1_NULL_HRS_INDEX;
-      num_so_far = 0;
+  _prev_bitmap_mapper = prev_bitmap;
+  _next_bitmap_mapper = next_bitmap;
+
+  _bot_mapper = bot;
+  _cardtable_mapper = cardtable;
+
+  _card_counts_mapper = card_counts;
+
+  MemRegion reserved = heap_storage->reserved();
+  _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
+
+  _available_map.resize(_regions.length(), false);
+  _available_map.clear();
+}
+
+bool HeapRegionSeq::is_available(uint region) const {
+  return _available_map.at(region);
+}
+
+#ifdef ASSERT
+bool HeapRegionSeq::is_free(HeapRegion* hr) const {
+  return _free_list.contains(hr);
+}
+#endif
+
+HeapRegion* HeapRegionSeq::new_heap_region(uint hrs_index) {
+  HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(hrs_index);
+  MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
+  assert(reserved().contains(mr), "invariant");
+  return new HeapRegion(hrs_index, G1CollectedHeap::heap()->bot_shared(), mr);
+}
+
+void HeapRegionSeq::commit_regions(uint index, size_t num_regions) {
+  guarantee(num_regions > 0, "Must commit more than zero regions");
+  guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
+
+  _num_committed += (uint)num_regions;
+
+  _heap_mapper->commit_regions(index, num_regions);
+
+  // Also commit auxiliary data
+  _prev_bitmap_mapper->commit_regions(index, num_regions);
+  _next_bitmap_mapper->commit_regions(index, num_regions);
+
+  _bot_mapper->commit_regions(index, num_regions);
+  _cardtable_mapper->commit_regions(index, num_regions);
+
+  _card_counts_mapper->commit_regions(index, num_regions);
+}
+
+void HeapRegionSeq::uncommit_regions(uint start, size_t num_regions) {
+  guarantee(num_regions >= 1, err_msg("Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start));
+  guarantee(_num_committed >= num_regions, "pre-condition");
+
+  // Print before uncommitting.
+  if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
+    for (uint i = start; i < start + num_regions; i++) {
+      HeapRegion* hr = at(i);
+      G1CollectedHeap::heap()->hr_printer()->uncommit(hr->bottom(), hr->end());
     }
-    curr += 1;
   }
-  assert(num_so_far <= num, "post-condition");
-  if (num_so_far == num) {
-    // we found enough space for the humongous object
-    assert(from <= first && first < len, "post-condition");
-    assert(first < curr && (curr - first) == num, "post-condition");
-    for (uint i = first; i < first + num; ++i) {
-      assert(at(i)->is_empty(), "post-condition");
+
+  _num_committed -= (uint)num_regions;
+
+  _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
+  _heap_mapper->uncommit_regions(start, num_regions);
+
+  // Also uncommit auxiliary data
+  _prev_bitmap_mapper->uncommit_regions(start, num_regions);
+  _next_bitmap_mapper->uncommit_regions(start, num_regions);
+
+  _bot_mapper->uncommit_regions(start, num_regions);
+  _cardtable_mapper->uncommit_regions(start, num_regions);
+
+  _card_counts_mapper->uncommit_regions(start, num_regions);
+}
+
+void HeapRegionSeq::make_regions_available(uint start, uint num_regions) {
+  guarantee(num_regions > 0, "No point in calling this for zero regions");
+  commit_regions(start, num_regions);
+  for (uint i = start; i < start + num_regions; i++) {
+    if (_regions.get_by_index(i) == NULL) {
+      HeapRegion* new_hr = new_heap_region(i);
+      _regions.set_by_index(i, new_hr);
+      _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
     }
-    return first;
-  } else {
-    // we failed to find enough space for the humongous object
-    return G1_NULL_HRS_INDEX;
+  }
+
+  _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
+
+  for (uint i = start; i < start + num_regions; i++) {
+    assert(is_available(i), err_msg("Just made region %u available but is apparently not.", i));
+    HeapRegion* hr = at(i);
+    if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
+      G1CollectedHeap::heap()->hr_printer()->commit(hr->bottom(), hr->end());
+    }
+    HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
+    MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
+
+    hr->initialize(mr);
+    insert_into_free_list(at(i));
   }
 }
 
-// Public
-
-void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* end) {
-  assert((uintptr_t) bottom % HeapRegion::GrainBytes == 0,
-         "bottom should be heap region aligned");
-  assert((uintptr_t) end % HeapRegion::GrainBytes == 0,
-         "end should be heap region aligned");
-
-  _next_search_index = 0;
-  _allocated_length = 0;
-
-  _regions.initialize(bottom, end, HeapRegion::GrainBytes);
+uint HeapRegionSeq::expand_by(uint num_regions) {
+  return expand_at(0, num_regions);
 }
 
-MemRegion HeapRegionSeq::expand_by(HeapWord* old_end,
-                                   HeapWord* new_end,
-                                   FreeRegionList* list) {
-  assert(old_end < new_end, "don't call it otherwise");
-  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+uint HeapRegionSeq::expand_at(uint start, uint num_regions) {
+  if (num_regions == 0) {
+    return 0;
+  }
 
-  HeapWord* next_bottom = old_end;
-  assert(heap_bottom() <= next_bottom, "invariant");
-  while (next_bottom < new_end) {
-    assert(next_bottom < heap_end(), "invariant");
-    uint index = length();
+  uint cur = start;
+  uint idx_last_found = 0;
+  uint num_last_found = 0;
 
-    assert(index < max_length(), "otherwise we cannot expand further");
-    if (index == 0) {
-      // We have not allocated any regions so far
-      assert(next_bottom == heap_bottom(), "invariant");
-    } else {
-      // next_bottom should match the end of the last/previous region
-      assert(next_bottom == at(index - 1)->end(), "invariant");
-    }
+  uint expanded = 0;
 
-    if (index == _allocated_length) {
-      // We have to allocate a new HeapRegion.
-      HeapRegion* new_hr = g1h->new_heap_region(index, next_bottom);
-      if (new_hr == NULL) {
-        // allocation failed, we bail out and return what we have done so far
-        return MemRegion(old_end, next_bottom);
-      }
-      assert(_regions.get_by_index(index) == NULL, "invariant");
-      _regions.set_by_index(index, new_hr);
-      increment_allocated_length();
-    }
-    // Have to increment the length first, otherwise we will get an
-    // assert failure at(index) below.
-    increment_length();
-    HeapRegion* hr = at(index);
-    list->add_as_tail(hr);
+  while (expanded < num_regions &&
+         (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
+    uint to_expand = MIN2(num_regions - expanded, num_last_found);
+    make_regions_available(idx_last_found, to_expand);
+    expanded += to_expand;
+    cur = idx_last_found + num_last_found + 1;
+  }
 
-    next_bottom = hr->end();
-  }
-  assert(next_bottom == new_end, "post-condition");
-  return MemRegion(old_end, next_bottom);
+  verify_optional();
+  return expanded;
 }
 
-uint HeapRegionSeq::free_suffix() {
-  uint res = 0;
-  uint index = length();
-  while (index > 0) {
-    index -= 1;
-    if (!at(index)->is_empty()) {
-      break;
+uint HeapRegionSeq::find_contiguous(size_t num, bool empty_only) {
+  uint found = 0;
+  size_t length_found = 0;
+  uint cur = 0;
+
+  while (length_found < num && cur < max_length()) {
+    HeapRegion* hr = _regions.get_by_index(cur);
+    if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
+      // This region is a potential candidate for allocation into.
+      length_found++;
+    } else {
+      // This region is not a candidate. The next region is the next possible one.
+      found = cur + 1;
+      length_found = 0;
     }
-    res += 1;
+    cur++;
   }
-  return res;
+
+  if (length_found == num) {
+    for (uint i = found; i < (found + num); i++) {
+      HeapRegion* hr = _regions.get_by_index(i);
+      // sanity check
+      guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
+                err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
+                        " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));
+    }
+    return found;
+  } else {
+    return G1_NO_HRS_INDEX;
+  }
 }
 
-uint HeapRegionSeq::find_contiguous(uint num) {
-  assert(num > 1, "use this only for sequences of length 2 or greater");
-  assert(_next_search_index <= length(),
-         err_msg("_next_search_index: %u should be valid and <= than %u",
-                 _next_search_index, length()));
-
-  uint start = _next_search_index;
-  uint res = find_contiguous_from(start, num);
-  if (res == G1_NULL_HRS_INDEX && start > 0) {
-    // Try starting from the beginning. If _next_search_index was 0,
-    // no point in doing this again.
-    res = find_contiguous_from(0, num);
+HeapRegion* HeapRegionSeq::next_region_in_heap(const HeapRegion* r) const {
+  guarantee(r != NULL, "Start region must be a valid region");
+  guarantee(is_available(r->hrs_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrs_index()));
+  for (uint i = r->hrs_index() + 1; i < _allocated_heapregions_length; i++) {
+    HeapRegion* hr = _regions.get_by_index(i);
+    if (is_available(i)) {
+      return hr;
+    }
   }
-  if (res != G1_NULL_HRS_INDEX) {
-    assert(res < length(), err_msg("res: %u should be valid", res));
-    _next_search_index = res + num;
-    assert(_next_search_index <= length(),
-           err_msg("_next_search_index: %u should be valid and <= than %u",
-                   _next_search_index, length()));
-  }
-  return res;
+  return NULL;
 }
 
 void HeapRegionSeq::iterate(HeapRegionClosure* blk) const {
-  iterate_from((HeapRegion*) NULL, blk);
-}
+  uint len = max_length();
 
-void HeapRegionSeq::iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const {
-  uint hr_index = 0;
-  if (hr != NULL) {
-    hr_index = hr->hrs_index();
-  }
-
-  uint len = length();
-  for (uint i = hr_index; i < len; i += 1) {
-    bool res = blk->doHeapRegion(at(i));
-    if (res) {
-      blk->incomplete();
-      return;
+  for (uint i = 0; i < len; i++) {
+    if (!is_available(i)) {
+      continue;
     }
-  }
-  for (uint i = 0; i < hr_index; i += 1) {
+    guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));
     bool res = blk->doHeapRegion(at(i));
     if (res) {
       blk->incomplete();
@@ -190,71 +231,220 @@
   }
 }
 
+uint HeapRegionSeq::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
+  guarantee(res_idx != NULL, "checking");
+  guarantee(start_idx <= (max_length() + 1), "checking");
+
+  uint num_regions = 0;
+
+  uint cur = start_idx;
+  while (cur < max_length() && is_available(cur)) {
+    cur++;
+  }
+  if (cur == max_length()) {
+    return num_regions;
+  }
+  *res_idx = cur;
+  while (cur < max_length() && !is_available(cur)) {
+    cur++;
+  }
+  num_regions = cur - *res_idx;
+#ifdef ASSERT
+  for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
+    assert(!is_available(i), "just checking");
+  }
+  assert(cur == max_length() || num_regions == 0 || is_available(cur),
+         err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
+#endif
+  return num_regions;
+}
+
+uint HeapRegionSeq::start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const {
+  return num_regions * worker_i / num_workers;
+}
+
+void HeapRegionSeq::par_iterate(HeapRegionClosure* blk, uint worker_id, uint num_workers, jint claim_value) const {
+  const uint start_index = start_region_for_worker(worker_id, num_workers, _allocated_heapregions_length);
+
+  // Every worker will actually look at all regions, skipping over regions that
+  // are currently not committed.
+  // This also (potentially) iterates over regions newly allocated during GC. This
+  // is no problem except for some extra work.
+  for (uint count = 0; count < _allocated_heapregions_length; count++) {
+    const uint index = (start_index + count) % _allocated_heapregions_length;
+    assert(0 <= index && index < _allocated_heapregions_length, "sanity");
+    // Skip over unavailable regions
+    if (!is_available(index)) {
+      continue;
+    }
+    HeapRegion* r = _regions.get_by_index(index);
+    // We'll ignore "continues humongous" regions (we'll process them
+    // when we come across their corresponding "start humongous"
+    // region) and regions already claimed.
+    if (r->claim_value() == claim_value || r->continuesHumongous()) {
+      continue;
+    }
+    // OK, try to claim it
+    if (!r->claimHeapRegion(claim_value)) {
+      continue;
+    }
+    // Success!
+    if (r->startsHumongous()) {
+      // If the region is "starts humongous" we'll iterate over its
+      // "continues humongous" first; in fact we'll do them
+      // first. The order is important. In one case, calling the
+      // closure on the "starts humongous" region might de-allocate
+      // and clear all its "continues humongous" regions and, as a
+      // result, we might end up processing them twice. So, we'll do
+      // them first (note: most closures will ignore them anyway) and
+      // then we'll do the "starts humongous" region.
+      for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {
+        HeapRegion* chr = _regions.get_by_index(ch_index);
+
+        assert(chr->continuesHumongous(), "Must be humongous region");
+        assert(chr->humongous_start_region() == r,
+               err_msg("Must work on humongous continuation of the original start region "
+                       PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
+        assert(chr->claim_value() != claim_value,
+               "Must not have been claimed yet because claiming of humongous continuation first claims the start region");
+
+        bool claim_result = chr->claimHeapRegion(claim_value);
+        // We should always be able to claim it; no one else should
+        // be trying to claim this region.
+        guarantee(claim_result, "We should always be able to claim the continuesHumongous part of the humongous object");
+
+        bool res2 = blk->doHeapRegion(chr);
+        if (res2) {
+          return;
+        }
+
+        // Right now, this holds (i.e., no closure that actually
+        // does something with "continues humongous" regions
+        // clears them). We might have to weaken it in the future,
+        // but let's leave these two asserts here for extra safety.
+        assert(chr->continuesHumongous(), "should still be the case");
+        assert(chr->humongous_start_region() == r, "sanity");
+      }
+    }
+
+    bool res = blk->doHeapRegion(r);
+    if (res) {
+      return;
+    }
+  }
+}
+
 uint HeapRegionSeq::shrink_by(uint num_regions_to_remove) {
-  // Reset this in case it's currently pointing into the regions that
-  // we just removed.
-  _next_search_index = 0;
-
   assert(length() > 0, "the region sequence should not be empty");
-  assert(length() <= _allocated_length, "invariant");
-  assert(_allocated_length > 0, "we should have at least one region committed");
+  assert(length() <= _allocated_heapregions_length, "invariant");
+  assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
   assert(num_regions_to_remove < length(), "We should never remove all regions");
 
-  uint i = 0;
-  for (; i < num_regions_to_remove; i++) {
-    HeapRegion* cur = at(length() - 1);
+  if (num_regions_to_remove == 0) {
+    return 0;
+  }
 
-    if (!cur->is_empty()) {
-      // We have to give up if the region can not be moved
-      break;
+  uint removed = 0;
+  uint cur = _allocated_heapregions_length - 1;
+  uint idx_last_found = 0;
+  uint num_last_found = 0;
+
+  while ((removed < num_regions_to_remove) &&
+      (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
+    // Only allow uncommit from the end of the heap.
+    if ((idx_last_found + num_last_found) != _allocated_heapregions_length) {
+      return 0;
+    }
+    uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
+
+    uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);
+
+    cur -= num_last_found;
+    removed += to_remove;
   }
-    assert(!cur->isHumongous(), "Humongous regions should not be empty");
 
-    decrement_length();
-  }
-  return i;
+  verify_optional();
+
+  return removed;
 }
 
-#ifndef PRODUCT
-void HeapRegionSeq::verify_optional() {
-  guarantee(length() <= _allocated_length,
+uint HeapRegionSeq::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
+  guarantee(start_idx < _allocated_heapregions_length, "checking");
+  guarantee(res_idx != NULL, "checking");
+
+  uint num_regions_found = 0;
+
+  jlong cur = start_idx;
+  while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
+    cur--;
+  }
+  if (cur == -1) {
+    return num_regions_found;
+  }
+  jlong old_cur = cur;
+  // cur indexes the first empty region
+  while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
+    cur--;
+  }
+  *res_idx = cur + 1;
+  num_regions_found = old_cur - cur;
+
+#ifdef ASSERT
+  for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
+    assert(at(i)->is_empty(), "just checking");
+  }
+#endif
+  return num_regions_found;
+}
+
+void HeapRegionSeq::verify() {
+  guarantee(length() <= _allocated_heapregions_length,
             err_msg("invariant: _length: %u _allocated_length: %u",
-                    length(), _allocated_length));
-  guarantee(_allocated_length <= max_length(),
+                    length(), _allocated_heapregions_length));
+  guarantee(_allocated_heapregions_length <= max_length(),
             err_msg("invariant: _allocated_length: %u _max_length: %u",
-                    _allocated_length, max_length()));
-  guarantee(_next_search_index <= length(),
-            err_msg("invariant: _next_search_index: %u _length: %u",
-                    _next_search_index, length()));
+                    _allocated_heapregions_length, max_length()));
 
+  bool prev_committed = true;
+  uint num_committed = 0;
   HeapWord* prev_end = heap_bottom();
-  for (uint i = 0; i < _allocated_length; i += 1) {
+  for (uint i = 0; i < _allocated_heapregions_length; i++) {
+    if (!is_available(i)) {
+      prev_committed = false;
+      continue;
+    }
+    num_committed++;
     HeapRegion* hr = _regions.get_by_index(i);
     guarantee(hr != NULL, err_msg("invariant: i: %u", i));
-    guarantee(hr->bottom() == prev_end,
+    guarantee(!prev_committed || hr->bottom() == prev_end,
               err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
                       i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));
     guarantee(hr->hrs_index() == i,
               err_msg("invariant: i: %u hrs_index(): %u", i, hr->hrs_index()));
-    if (i < length()) {
-      // Asserts will fire if i is >= _length
-      HeapWord* addr = hr->bottom();
-      guarantee(addr_to_region(addr) == hr, "sanity");
-    } else {
-      guarantee(hr->is_empty(), "sanity");
-      guarantee(!hr->isHumongous(), "sanity");
-      // using assert instead of guarantee here since containing_set()
-      // is only available in non-product builds.
-      assert(hr->containing_set() == NULL, "sanity");
-    }
+    // Asserts will fire if i is >= _length
+    HeapWord* addr = hr->bottom();
+    guarantee(addr_to_region(addr) == hr, "sanity");
+    // We cannot check whether the region is part of a particular set: at the time
+    // this method may be called, we have only completed allocation of the regions,
+    // but not put into a region set.
+    prev_committed = true;
     if (hr->startsHumongous()) {
       prev_end = hr->orig_end();
     } else {
       prev_end = hr->end();
     }
   }
-  for (uint i = _allocated_length; i < max_length(); i += 1) {
+  for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
     guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));
   }
+
+  guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));
+  _free_list.verify();
+}
+
+#ifndef PRODUCT
+void HeapRegionSeq::verify_optional() {
+  verify();
 }
 #endif // PRODUCT
+
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -26,6 +26,8 @@
 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
 
 #include "gc_implementation/g1/g1BiasedArray.hpp"
+#include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
+#include "gc_implementation/g1/heapRegionSet.hpp"
 
 class HeapRegion;
 class HeapRegionClosure;
@@ -33,16 +35,20 @@
 
 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
  protected:
-   virtual HeapRegion* default_value() const { return NULL; }
+  virtual HeapRegion* default_value() const { return NULL; }
 };
 
-// This class keeps track of the region metadata (i.e., HeapRegion
-// instances). They are kept in the _regions array in address
-// order. A region's index in the array corresponds to its index in
-// the heap (i.e., 0 is the region at the bottom of the heap, 1 is
-// the one after it, etc.). Two regions that are consecutive in the
-// array should also be adjacent in the address space (i.e.,
-// region(i).end() == region(i+1).bottom().
+// This class keeps track of the actual heap memory, auxiliary data
+// and its metadata (i.e., HeapRegion instances) and the list of free regions.
+//
+// This allows maximum flexibility for deciding what to commit or uncommit given
+// a request from outside.
+//
+// HeapRegions are kept in the _regions array in address order. A region's
+// index in the array corresponds to its index in the heap (i.e., 0 is the
+// region at the bottom of the heap, 1 is the one after it, etc.). Two
+// regions that are consecutive in the array should also be adjacent in the
+// address space (i.e., region(i).end() == region(i+1).bottom().
 //
 // We create a HeapRegion when we commit the region's address space
 // for the first time. When we uncommit the address space of a
@@ -51,56 +57,94 @@
 //
 // We keep track of three lengths:
 //
-// * _committed_length (returned by length()) is the number of currently
-//   committed regions.
-// * _allocated_length (not exposed outside this class) is the
-//   number of regions for which we have HeapRegions.
+// * _num_committed (returned by length()) is the number of currently
+//   committed regions. These may not be contiguous.
+// * _allocated_heapregions_length (not exposed outside this class) is the
+//   number of regions+1 for which we have HeapRegions.
 // * max_length() returns the maximum number of regions the heap can have.
 //
-// and maintain that: _committed_length <= _allocated_length <= max_length()
 
 class HeapRegionSeq: public CHeapObj<mtGC> {
   friend class VMStructs;
 
   G1HeapRegionTable _regions;
 
-  // The number of regions committed in the heap.
-  uint _committed_length;
+  G1RegionToSpaceMapper* _heap_mapper;
+  G1RegionToSpaceMapper* _prev_bitmap_mapper;
+  G1RegionToSpaceMapper* _next_bitmap_mapper;
+  G1RegionToSpaceMapper* _bot_mapper;
+  G1RegionToSpaceMapper* _cardtable_mapper;
+  G1RegionToSpaceMapper* _card_counts_mapper;
 
-  // A hint for which index to start searching from for humongous
-  // allocations.
-  uint _next_search_index;
+  FreeRegionList _free_list;
 
-  // The number of regions for which we have allocated HeapRegions for.
-  uint _allocated_length;
+  // Each bit in this bitmap indicates that the corresponding region is available
+  // for allocation.
+  BitMap _available_map;
 
-  // Find a contiguous set of empty regions of length num, starting
-  // from the given index.
-  uint find_contiguous_from(uint from, uint num);
+   // The number of regions committed in the heap.
+  uint _num_committed;
 
-  void increment_allocated_length() {
-    assert(_allocated_length < max_length(), "pre-condition");
-    _allocated_length++;
-  }
-
-  void increment_length() {
-    assert(length() < max_length(), "pre-condition");
-    _committed_length++;
-  }
-
-  void decrement_length() {
-    assert(length() > 0, "pre-condition");
-    _committed_length--;
-  }
+  // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
+  uint _allocated_heapregions_length;
 
   HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
   HeapWord* heap_end() const {return _regions.end_address_mapped(); }
 
+  void make_regions_available(uint index, uint num_regions = 1);
+
+  // Pass down commit calls to the VirtualSpace.
+  void commit_regions(uint index, size_t num_regions = 1);
+  void uncommit_regions(uint index, size_t num_regions = 1);
+
+  // Notify other data structures about change in the heap layout.
+  void update_committed_space(HeapWord* old_end, HeapWord* new_end);
+  // Calculate the starting region for each worker during parallel iteration so
+  // that they do not all start from the same region.
+  uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const;
+
+  // Find a contiguous set of empty or uncommitted regions of length num and return
+  // the index of the first region or G1_NO_HRS_INDEX if the search was unsuccessful.
+  // If only_empty is true, only empty regions are considered.
+  // Searches from bottom to top of the heap, doing a first-fit.
+  uint find_contiguous(size_t num, bool only_empty);
+  // Finds the next sequence of unavailable regions starting from start_idx. Returns the
+  // length of the sequence found. If this result is zero, no such sequence could be found,
+  // otherwise res_idx indicates the start index of these regions.
+  uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
+  // Finds the next sequence of empty regions starting from start_idx, going backwards in
+  // the heap. Returns the length of the sequence found. If this value is zero, no
+  // sequence could be found, otherwise res_idx contains the start index of this range.
+  uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
+  // Allocate a new HeapRegion for the given index.
+  HeapRegion* new_heap_region(uint hrs_index);
+#ifdef ASSERT
+public:
+  bool is_free(HeapRegion* hr) const;
+#endif
+  // Returns whether the given region is available for allocation.
+  bool is_available(uint region) const;
+
  public:
   // Empty constructor, we'll initialize it with the initialize() method.
-  HeapRegionSeq() : _regions(), _committed_length(0), _next_search_index(0), _allocated_length(0) { }
+  HeapRegionSeq() : _regions(), _heap_mapper(NULL), _num_committed(0),
+                    _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),
+                    _allocated_heapregions_length(0), _available_map(),
+                    _free_list("Free list", new MasterFreeRegionListMtSafeChecker())
+  { }
 
-  void initialize(HeapWord* bottom, HeapWord* end);
+  void initialize(G1RegionToSpaceMapper* heap_storage,
+                  G1RegionToSpaceMapper* prev_bitmap,
+                  G1RegionToSpaceMapper* next_bitmap,
+                  G1RegionToSpaceMapper* bot,
+                  G1RegionToSpaceMapper* cardtable,
+                  G1RegionToSpaceMapper* card_counts);
+
+  // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
+  // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
+  // the heap from the lowest address, this region (and its associated data
+  // structures) are available and we do not need to check further.
+  HeapRegion* get_dummy_region() { return new_heap_region(0); }
 
   // Return the HeapRegion at the given index. Assume that the index
   // is valid.
@@ -110,45 +154,86 @@
   // HeapRegion, otherwise return NULL.
   inline HeapRegion* addr_to_region(HeapWord* addr) const;
 
+  // Insert the given region into the free region list.
+  inline void insert_into_free_list(HeapRegion* hr);
+
+  // Insert the given region list into the global free region list.
+  void insert_list_into_free_list(FreeRegionList* list) {
+    _free_list.add_ordered(list);
+  }
+
+  HeapRegion* allocate_free_region(bool is_old) {
+    HeapRegion* hr = _free_list.remove_region(is_old);
+
+    if (hr != NULL) {
+      assert(hr->next() == NULL, "Single region should not have next");
+      assert(is_available(hr->hrs_index()), "Must be committed");
+    }
+    return hr;
+  }
+
+  inline void allocate_free_regions_starting_at(uint first, uint num_regions);
+
+  // Remove all regions from the free list.
+  void remove_all_free_regions() {
+    _free_list.remove_all();
+  }
+
+  // Return the number of committed free regions in the heap.
+  uint num_free_regions() const {
+    return _free_list.length();
+  }
+
+  size_t total_capacity_bytes() const {
+    return num_free_regions() * HeapRegion::GrainBytes;
+  }
+
+  // Return the number of available (uncommitted) regions.
+  uint available() const { return max_length() - length(); }
+
   // Return the number of regions that have been committed in the heap.
-  uint length() const { return _committed_length; }
+  uint length() const { return _num_committed; }
 
   // Return the maximum number of regions in the heap.
   uint max_length() const { return (uint)_regions.length(); }
 
-  // Expand the sequence to reflect that the heap has grown from
-  // old_end to new_end. Either create new HeapRegions, or re-use
-  // existing ones, and return them in the given list. Returns the
-  // memory region that covers the newly-created regions. If a
-  // HeapRegion allocation fails, the result memory region might be
-  // smaller than the desired one.
-  MemRegion expand_by(HeapWord* old_end, HeapWord* new_end,
-                      FreeRegionList* list);
+  MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
 
-  // Return the number of contiguous regions at the end of the sequence
-  // that are available for allocation.
-  uint free_suffix();
+  // Expand the sequence to reflect that the heap has grown. Either create new
+  // HeapRegions, or re-use existing ones. Returns the number of regions the
+  // sequence was expanded by. If a HeapRegion allocation fails, the resulting
+  // number of regions might be smaller than what's desired.
+  uint expand_by(uint num_regions);
 
-  // Find a contiguous set of empty regions of length num and return
-  // the index of the first region or G1_NULL_HRS_INDEX if the
-  // search was unsuccessful.
-  uint find_contiguous(uint num);
+  // Makes sure that the regions from start to start+num_regions-1 are available
+  // for allocation. Returns the number of regions that were committed to achieve
+  // this.
+  uint expand_at(uint start, uint num_regions);
+
+  // Find a contiguous set of empty regions of length num. Returns the start index of
+  // that set, or G1_NO_HRS_INDEX.
+  uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
+  // Find a contiguous set of empty or unavailable regions of length num. Returns the
+  // start index of that set, or G1_NO_HRS_INDEX.
+  uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
+
+  HeapRegion* next_region_in_heap(const HeapRegion* r) const;
 
   // Apply blk->doHeapRegion() on all committed regions in address order,
   // terminating the iteration early if doHeapRegion() returns true.
   void iterate(HeapRegionClosure* blk) const;
 
-  // As above, but start the iteration from hr and loop around. If hr
-  // is NULL, we start from the first region in the heap.
-  void iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const;
+  void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const;
 
-  // Tag as uncommitted as many regions that are completely free as
-  // possible, up to num_regions_to_remove, from the suffix of the committed
-  // sequence. Return the actual number of removed regions.
+  // Uncommit up to num_regions_to_remove regions that are completely free.
+  // Return the actual number of uncommitted regions.
   uint shrink_by(uint num_regions_to_remove);
 
+  void verify();
+
   // Do some sanity checking.
   void verify_optional() PRODUCT_RETURN;
 };
 
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_HPP
+
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.inline.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSeq.inline.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -27,6 +27,7 @@
 
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "gc_implementation/g1/heapRegionSeq.hpp"
+#include "gc_implementation/g1/heapRegionSet.inline.hpp"
 
 inline HeapRegion* HeapRegionSeq::addr_to_region(HeapWord* addr) const {
   assert(addr < heap_end(),
@@ -35,16 +36,23 @@
         err_msg("addr: "PTR_FORMAT" bottom: "PTR_FORMAT, p2i(addr), p2i(heap_bottom())));
 
   HeapRegion* hr = _regions.get_by_address(addr);
-  assert(hr != NULL, "invariant");
   return hr;
 }
 
 inline HeapRegion* HeapRegionSeq::at(uint index) const {
-  assert(index < length(), "pre-condition");
+  assert(is_available(index), "pre-condition");
   HeapRegion* hr = _regions.get_by_index(index);
   assert(hr != NULL, "sanity");
   assert(hr->hrs_index() == index, "sanity");
   return hr;
 }
 
+inline void HeapRegionSeq::insert_into_free_list(HeapRegion* hr) {
+  _free_list.add_ordered(hr);
+}
+
+inline void HeapRegionSeq::allocate_free_regions_starting_at(uint first, uint num_regions) {
+  _free_list.remove_starting_at(at(first), num_regions);
+}
+
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSEQ_INLINE_HPP
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
 
@@ -67,7 +68,7 @@
   // Do the basic verification first before we do the checks over the regions.
   HeapRegionSetBase::verify();
 
-  _verify_in_progress        = true;
+  _verify_in_progress = true;
 }
 
 void HeapRegionSetBase::verify_end() {
@@ -103,62 +104,7 @@
 }
 
 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {
-  msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, head(), tail());
-}
-
-void FreeRegionList::add_as_head_or_tail(FreeRegionList* from_list, bool as_head) {
-  check_mt_safety();
-  from_list->check_mt_safety();
-
-  verify_optional();
-  from_list->verify_optional();
-
-  if (from_list->is_empty()) {
-    return;
-  }
-
-#ifdef ASSERT
-  FreeRegionListIterator iter(from_list);
-  while (iter.more_available()) {
-    HeapRegion* hr = iter.get_next();
-    // In set_containing_set() we check that we either set the value
-    // from NULL to non-NULL or vice versa to catch bugs. So, we have
-    // to NULL it first before setting it to the value.
-    hr->set_containing_set(NULL);
-    hr->set_containing_set(this);
-  }
-#endif // ASSERT
-
-  if (_head == NULL) {
-    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
-    _head = from_list->_head;
-    _tail = from_list->_tail;
-  } else {
-    assert(length() > 0 && _tail != NULL, hrs_ext_msg(this, "invariant"));
-    if (as_head) {
-      from_list->_tail->set_next(_head);
-      _head->set_prev(from_list->_tail);
-      _head = from_list->_head;
-    } else {
-      _tail->set_next(from_list->_head);
-      from_list->_head->set_prev(_tail);
-      _tail = from_list->_tail;
-    }
-  }
-
-  _count.increment(from_list->length(), from_list->total_capacity_bytes());
-  from_list->clear();
-
-  verify_optional();
-  from_list->verify_optional();
-}
-
-void FreeRegionList::add_as_head(FreeRegionList* from_list) {
-  add_as_head_or_tail(from_list, true /* as_head */);
-}
-
-void FreeRegionList::add_as_tail(FreeRegionList* from_list) {
-  add_as_head_or_tail(from_list, false /* as_head */);
+  msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, _head, _tail);
 }
 
 void FreeRegionList::remove_all() {
@@ -191,11 +137,6 @@
     return;
   }
 
-  if (is_empty()) {
-    add_as_head(from_list);
-    return;
-  }
-
   #ifdef ASSERT
   FreeRegionListIterator iter(from_list);
   while (iter.more_available()) {
@@ -208,39 +149,45 @@
   }
   #endif // ASSERT
 
-  HeapRegion* curr_to = _head;
-  HeapRegion* curr_from = from_list->_head;
+  if (is_empty()) {
+    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
+    _head = from_list->_head;
+    _tail = from_list->_tail;
+  } else {
+    HeapRegion* curr_to = _head;
+    HeapRegion* curr_from = from_list->_head;
 
-  while (curr_from != NULL) {
-    while (curr_to != NULL && curr_to->hrs_index() < curr_from->hrs_index()) {
-      curr_to = curr_to->next();
+    while (curr_from != NULL) {
+      while (curr_to != NULL && curr_to->hrs_index() < curr_from->hrs_index()) {
+        curr_to = curr_to->next();
+      }
+
+      if (curr_to == NULL) {
+        // The rest of the from list should be added as tail
+        _tail->set_next(curr_from);
+        curr_from->set_prev(_tail);
+        curr_from = NULL;
+      } else {
+        HeapRegion* next_from = curr_from->next();
+
+        curr_from->set_next(curr_to);
+        curr_from->set_prev(curr_to->prev());
+        if (curr_to->prev() == NULL) {
+          _head = curr_from;
+        } else {
+          curr_to->prev()->set_next(curr_from);
+        }
+        curr_to->set_prev(curr_from);
+
+        curr_from = next_from;
+      }
     }
 
-    if (curr_to == NULL) {
-      // The rest of the from list should be added as tail
-      _tail->set_next(curr_from);
-      curr_from->set_prev(_tail);
-      curr_from = NULL;
-    } else {
-      HeapRegion* next_from = curr_from->next();
-
-      curr_from->set_next(curr_to);
-      curr_from->set_prev(curr_to->prev());
-      if (curr_to->prev() == NULL) {
-        _head = curr_from;
-      } else {
-        curr_to->prev()->set_next(curr_from);
-      }
-      curr_to->set_prev(curr_from);
-
-      curr_from = next_from;
+    if (_tail->hrs_index() < from_list->_tail->hrs_index()) {
+      _tail = from_list->_tail;
     }
   }
 
-  if (_tail->hrs_index() < from_list->_tail->hrs_index()) {
-    _tail = from_list->_tail;
-  }
-
   _count.increment(from_list->length(), from_list->total_capacity_bytes());
   from_list->clear();
 
@@ -248,68 +195,59 @@
   from_list->verify_optional();
 }
 
-void FreeRegionList::remove_all_pending(uint target_count) {
+void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
   check_mt_safety();
-  assert(target_count > 1, hrs_ext_msg(this, "pre-condition"));
+  assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition"));
   assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));
 
   verify_optional();
   DEBUG_ONLY(uint old_length = length();)
 
-  HeapRegion* curr = _head;
+  HeapRegion* curr = first;
   uint count = 0;
-  while (curr != NULL) {
+  while (count < num_regions) {
     verify_region(curr);
     HeapRegion* next = curr->next();
     HeapRegion* prev = curr->prev();
 
-    if (curr->pending_removal()) {
-      assert(count < target_count,
-             hrs_err_msg("[%s] should not come across more regions "
-                         "pending for removal than target_count: %u",
-                         name(), target_count));
+    assert(count < num_regions,
+           hrs_err_msg("[%s] should not come across more regions "
+                       "pending for removal than num_regions: %u",
+                       name(), num_regions));
 
-      if (prev == NULL) {
-        assert(_head == curr, hrs_ext_msg(this, "invariant"));
-        _head = next;
-      } else {
-        assert(_head != curr, hrs_ext_msg(this, "invariant"));
-        prev->set_next(next);
-      }
-      if (next == NULL) {
-        assert(_tail == curr, hrs_ext_msg(this, "invariant"));
-        _tail = prev;
-      } else {
-        assert(_tail != curr, hrs_ext_msg(this, "invariant"));
-        next->set_prev(prev);
-      }
-      if (_last = curr) {
-        _last = NULL;
-      }
+    if (prev == NULL) {
+      assert(_head == curr, hrs_ext_msg(this, "invariant"));
+      _head = next;
+    } else {
+      assert(_head != curr, hrs_ext_msg(this, "invariant"));
+      prev->set_next(next);
+    }
+    if (next == NULL) {
+      assert(_tail == curr, hrs_ext_msg(this, "invariant"));
+      _tail = prev;
+    } else {
+      assert(_tail != curr, hrs_ext_msg(this, "invariant"));
+      next->set_prev(prev);
+    }
+    if (_last = curr) {
+      _last = NULL;
+    }
 
-      curr->set_next(NULL);
-      curr->set_prev(NULL);
-      remove(curr);
-      curr->set_pending_removal(false);
+    curr->set_next(NULL);
+    curr->set_prev(NULL);
+    remove(curr);
 
-      count += 1;
-
-      // If we have come across the target number of regions we can
-      // just bail out. However, for debugging purposes, we can just
-      // carry on iterating to make sure there are not more regions
-      // tagged with pending removal.
-      DEBUG_ONLY(if (count == target_count) break;)
-    }
+    count++;
     curr = next;
   }
 
-  assert(count == target_count,
-         hrs_err_msg("[%s] count: %u should be == target_count: %u",
-                     name(), count, target_count));
-  assert(length() + target_count == old_length,
+  assert(count == num_regions,
+         hrs_err_msg("[%s] count: %u should be == num_regions: %u",
+                     name(), count, num_regions));
+  assert(length() + num_regions == old_length,
          hrs_err_msg("[%s] new length should be consistent "
-                     "new length: %u old length: %u target_count: %u",
-                     name(), length(), old_length, target_count));
+                     "new length: %u old length: %u num_regions: %u",
+                     name(), length(), old_length, num_regions));
 
   verify_optional();
 }
@@ -348,10 +286,12 @@
       hr->print_on(out);
     }
   }
+
+  out->cr();
 }
 
 void FreeRegionList::verify_list() {
-  HeapRegion* curr = head();
+  HeapRegion* curr = _head;
   HeapRegion* prev1 = NULL;
   HeapRegion* prev0 = NULL;
   uint count = 0;
@@ -379,7 +319,7 @@
     curr = curr->next();
   }
 
-  guarantee(tail() == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), tail()->hrs_index(), prev0->hrs_index()));
+  guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrs_index(), prev0->hrs_index()));
   guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
   guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));
   guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
@@ -463,3 +403,41 @@
               "master humongous set MT safety protocol outside a safepoint");
   }
 }
+
+void FreeRegionList_test() {
+  FreeRegionList l("test");
+
+  const uint num_regions_in_test = 5;
+  // Create a fake heap. It does not need to be valid, as the HeapRegion constructor
+  // does not access it.
+  MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords);
+  // Allocate a fake BOT because the HeapRegion constructor initializes
+  // the BOT.
+  size_t bot_size = G1BlockOffsetSharedArray::compute_size(heap.word_size());
+  HeapWord* bot_data = NEW_C_HEAP_ARRAY(HeapWord, bot_size, mtGC);
+  ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(heap.word_size()));
+  G1RegionToSpaceMapper* bot_storage =
+    G1RegionToSpaceMapper::create_mapper(bot_rs,
+                                         os::vm_page_size(),
+                                         HeapRegion::GrainBytes,
+                                         G1BlockOffsetSharedArray::N_bytes,
+                                         mtGC);
+  G1BlockOffsetSharedArray oa(heap, bot_storage);
+  bot_storage->commit_regions(0, num_regions_in_test);
+  HeapRegion hr0(0, &oa, heap);
+  HeapRegion hr1(1, &oa, heap);
+  HeapRegion hr2(2, &oa, heap);
+  HeapRegion hr3(3, &oa, heap);
+  HeapRegion hr4(4, &oa, heap);
+  l.add_ordered(&hr1);
+  l.add_ordered(&hr0);
+  l.add_ordered(&hr3);
+  l.add_ordered(&hr4);
+  l.add_ordered(&hr2);
+  assert(l.length() == num_regions_in_test, "wrong length");
+  l.verify_list();
+
+  bot_storage->uncommit_regions(0, num_regions_in_test);
+  delete bot_storage;
+  FREE_C_HEAP_ARRAY(HeapWord, bot_data, mtGC);
+}
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -162,7 +162,7 @@
 // diagnosing failures.
 class hrs_ext_msg : public hrs_err_msg {
 public:
-  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("%s","") {
+  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("%s", "") {
     set->fill_in_ext_msg(this, message);
   }
 };
@@ -192,13 +192,9 @@
 };
 
 // A set that links all the regions added to it in a doubly-linked
-// list. We should try to avoid doing operations that iterate over
+// sorted list. We should try to avoid doing operations that iterate over
 // such lists in performance critical paths. Typically we should
-// add / remove one region at a time or concatenate two lists. There are
-// two ways to treat your lists, ordered and un-ordered. All un-ordered
-// operations are done in constant time. To keep a list ordered only use
-// add_ordered() to add elements to the list. If a list is not ordered
-// from start, there is no way to sort it later.
+// add / remove one region at a time or concatenate two lists.
 
 class FreeRegionListIterator;
 
@@ -210,13 +206,13 @@
   HeapRegion* _tail;
 
   // _last is used to keep track of where we added an element the last
-  // time in ordered lists. It helps to improve performance when adding
-  // several ordered items in a row.
+  // time. It helps to improve performance when adding several ordered items in a row.
   HeapRegion* _last;
 
   static uint _unrealistically_long_length;
 
-  void add_as_head_or_tail(FreeRegionList* from_list, bool as_head);
+  inline HeapRegion* remove_from_head_impl();
+  inline HeapRegion* remove_from_tail_impl();
 
 protected:
   virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);
@@ -232,8 +228,11 @@
 
   void verify_list();
 
-  HeapRegion* head() { return _head; }
-  HeapRegion* tail() { return _tail; }
+#ifdef ASSERT
+  bool contains(HeapRegion* hr) const {
+    return hr->containing_set() == this;
+  }
+#endif
 
   static void set_unrealistically_long_length(uint len);
 
@@ -242,55 +241,20 @@
   // is determined by hrs_index.
   inline void add_ordered(HeapRegion* hr);
 
-  // It adds hr to the list as the new head. The region should not be
-  // a member of another set.
-  inline void add_as_head(HeapRegion* hr);
-
-  // It adds hr to the list as the new tail. The region should not be
-  // a member of another set.
-  inline void add_as_tail(HeapRegion* hr);
-
-  // It removes and returns the head of the list. It assumes that the
-  // list is not empty so it will return a non-NULL value.
-  inline HeapRegion* remove_head();
-
-  // Convenience method.
-  inline HeapRegion* remove_head_or_null();
-
-  // Removes and returns the last element (_tail) of the list. It assumes
-  // that the list isn't empty so that it can return a non-NULL value.
-  inline HeapRegion* remove_tail();
-
-  // Convenience method
-  inline HeapRegion* remove_tail_or_null();
-
   // Removes from head or tail based on the given argument.
-  inline HeapRegion* remove_region(bool from_head);
+  HeapRegion* remove_region(bool from_head);
 
   // Merge two ordered lists. The result is also ordered. The order is
   // determined by hrs_index.
   void add_ordered(FreeRegionList* from_list);
 
-  // It moves the regions from from_list to this list and empties
-  // from_list. The new regions will appear in the same order as they
-  // were in from_list and be linked in the beginning of this list.
-  void add_as_head(FreeRegionList* from_list);
-
-  // It moves the regions from from_list to this list and empties
-  // from_list. The new regions will appear in the same order as they
-  // were in from_list and be linked in the end of this list.
-  void add_as_tail(FreeRegionList* from_list);
-
   // It empties the list by removing all regions from it.
   void remove_all();
 
-  // It removes all regions in the list that are pending for removal
-  // (i.e., they have been tagged with "pending_removal"). The list
-  // must not be empty, target_count should reflect the exact number
-  // of regions that are pending for removal in the list, and
-  // target_count should be > 1 (currently, we never need to remove a
-  // single region using this).
-  void remove_all_pending(uint target_count);
+  // Remove all (contiguous) regions from first to first + num_regions -1 from
+  // this list.
+  // Num_regions must be > 1.
+  void remove_starting_at(HeapRegion* first, uint num_regions);
 
   virtual void verify();
 
@@ -298,7 +262,7 @@
 };
 
 // Iterator class that provides a convenient way to iterate over the
-// regions of a HeapRegionLinkedList instance.
+// regions of a FreeRegionList.
 
 class FreeRegionListIterator : public StackObj {
 private:
@@ -324,7 +288,7 @@
   }
 
   FreeRegionListIterator(FreeRegionList* list) : _curr(NULL), _list(list) {
-    _curr = list->head();
+    _curr = list->_head;
   }
 };
 
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -30,7 +30,8 @@
 inline void HeapRegionSetBase::add(HeapRegion* hr) {
   check_mt_safety();
   assert(hr->containing_set() == NULL, hrs_ext_msg(this, "should not already have a containing set %u"));
-  assert(hr->next() == NULL && hr->prev() == NULL, hrs_ext_msg(this, "should not already be linked"));
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should not already be linked"));
+  assert(hr->prev() == NULL, hrs_ext_msg(this, "should not already be linked"));
 
   _count.increment(1u, hr->capacity());
   hr->set_containing_set(this);
@@ -40,7 +41,8 @@
 inline void HeapRegionSetBase::remove(HeapRegion* hr) {
   check_mt_safety();
   verify_region(hr);
-  assert(hr->next() == NULL && hr->prev() == NULL, hrs_ext_msg(this, "should already be unlinked"));
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should already be unlinked"));
+  assert(hr->prev() == NULL, hrs_ext_msg(this, "should already be unlinked"));
 
   hr->set_containing_set(NULL);
   assert(_count.length() > 0, hrs_ext_msg(this, "pre-condition"));
@@ -48,8 +50,7 @@
 }
 
 inline void FreeRegionList::add_ordered(HeapRegion* hr) {
-  check_mt_safety();
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
+  assert((length() == 0 && _head == NULL && _tail == NULL && _last == NULL) ||
          (length() >  0 && _head != NULL && _tail != NULL),
          hrs_ext_msg(this, "invariant"));
   // add() will verify the region and check mt safety.
@@ -95,55 +96,48 @@
   _last = hr;
 }
 
-inline void FreeRegionList::add_as_head(HeapRegion* hr) {
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
-         (length() >  0 && _head != NULL && _tail != NULL),
-         hrs_ext_msg(this, "invariant"));
-  // add() will verify the region and check mt safety.
-  add(hr);
-
-  // Now link the region.
-  if (_head != NULL) {
-    hr->set_next(_head);
-    _head->set_prev(hr);
-  } else {
-    _tail = hr;
-  }
-  _head = hr;
-}
-
-inline void FreeRegionList::add_as_tail(HeapRegion* hr) {
-  check_mt_safety();
-  assert((length() == 0 && _head == NULL && _tail == NULL) ||
-         (length() >  0 && _head != NULL && _tail != NULL),
-         hrs_ext_msg(this, "invariant"));
-  // add() will verify the region and check mt safety.
-  add(hr);
-
-  // Now link the region.
-  if (_tail != NULL) {
-    _tail->set_next(hr);
-    hr->set_prev(_tail);
-  } else {
-    _head = hr;
-  }
-  _tail = hr;
-}
-
-inline HeapRegion* FreeRegionList::remove_head() {
-  assert(!is_empty(), hrs_ext_msg(this, "the list should not be empty"));
-  assert(length() > 0 && _head != NULL && _tail != NULL,
-         hrs_ext_msg(this, "invariant"));
-
-  // We need to unlink it first.
-  HeapRegion* hr = _head;
-  _head = hr->next();
+inline HeapRegion* FreeRegionList::remove_from_head_impl() {
+  HeapRegion* result = _head;
+  _head = result->next();
   if (_head == NULL) {
     _tail = NULL;
   } else {
     _head->set_prev(NULL);
   }
-  hr->set_next(NULL);
+  result->set_next(NULL);
+  return result;
+}
+
+inline HeapRegion* FreeRegionList::remove_from_tail_impl() {
+  HeapRegion* result = _tail;
+
+  _tail = result->prev();
+  if (_tail == NULL) {
+    _head = NULL;
+  } else {
+    _tail->set_next(NULL);
+  }
+  result->set_prev(NULL);
+  return result;
+}
+
+inline HeapRegion* FreeRegionList::remove_region(bool from_head) {
+  check_mt_safety();
+  verify_optional();
+
+  if (is_empty()) {
+    return NULL;
+  }
+  assert(length() > 0 && _head != NULL && _tail != NULL,
+         hrs_ext_msg(this, "invariant"));
+
+  HeapRegion* hr;
+
+  if (from_head) {
+    hr = remove_from_head_impl();
+  } else {
+    hr = remove_from_tail_impl();
+  }
 
   if (_last == hr) {
     _last = NULL;
@@ -154,56 +148,5 @@
   return hr;
 }
 
-inline HeapRegion* FreeRegionList::remove_head_or_null() {
-  check_mt_safety();
-  if (!is_empty()) {
-    return remove_head();
-  } else {
-    return NULL;
-  }
-}
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP
 
-inline HeapRegion* FreeRegionList::remove_tail() {
-  assert(!is_empty(), hrs_ext_msg(this, "The list should not be empty"));
-  assert(length() > 0 && _head != NULL && _tail != NULL,
-         hrs_ext_msg(this, "invariant"));
-
-  // We need to unlink it first
-  HeapRegion* hr = _tail;
-
-  _tail = hr->prev();
-  if (_tail == NULL) {
-    _head = NULL;
-  } else {
-    _tail->set_next(NULL);
-  }
-  hr->set_prev(NULL);
-
-  if (_last == hr) {
-    _last = NULL;
-  }
-
-  // remove() will verify the region and check mt safety.
-  remove(hr);
-  return hr;
-}
-
-inline HeapRegion* FreeRegionList::remove_tail_or_null() {
-  check_mt_safety();
-
-  if (!is_empty()) {
-    return remove_tail();
-  } else {
-    return NULL;
-  }
-}
-
-inline HeapRegion* FreeRegionList::remove_region(bool from_head) {
-  if (from_head) {
-    return remove_head_or_null();
-  } else {
-    return remove_tail_or_null();
-  }
-}
-
-#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_INLINE_HPP
--- a/hotspot/src/share/vm/gc_implementation/g1/vmStructs_g1.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/vmStructs_g1.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -43,10 +43,9 @@
   nonstatic_field(G1HeapRegionTable, _shift_by,         uint)                 \
                                                                               \
   nonstatic_field(HeapRegionSeq,   _regions,            G1HeapRegionTable)    \
-  nonstatic_field(HeapRegionSeq,   _committed_length,   uint)                 \
+  nonstatic_field(HeapRegionSeq,   _num_committed,      uint)                 \
                                                                               \
   nonstatic_field(G1CollectedHeap, _hrs,                HeapRegionSeq)        \
-  nonstatic_field(G1CollectedHeap, _g1_committed,       MemRegion)            \
   nonstatic_field(G1CollectedHeap, _summary_bytes_used, size_t)               \
   nonstatic_field(G1CollectedHeap, _g1mm,               G1MonitoringSupport*) \
   nonstatic_field(G1CollectedHeap, _old_set,            HeapRegionSetBase)    \
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -78,6 +78,7 @@
                         (HeapWord*)(heap_rs.base() + heap_rs.size()));
 
   CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3);
+  barrier_set->initialize();
   _barrier_set = barrier_set;
   oopDesc::set_bs(_barrier_set);
   if (_barrier_set == NULL) {
--- a/hotspot/src/share/vm/memory/cardTableModRefBS.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/memory/cardTableModRefBS.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -44,13 +44,6 @@
 // enumerate ref fields that have been modified (since the last
 // enumeration.)
 
-size_t CardTableModRefBS::cards_required(size_t covered_words)
-{
-  // Add one for a guard card, used to detect errors.
-  const size_t words = align_size_up(covered_words, card_size_in_words);
-  return words / card_size_in_words + 1;
-}
-
 size_t CardTableModRefBS::compute_byte_map_size()
 {
   assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,
@@ -64,27 +57,50 @@
                                      int max_covered_regions):
   ModRefBarrierSet(max_covered_regions),
   _whole_heap(whole_heap),
-  _guard_index(cards_required(whole_heap.word_size()) - 1),
-  _last_valid_index(_guard_index - 1),
+  _guard_index(0),
+  _guard_region(),
+  _last_valid_index(0),
   _page_size(os::vm_page_size()),
-  _byte_map_size(compute_byte_map_size())
+  _byte_map_size(0),
+  _covered(NULL),
+  _committed(NULL),
+  _cur_covered_regions(0),
+  _byte_map(NULL),
+  byte_map_base(NULL),
+  // LNC functionality
+  _lowest_non_clean(NULL),
+  _lowest_non_clean_chunk_size(NULL),
+  _lowest_non_clean_base_chunk_index(NULL),
+  _last_LNC_resizing_collection(NULL)
 {
   _kind = BarrierSet::CardTableModRef;
 
-  HeapWord* low_bound  = _whole_heap.start();
-  HeapWord* high_bound = _whole_heap.end();
-  assert((uintptr_t(low_bound)  & (card_size - 1))  == 0, "heap must start at card boundary");
-  assert((uintptr_t(high_bound) & (card_size - 1))  == 0, "heap must end at card boundary");
+  assert((uintptr_t(_whole_heap.start())  & (card_size - 1))  == 0, "heap must start at card boundary");
+  assert((uintptr_t(_whole_heap.end()) & (card_size - 1))  == 0, "heap must end at card boundary");
 
   assert(card_size <= 512, "card_size must be less than 512"); // why?
 
-  _covered   = new MemRegion[max_covered_regions];
-  _committed = new MemRegion[max_covered_regions];
-  if (_covered == NULL || _committed == NULL) {
-    vm_exit_during_initialization("couldn't alloc card table covered region set.");
+  _covered   = new MemRegion[_max_covered_regions];
+  if (_covered == NULL) {
+    vm_exit_during_initialization("Could not allocate card table covered region set.");
+  }
+}
+
+void CardTableModRefBS::initialize() {
+  _guard_index = cards_required(_whole_heap.word_size()) - 1;
+  _last_valid_index = _guard_index - 1;
+
+  _byte_map_size = compute_byte_map_size();
+
+  HeapWord* low_bound  = _whole_heap.start();
+  HeapWord* high_bound = _whole_heap.end();
+
+  _cur_covered_regions = 0;
+  _committed = new MemRegion[_max_covered_regions];
+  if (_committed == NULL) {
+    vm_exit_during_initialization("Could not allocate card table committed region set.");
   }
 
-  _cur_covered_regions = 0;
   const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :
     MAX2(_page_size, (size_t) os::vm_allocation_granularity());
   ReservedSpace heap_rs(_byte_map_size, rs_align, false);
@@ -114,20 +130,20 @@
                             !ExecMem, "card table last card");
   *guard_card = last_card;
 
-   _lowest_non_clean =
-    NEW_C_HEAP_ARRAY(CardArr, max_covered_regions, mtGC);
+  _lowest_non_clean =
+    NEW_C_HEAP_ARRAY(CardArr, _max_covered_regions, mtGC);
   _lowest_non_clean_chunk_size =
-    NEW_C_HEAP_ARRAY(size_t, max_covered_regions, mtGC);
+    NEW_C_HEAP_ARRAY(size_t, _max_covered_regions, mtGC);
   _lowest_non_clean_base_chunk_index =
-    NEW_C_HEAP_ARRAY(uintptr_t, max_covered_regions, mtGC);
+    NEW_C_HEAP_ARRAY(uintptr_t, _max_covered_regions, mtGC);
   _last_LNC_resizing_collection =
-    NEW_C_HEAP_ARRAY(int, max_covered_regions, mtGC);
+    NEW_C_HEAP_ARRAY(int, _max_covered_regions, mtGC);
   if (_lowest_non_clean == NULL
       || _lowest_non_clean_chunk_size == NULL
       || _lowest_non_clean_base_chunk_index == NULL
       || _last_LNC_resizing_collection == NULL)
     vm_exit_during_initialization("couldn't allocate an LNC array.");
-  for (int i = 0; i < max_covered_regions; i++) {
+  for (int i = 0; i < _max_covered_regions; i++) {
     _lowest_non_clean[i] = NULL;
     _lowest_non_clean_chunk_size[i] = 0;
     _last_LNC_resizing_collection[i] = -1;
@@ -650,7 +666,7 @@
                                       jbyte val, bool val_equals) {
   jbyte* start    = byte_for(mr.start());
   jbyte* end      = byte_for(mr.last());
-  bool   failures = false;
+  bool failures = false;
   for (jbyte* curr = start; curr <= end; ++curr) {
     jbyte curr_val = *curr;
     bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);
--- a/hotspot/src/share/vm/memory/cardTableModRefBS.hpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/memory/cardTableModRefBS.hpp	Tue Aug 19 13:44:55 2014 -0700
@@ -96,12 +96,12 @@
   // The declaration order of these const fields is important; see the
   // constructor before changing.
   const MemRegion _whole_heap;       // the region covered by the card table
-  const size_t    _guard_index;      // index of very last element in the card
+  size_t          _guard_index;      // index of very last element in the card
                                      // table; it is set to a guard value
                                      // (last_card) and should never be modified
-  const size_t    _last_valid_index; // index of the last valid element
+  size_t          _last_valid_index; // index of the last valid element
   const size_t    _page_size;        // page size used when mapping _byte_map
-  const size_t    _byte_map_size;    // in bytes
+  size_t          _byte_map_size;    // in bytes
   jbyte*          _byte_map;         // the card marking array
 
   int _cur_covered_regions;
@@ -123,7 +123,12 @@
  protected:
   // Initialization utilities; covered_words is the size of the covered region
   // in, um, words.
-  inline size_t cards_required(size_t covered_words);
+  inline size_t cards_required(size_t covered_words) {
+    // Add one for a guard card, used to detect errors.
+    const size_t words = align_size_up(covered_words, card_size_in_words);
+    return words / card_size_in_words + 1;
+  }
+
   inline size_t compute_byte_map_size();
 
   // Finds and return the index of the region, if any, to which the given
@@ -137,7 +142,7 @@
   int find_covering_region_containing(HeapWord* addr);
 
   // Resize one of the regions covered by the remembered set.
-  void resize_covered_region(MemRegion new_region);
+  virtual void resize_covered_region(MemRegion new_region);
 
   // Returns the leftmost end of a committed region corresponding to a
   // covered region before covered region "ind", or else "NULL" if "ind" is
@@ -282,6 +287,8 @@
   CardTableModRefBS(MemRegion whole_heap, int max_covered_regions);
   ~CardTableModRefBS();
 
+  virtual void initialize();
+
   // *** Barrier set functions.
 
   bool has_write_ref_pre_barrier() { return false; }
--- a/hotspot/src/share/vm/memory/cardTableRS.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/memory/cardTableRS.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -54,6 +54,7 @@
 #else
   _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
 #endif
+  _ct_bs->initialize();
   set_bs(_ct_bs);
   _last_cur_val_in_gen = NEW_C_HEAP_ARRAY3(jbyte, GenCollectedHeap::max_gens + 1,
                          mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
--- a/hotspot/src/share/vm/prims/jni.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/prims/jni.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -3865,6 +3865,7 @@
 void TestG1BiasedArray_test();
 void TestBufferingOopClosure_test();
 void TestCodeCacheRemSet_test();
+void FreeRegionList_test();
 #endif
 
 void execute_internal_vm_tests() {
@@ -3900,6 +3901,9 @@
     run_unit_test(HeapRegionRemSet::test_prt());
     run_unit_test(TestBufferingOopClosure_test());
     run_unit_test(TestCodeCacheRemSet_test());
+    if (UseG1GC) {
+      run_unit_test(FreeRegionList_test());
+    }
 #endif
     tty->print_cr("All internal VM tests passed");
   }
--- a/hotspot/src/share/vm/prims/whitebox.cpp	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/src/share/vm/prims/whitebox.cpp	Tue Aug 19 13:44:55 2014 -0700
@@ -237,7 +237,7 @@
 
 WB_ENTRY(jlong, WB_G1NumFreeRegions(JNIEnv* env, jobject o))
   G1CollectedHeap* g1 = G1CollectedHeap::heap();
-  size_t nr = g1->free_regions();
+  size_t nr = g1->num_free_regions();
   return (jlong)nr;
 WB_END
 
--- a/hotspot/test/gc/class_unloading/TestCMSClassUnloadingEnabledHWM.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/test/gc/class_unloading/TestCMSClassUnloadingEnabledHWM.java	Tue Aug 19 13:44:55 2014 -0700
@@ -46,6 +46,7 @@
   private static OutputAnalyzer run(boolean enableUnloading) throws Exception {
     ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
       "-Xbootclasspath/a:.",
+      "-XX:+UnlockDiagnosticVMOptions",
       "-XX:+WhiteBoxAPI",
       "-XX:MetaspaceSize=" + MetaspaceSize,
       "-Xmn" + YoungGenSize,
--- a/hotspot/test/gc/class_unloading/TestG1ClassUnloadingHWM.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/test/gc/class_unloading/TestG1ClassUnloadingHWM.java	Tue Aug 19 13:44:55 2014 -0700
@@ -46,6 +46,7 @@
   private static OutputAnalyzer run(boolean enableUnloading) throws Exception {
     ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
       "-Xbootclasspath/a:.",
+      "-XX:+UnlockDiagnosticVMOptions",
       "-XX:+WhiteBoxAPI",
       "-XX:MetaspaceSize=" + MetaspaceSize,
       "-Xmn" + YoungGenSize,
--- a/hotspot/test/gc/g1/TestEagerReclaimHumongousRegions2.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/test/gc/g1/TestEagerReclaimHumongousRegions2.java	Tue Aug 19 13:44:55 2014 -0700
@@ -46,6 +46,8 @@
 }
 
 class ReclaimRegionFast {
+    public static final long MAX_MILLIS_FOR_RUN = 50 * 1000; // The maximum runtime for the actual test.
+
     public static final int M = 1024*1024;
 
     public static LinkedList<Object> garbageList = new LinkedList<Object>();
@@ -83,7 +85,14 @@
 
         Object ref_from_stack = large1;
 
+        long start_millis = System.currentTimeMillis();
+
         for (int i = 0; i < 20; i++) {
+            long current_millis = System.currentTimeMillis();
+            if ((current_millis - start_millis) > MAX_MILLIS_FOR_RUN) {
+              System.out.println("Finishing test because maximum runtime exceeded");
+              break;
+            }
             // A set of large objects that will be reclaimed eagerly - and hopefully marked.
             large1 = new int[M - 20];
             large2 = new int[M - 20];
--- a/hotspot/test/sanity/WhiteBox.java	Fri Aug 15 09:19:22 2014 -0700
+++ b/hotspot/test/sanity/WhiteBox.java	Tue Aug 19 13:44:55 2014 -0700
@@ -29,7 +29,6 @@
  * @library /testlibrary
  * @compile WhiteBox.java
  * @run main ClassFileInstaller sun.hotspot.WhiteBox
- *                              sun.hotspot.WhiteBox$WhiteBoxPermission
  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI sun.hotspot.WhiteBox
  * @clean sun.hotspot.WhiteBox
  */