# HG changeset patch
# User jcoomes
# Date 1222802422 25200
# Node ID 9006b01ba3fd8f22f300ffc3f353da147b4584df
# Parent  e5e2b519fc11c71e49ba959889419e8df18e15a4
6725697: par compact - rename class ChunkData to RegionData
Reviewed-by: iveresov, tonyp

diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp	Tue Sep 30 12:20:22 2008 -0700
@@ -146,7 +146,7 @@
 {
   ParallelScavengeHeap* heap = PSParallelCompact::gc_heap();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
-  ChunkTaskQueueSet* qset = ParCompactionManager::chunk_array();
+  RegionTaskQueueSet* qset = ParCompactionManager::region_array();
   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
   GCTaskQueue* q = GCTaskQueue::create();
   for(uint i=0; i<parallel_gc_threads; i++) {
@@ -205,38 +205,38 @@
 }
 
 //
-// StealChunkCompactionTask
+// StealRegionCompactionTask
 //
 
 
-StealChunkCompactionTask::StealChunkCompactionTask(ParallelTaskTerminator* t) :
-  _terminator(t) {};
+StealRegionCompactionTask::StealRegionCompactionTask(ParallelTaskTerminator* t):
+  _terminator(t) {}
 
-void StealChunkCompactionTask::do_it(GCTaskManager* manager, uint which) {
+void StealRegionCompactionTask::do_it(GCTaskManager* manager, uint which) {
   assert(Universe::heap()->is_gc_active(), "called outside gc");
 
-  NOT_PRODUCT(TraceTime tm("StealChunkCompactionTask",
+  NOT_PRODUCT(TraceTime tm("StealRegionCompactionTask",
     PrintGCDetails && TraceParallelOldGCTasks, true, gclog_or_tty));
 
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
 
-  // Has to drain stacks first because there may be chunks on
+  // Has to drain stacks first because there may be regions on
   // preloaded onto the stack and this thread may never have
   // done a draining task.  Are the draining tasks needed?
 
-  cm->drain_chunk_stacks();
+  cm->drain_region_stacks();
 
-  size_t chunk_index = 0;
+  size_t region_index = 0;
   int random_seed = 17;
 
   // If we're the termination task, try 10 rounds of stealing before
   // setting the termination flag
 
   while(true) {
-    if (ParCompactionManager::steal(which, &random_seed, chunk_index)) {
-      PSParallelCompact::fill_and_update_chunk(cm, chunk_index);
-      cm->drain_chunk_stacks();
+    if (ParCompactionManager::steal(which, &random_seed, region_index)) {
+      PSParallelCompact::fill_and_update_region(cm, region_index);
+      cm->drain_region_stacks();
     } else {
       if (terminator()->offer_termination()) {
         break;
@@ -249,11 +249,10 @@
 
 UpdateDensePrefixTask::UpdateDensePrefixTask(
                                    PSParallelCompact::SpaceId space_id,
-                                   size_t chunk_index_start,
-                                   size_t chunk_index_end) :
-  _space_id(space_id), _chunk_index_start(chunk_index_start),
-  _chunk_index_end(chunk_index_end)
-{}
+                                   size_t region_index_start,
+                                   size_t region_index_end) :
+  _space_id(space_id), _region_index_start(region_index_start),
+  _region_index_end(region_index_end) {}
 
 void UpdateDensePrefixTask::do_it(GCTaskManager* manager, uint which) {
 
@@ -265,8 +264,8 @@
 
   PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
                                                          _space_id,
-                                                         _chunk_index_start,
-                                                         _chunk_index_end);
+                                                         _region_index_start,
+                                                         _region_index_end);
 }
 
 void DrainStacksCompactionTask::do_it(GCTaskManager* manager, uint which) {
@@ -278,6 +277,6 @@
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
 
-  // Process any chunks already in the compaction managers stacks.
-  cm->drain_chunk_stacks();
+  // Process any regions already in the compaction managers stacks.
+  cm->drain_region_stacks();
 }
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.hpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.hpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.hpp	Tue Sep 30 12:20:22 2008 -0700
@@ -188,18 +188,18 @@
 };
 
 //
-// StealChunkCompactionTask
+// StealRegionCompactionTask
 //
 // This task is used to distribute work to idle threads.
 //
 
-class StealChunkCompactionTask : public GCTask {
+class StealRegionCompactionTask : public GCTask {
  private:
    ParallelTaskTerminator* const _terminator;
  public:
-  StealChunkCompactionTask(ParallelTaskTerminator* t);
+  StealRegionCompactionTask(ParallelTaskTerminator* t);
 
-  char* name() { return (char *)"steal-chunk-task"; }
+  char* name() { return (char *)"steal-region-task"; }
   ParallelTaskTerminator* terminator() { return _terminator; }
 
   virtual void do_it(GCTaskManager* manager, uint which);
@@ -215,15 +215,15 @@
 class UpdateDensePrefixTask : public GCTask {
  private:
   PSParallelCompact::SpaceId _space_id;
-  size_t _chunk_index_start;
-  size_t _chunk_index_end;
+  size_t _region_index_start;
+  size_t _region_index_end;
 
  public:
   char* name() { return (char *)"update-dense_prefix-task"; }
 
   UpdateDensePrefixTask(PSParallelCompact::SpaceId space_id,
-                        size_t chunk_index_start,
-                        size_t chunk_index_end);
+                        size_t region_index_start,
+                        size_t region_index_end);
 
   virtual void do_it(GCTaskManager* manager, uint which);
 };
@@ -231,17 +231,17 @@
 //
 // DrainStacksCompactionTask
 //
-// This task processes chunks that have been added to the stacks of each
+// This task processes regions that have been added to the stacks of each
 // compaction manager.
 //
 // Trying to use one draining thread does not work because there are no
 // guarantees about which task will be picked up by which thread.  For example,
-// if thread A gets all the preloaded chunks, thread A may not get a draining
+// if thread A gets all the preloaded regions, thread A may not get a draining
 // task (they may all be done by other threads).
 //
 
 class DrainStacksCompactionTask : public GCTask {
  public:
-  char* name() { return (char *)"drain-chunk-task"; }
+  char* name() { return (char *)"drain-region-task"; }
   virtual void do_it(GCTaskManager* manager, uint which);
 };
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.cpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.cpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.cpp	Tue Sep 30 12:20:22 2008 -0700
@@ -30,7 +30,7 @@
 OopTaskQueueSet*     ParCompactionManager::_stack_array = NULL;
 ObjectStartArray*    ParCompactionManager::_start_array = NULL;
 ParMarkBitMap*       ParCompactionManager::_mark_bitmap = NULL;
-ChunkTaskQueueSet*   ParCompactionManager::_chunk_array = NULL;
+RegionTaskQueueSet*   ParCompactionManager::_region_array = NULL;
 
 ParCompactionManager::ParCompactionManager() :
     _action(CopyAndUpdate) {
@@ -46,13 +46,13 @@
 
   // We want the overflow stack to be permanent
   _overflow_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(10, true);
-#ifdef USE_ChunkTaskQueueWithOverflow
-  chunk_stack()->initialize();
+#ifdef USE_RegionTaskQueueWithOverflow
+  region_stack()->initialize();
 #else
-  chunk_stack()->initialize();
+  region_stack()->initialize();
 
   // We want the overflow stack to be permanent
-  _chunk_overflow_stack =
+  _region_overflow_stack =
     new (ResourceObj::C_HEAP) GrowableArray<size_t>(10, true);
 #endif
 
@@ -86,18 +86,18 @@
 
   _stack_array = new OopTaskQueueSet(parallel_gc_threads);
   guarantee(_stack_array != NULL, "Count not initialize promotion manager");
-  _chunk_array = new ChunkTaskQueueSet(parallel_gc_threads);
-  guarantee(_chunk_array != NULL, "Count not initialize promotion manager");
+  _region_array = new RegionTaskQueueSet(parallel_gc_threads);
+  guarantee(_region_array != NULL, "Count not initialize promotion manager");
 
   // Create and register the ParCompactionManager(s) for the worker threads.
   for(uint i=0; i<parallel_gc_threads; i++) {
     _manager_array[i] = new ParCompactionManager();
     guarantee(_manager_array[i] != NULL, "Could not create ParCompactionManager");
     stack_array()->register_queue(i, _manager_array[i]->marking_stack());
-#ifdef USE_ChunkTaskQueueWithOverflow
-    chunk_array()->register_queue(i, _manager_array[i]->chunk_stack()->task_queue());
+#ifdef USE_RegionTaskQueueWithOverflow
+    region_array()->register_queue(i, _manager_array[i]->region_stack()->task_queue());
 #else
-    chunk_array()->register_queue(i, _manager_array[i]->chunk_stack());
+    region_array()->register_queue(i, _manager_array[i]->region_stack());
 #endif
   }
 
@@ -153,31 +153,31 @@
   return NULL;
 }
 
-// Save chunk on a stack
-void ParCompactionManager::save_for_processing(size_t chunk_index) {
+// Save region on a stack
+void ParCompactionManager::save_for_processing(size_t region_index) {
 #ifdef ASSERT
   const ParallelCompactData& sd = PSParallelCompact::summary_data();
-  ParallelCompactData::ChunkData* const chunk_ptr = sd.chunk(chunk_index);
-  assert(chunk_ptr->claimed(), "must be claimed");
-  assert(chunk_ptr->_pushed++ == 0, "should only be pushed once");
+  ParallelCompactData::RegionData* const region_ptr = sd.region(region_index);
+  assert(region_ptr->claimed(), "must be claimed");
+  assert(region_ptr->_pushed++ == 0, "should only be pushed once");
 #endif
-  chunk_stack_push(chunk_index);
+  region_stack_push(region_index);
 }
 
-void ParCompactionManager::chunk_stack_push(size_t chunk_index) {
+void ParCompactionManager::region_stack_push(size_t region_index) {
 
-#ifdef USE_ChunkTaskQueueWithOverflow
-  chunk_stack()->save(chunk_index);
+#ifdef USE_RegionTaskQueueWithOverflow
+  region_stack()->save(region_index);
 #else
-  if(!chunk_stack()->push(chunk_index)) {
-    chunk_overflow_stack()->push(chunk_index);
+  if(!region_stack()->push(region_index)) {
+    region_overflow_stack()->push(region_index);
   }
 #endif
 }
 
-bool ParCompactionManager::retrieve_for_processing(size_t& chunk_index) {
-#ifdef USE_ChunkTaskQueueWithOverflow
-  return chunk_stack()->retrieve(chunk_index);
+bool ParCompactionManager::retrieve_for_processing(size_t& region_index) {
+#ifdef USE_RegionTaskQueueWithOverflow
+  return region_stack()->retrieve(region_index);
 #else
   // Should not be used in the parallel case
   ShouldNotReachHere();
@@ -230,14 +230,14 @@
   assert(overflow_stack()->length() == 0, "Sanity");
 }
 
-void ParCompactionManager::drain_chunk_overflow_stack() {
-  size_t chunk_index = (size_t) -1;
-  while(chunk_stack()->retrieve_from_overflow(chunk_index)) {
-    PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+void ParCompactionManager::drain_region_overflow_stack() {
+  size_t region_index = (size_t) -1;
+  while(region_stack()->retrieve_from_overflow(region_index)) {
+    PSParallelCompact::fill_and_update_region(this, region_index);
   }
 }
 
-void ParCompactionManager::drain_chunk_stacks() {
+void ParCompactionManager::drain_region_stacks() {
 #ifdef ASSERT
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
@@ -249,42 +249,42 @@
 #if 1 // def DO_PARALLEL - the serial code hasn't been updated
   do {
 
-#ifdef USE_ChunkTaskQueueWithOverflow
+#ifdef USE_RegionTaskQueueWithOverflow
     // Drain overflow stack first, so other threads can steal from
     // claimed stack while we work.
-    size_t chunk_index = (size_t) -1;
-    while(chunk_stack()->retrieve_from_overflow(chunk_index)) {
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+    size_t region_index = (size_t) -1;
+    while(region_stack()->retrieve_from_overflow(region_index)) {
+      PSParallelCompact::fill_and_update_region(this, region_index);
     }
 
-    while (chunk_stack()->retrieve_from_stealable_queue(chunk_index)) {
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+    while (region_stack()->retrieve_from_stealable_queue(region_index)) {
+      PSParallelCompact::fill_and_update_region(this, region_index);
     }
-  } while (!chunk_stack()->is_empty());
+  } while (!region_stack()->is_empty());
 #else
     // Drain overflow stack first, so other threads can steal from
     // claimed stack while we work.
-    while(!chunk_overflow_stack()->is_empty()) {
-      size_t chunk_index = chunk_overflow_stack()->pop();
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+    while(!region_overflow_stack()->is_empty()) {
+      size_t region_index = region_overflow_stack()->pop();
+      PSParallelCompact::fill_and_update_region(this, region_index);
     }
 
-    size_t chunk_index = -1;
+    size_t region_index = -1;
     // obj is a reference!!!
-    while (chunk_stack()->pop_local(chunk_index)) {
+    while (region_stack()->pop_local(region_index)) {
       // It would be nice to assert about the type of objects we might
       // pop, but they can come from anywhere, unfortunately.
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+      PSParallelCompact::fill_and_update_region(this, region_index);
     }
-  } while((chunk_stack()->size() != 0) ||
-          (chunk_overflow_stack()->length() != 0));
+  } while((region_stack()->size() != 0) ||
+          (region_overflow_stack()->length() != 0));
 #endif
 
-#ifdef USE_ChunkTaskQueueWithOverflow
-  assert(chunk_stack()->is_empty(), "Sanity");
+#ifdef USE_RegionTaskQueueWithOverflow
+  assert(region_stack()->is_empty(), "Sanity");
 #else
-  assert(chunk_stack()->size() == 0, "Sanity");
-  assert(chunk_overflow_stack()->length() == 0, "Sanity");
+  assert(region_stack()->size() == 0, "Sanity");
+  assert(region_overflow_stack()->length() == 0, "Sanity");
 #endif
 #else
   oop obj;
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.hpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.hpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.hpp	Tue Sep 30 12:20:22 2008 -0700
@@ -52,7 +52,7 @@
   friend class ParallelTaskTerminator;
   friend class ParMarkBitMap;
   friend class PSParallelCompact;
-  friend class StealChunkCompactionTask;
+  friend class StealRegionCompactionTask;
   friend class UpdateAndFillClosure;
   friend class RefProcTaskExecutor;
 
@@ -72,27 +72,27 @@
 // ------------------------  End don't putback if not needed
 
  private:
-  static ParCompactionManager**  _manager_array;
-  static OopTaskQueueSet*      _stack_array;
-  static ObjectStartArray*     _start_array;
-  static ChunkTaskQueueSet*    _chunk_array;
-  static PSOldGen*             _old_gen;
+  static ParCompactionManager** _manager_array;
+  static OopTaskQueueSet*       _stack_array;
+  static ObjectStartArray*      _start_array;
+  static RegionTaskQueueSet*    _region_array;
+  static PSOldGen*              _old_gen;
 
-  OopTaskQueue                 _marking_stack;
-  GrowableArray<oop>*          _overflow_stack;
+  OopTaskQueue                  _marking_stack;
+  GrowableArray<oop>*           _overflow_stack;
   // Is there a way to reuse the _marking_stack for the
-  // saving empty chunks?  For now just create a different
+  // saving empty regions?  For now just create a different
   // type of TaskQueue.
 
-#ifdef USE_ChunkTaskQueueWithOverflow
-  ChunkTaskQueueWithOverflow   _chunk_stack;
+#ifdef USE_RegionTaskQueueWithOverflow
+  RegionTaskQueueWithOverflow   _region_stack;
 #else
-  ChunkTaskQueue               _chunk_stack;
-  GrowableArray<size_t>*       _chunk_overflow_stack;
+  RegionTaskQueue               _region_stack;
+  GrowableArray<size_t>*        _region_overflow_stack;
 #endif
 
 #if 1  // does this happen enough to need a per thread stack?
-  GrowableArray<Klass*>*       _revisit_klass_stack;
+  GrowableArray<Klass*>*        _revisit_klass_stack;
 #endif
   static ParMarkBitMap* _mark_bitmap;
 
@@ -100,21 +100,22 @@
 
   static PSOldGen* old_gen()             { return _old_gen; }
   static ObjectStartArray* start_array() { return _start_array; }
-  static OopTaskQueueSet* stack_array()   { return _stack_array; }
+  static OopTaskQueueSet* stack_array()  { return _stack_array; }
 
   static void initialize(ParMarkBitMap* mbm);
 
  protected:
   // Array of tasks.  Needed by the ParallelTaskTerminator.
-  static ChunkTaskQueueSet* chunk_array()   { return _chunk_array; }
-
-  OopTaskQueue*  marking_stack()          { return &_marking_stack; }
-  GrowableArray<oop>* overflow_stack()    { return _overflow_stack; }
-#ifdef USE_ChunkTaskQueueWithOverflow
-  ChunkTaskQueueWithOverflow* chunk_stack() { return &_chunk_stack; }
+  static RegionTaskQueueSet* region_array()      { return _region_array; }
+  OopTaskQueue*  marking_stack()                 { return &_marking_stack; }
+  GrowableArray<oop>* overflow_stack()           { return _overflow_stack; }
+#ifdef USE_RegionTaskQueueWithOverflow
+  RegionTaskQueueWithOverflow* region_stack()    { return &_region_stack; }
 #else
-  ChunkTaskQueue*  chunk_stack()          { return &_chunk_stack; }
-  GrowableArray<size_t>* chunk_overflow_stack() { return _chunk_overflow_stack; }
+  RegionTaskQueue*  region_stack()               { return &_region_stack; }
+  GrowableArray<size_t>* region_overflow_stack() {
+    return _region_overflow_stack;
+  }
 #endif
 
   // Pushes onto the marking stack.  If the marking stack is full,
@@ -123,9 +124,9 @@
   // Do not implement an equivalent stack_pop.  Deal with the
   // marking stack and overflow stack directly.
 
-  // Pushes onto the chunk stack.  If the chunk stack is full,
-  // pushes onto the chunk overflow stack.
-  void chunk_stack_push(size_t chunk_index);
+  // Pushes onto the region stack.  If the region stack is full,
+  // pushes onto the region overflow stack.
+  void region_stack_push(size_t region_index);
  public:
 
   Action action() { return _action; }
@@ -160,10 +161,10 @@
   // Get a oop for scanning.  If returns null, no oop were found.
   oop retrieve_for_scanning();
 
-  // Save chunk for later processing.  Must not fail.
-  void save_for_processing(size_t chunk_index);
-  // Get a chunk for processing.  If returns null, no chunk were found.
-  bool retrieve_for_processing(size_t& chunk_index);
+  // Save region for later processing.  Must not fail.
+  void save_for_processing(size_t region_index);
+  // Get a region for processing.  If returns null, no region were found.
+  bool retrieve_for_processing(size_t& region_index);
 
   // Access function for compaction managers
   static ParCompactionManager* gc_thread_compaction_manager(int index);
@@ -172,18 +173,18 @@
     return stack_array()->steal(queue_num, seed, t);
   }
 
-  static bool steal(int queue_num, int* seed, ChunkTask& t) {
-    return chunk_array()->steal(queue_num, seed, t);
+  static bool steal(int queue_num, int* seed, RegionTask& t) {
+    return region_array()->steal(queue_num, seed, t);
   }
 
   // Process tasks remaining on any stack
   void drain_marking_stacks(OopClosure *blk);
 
   // Process tasks remaining on any stack
-  void drain_chunk_stacks();
+  void drain_region_stacks();
 
   // Process tasks remaining on any stack
-  void drain_chunk_overflow_stack();
+  void drain_region_overflow_stack();
 
   // Debugging support
 #ifdef ASSERT
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	Tue Sep 30 12:20:22 2008 -0700
@@ -28,12 +28,13 @@
 #include <math.h>
 
 // All sizes are in HeapWords.
-const size_t ParallelCompactData::Log2ChunkSize  = 9; // 512 words
-const size_t ParallelCompactData::ChunkSize      = (size_t)1 << Log2ChunkSize;
-const size_t ParallelCompactData::ChunkSizeBytes = ChunkSize << LogHeapWordSize;
-const size_t ParallelCompactData::ChunkSizeOffsetMask = ChunkSize - 1;
-const size_t ParallelCompactData::ChunkAddrOffsetMask = ChunkSizeBytes - 1;
-const size_t ParallelCompactData::ChunkAddrMask  = ~ChunkAddrOffsetMask;
+const size_t ParallelCompactData::Log2RegionSize  = 9; // 512 words
+const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
+const size_t ParallelCompactData::RegionSizeBytes =
+  RegionSize << LogHeapWordSize;
+const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
+const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
+const size_t ParallelCompactData::RegionAddrMask  = ~RegionAddrOffsetMask;
 
 // 32-bit:  128 words covers 4 bitmap words
 // 64-bit:  128 words covers 2 bitmap words
@@ -42,25 +43,25 @@
 const size_t ParallelCompactData::BlockOffsetMask = BlockSize - 1;
 const size_t ParallelCompactData::BlockMask       = ~BlockOffsetMask;
 
-const size_t ParallelCompactData::BlocksPerChunk = ChunkSize / BlockSize;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::dc_shift = 27;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::dc_mask = ~0U << dc_shift;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::dc_one = 0x1U << dc_shift;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::los_mask = ~dc_mask;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::dc_claimed = 0x8U << dc_shift;
-
-const ParallelCompactData::ChunkData::chunk_sz_t
-ParallelCompactData::ChunkData::dc_completed = 0xcU << dc_shift;
+const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_shift = 27;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::los_mask = ~dc_mask;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
+
+const ParallelCompactData::RegionData::region_sz_t
+ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
 
 #ifdef ASSERT
 short   ParallelCompactData::BlockData::_cur_phase = 0;
@@ -105,7 +106,7 @@
   "perm", "old ", "eden", "from", "to  "
 };
 
-void PSParallelCompact::print_chunk_ranges()
+void PSParallelCompact::print_region_ranges()
 {
   tty->print_cr("space  bottom     top        end        new_top");
   tty->print_cr("------ ---------- ---------- ---------- ----------");
@@ -116,31 +117,31 @@
                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
                   id, space_names[id],
-                  summary_data().addr_to_chunk_idx(space->bottom()),
-                  summary_data().addr_to_chunk_idx(space->top()),
-                  summary_data().addr_to_chunk_idx(space->end()),
-                  summary_data().addr_to_chunk_idx(_space_info[id].new_top()));
+                  summary_data().addr_to_region_idx(space->bottom()),
+                  summary_data().addr_to_region_idx(space->top()),
+                  summary_data().addr_to_region_idx(space->end()),
+                  summary_data().addr_to_region_idx(_space_info[id].new_top()));
   }
 }
 
 void
-print_generic_summary_chunk(size_t i, const ParallelCompactData::ChunkData* c)
+print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 {
-#define CHUNK_IDX_FORMAT        SIZE_FORMAT_W(7)
-#define CHUNK_DATA_FORMAT       SIZE_FORMAT_W(5)
+#define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
+#define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 
   ParallelCompactData& sd = PSParallelCompact::summary_data();
-  size_t dci = c->destination() ? sd.addr_to_chunk_idx(c->destination()) : 0;
-  tty->print_cr(CHUNK_IDX_FORMAT " " PTR_FORMAT " "
-                CHUNK_IDX_FORMAT " " PTR_FORMAT " "
-                CHUNK_DATA_FORMAT " " CHUNK_DATA_FORMAT " "
-                CHUNK_DATA_FORMAT " " CHUNK_IDX_FORMAT " %d",
+  size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
+  tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
+                REGION_IDX_FORMAT " " PTR_FORMAT " "
+                REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
+                REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
                 i, c->data_location(), dci, c->destination(),
                 c->partial_obj_size(), c->live_obj_size(),
-                c->data_size(), c->source_chunk(), c->destination_count());
-
-#undef  CHUNK_IDX_FORMAT
-#undef  CHUNK_DATA_FORMAT
+                c->data_size(), c->source_region(), c->destination_count());
+
+#undef  REGION_IDX_FORMAT
+#undef  REGION_DATA_FORMAT
 }
 
 void
@@ -149,14 +150,14 @@
                            HeapWord* const end_addr)
 {
   size_t total_words = 0;
-  size_t i = summary_data.addr_to_chunk_idx(beg_addr);
-  const size_t last = summary_data.addr_to_chunk_idx(end_addr);
+  size_t i = summary_data.addr_to_region_idx(beg_addr);
+  const size_t last = summary_data.addr_to_region_idx(end_addr);
   HeapWord* pdest = 0;
 
   while (i <= last) {
-    ParallelCompactData::ChunkData* c = summary_data.chunk(i);
+    ParallelCompactData::RegionData* c = summary_data.region(i);
     if (c->data_size() != 0 || c->destination() != pdest) {
-      print_generic_summary_chunk(i, c);
+      print_generic_summary_region(i, c);
       total_words += c->data_size();
       pdest = c->destination();
     }
@@ -178,16 +179,16 @@
 }
 
 void
-print_initial_summary_chunk(size_t i,
-                            const ParallelCompactData::ChunkData* c,
-                            bool newline = true)
+print_initial_summary_region(size_t i,
+                             const ParallelCompactData::RegionData* c,
+                             bool newline = true)
 {
   tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
              i, c->destination(),
              c->partial_obj_size(), c->live_obj_size(),
-             c->data_size(), c->source_chunk(), c->destination_count());
+             c->data_size(), c->source_region(), c->destination_count());
   if (newline) tty->cr();
 }
 
@@ -198,47 +199,48 @@
     return;
   }
 
-  const size_t chunk_size = ParallelCompactData::ChunkSize;
-  HeapWord* const top_aligned_up = summary_data.chunk_align_up(space->top());
-  const size_t end_chunk = summary_data.addr_to_chunk_idx(top_aligned_up);
-  const ParallelCompactData::ChunkData* c = summary_data.chunk(end_chunk - 1);
+  const size_t region_size = ParallelCompactData::RegionSize;
+  typedef ParallelCompactData::RegionData RegionData;
+  HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
+  const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
+  const RegionData* c = summary_data.region(end_region - 1);
   HeapWord* end_addr = c->destination() + c->data_size();
   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 
-  // Print (and count) the full chunks at the beginning of the space.
-  size_t full_chunk_count = 0;
-  size_t i = summary_data.addr_to_chunk_idx(space->bottom());
-  while (i < end_chunk && summary_data.chunk(i)->data_size() == chunk_size) {
-    print_initial_summary_chunk(i, summary_data.chunk(i));
-    ++full_chunk_count;
+  // Print (and count) the full regions at the beginning of the space.
+  size_t full_region_count = 0;
+  size_t i = summary_data.addr_to_region_idx(space->bottom());
+  while (i < end_region && summary_data.region(i)->data_size() == region_size) {
+    print_initial_summary_region(i, summary_data.region(i));
+    ++full_region_count;
     ++i;
   }
 
-  size_t live_to_right = live_in_space - full_chunk_count * chunk_size;
+  size_t live_to_right = live_in_space - full_region_count * region_size;
 
   double max_reclaimed_ratio = 0.0;
-  size_t max_reclaimed_ratio_chunk = 0;
+  size_t max_reclaimed_ratio_region = 0;
   size_t max_dead_to_right = 0;
   size_t max_live_to_right = 0;
 
-  // Print the 'reclaimed ratio' for chunks while there is something live in the
-  // chunk or to the right of it.  The remaining chunks are empty (and
+  // Print the 'reclaimed ratio' for regions while there is something live in
+  // the region or to the right of it.  The remaining regions are empty (and
   // uninteresting), and computing the ratio will result in division by 0.
-  while (i < end_chunk && live_to_right > 0) {
-    c = summary_data.chunk(i);
-    HeapWord* const chunk_addr = summary_data.chunk_to_addr(i);
-    const size_t used_to_right = pointer_delta(space->top(), chunk_addr);
+  while (i < end_region && live_to_right > 0) {
+    c = summary_data.region(i);
+    HeapWord* const region_addr = summary_data.region_to_addr(i);
+    const size_t used_to_right = pointer_delta(space->top(), region_addr);
     const size_t dead_to_right = used_to_right - live_to_right;
     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 
     if (reclaimed_ratio > max_reclaimed_ratio) {
             max_reclaimed_ratio = reclaimed_ratio;
-            max_reclaimed_ratio_chunk = i;
+            max_reclaimed_ratio_region = i;
             max_dead_to_right = dead_to_right;
             max_live_to_right = live_to_right;
     }
 
-    print_initial_summary_chunk(i, c, false);
+    print_initial_summary_region(i, c, false);
     tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
                   reclaimed_ratio, dead_to_right, live_to_right);
 
@@ -246,14 +248,14 @@
     ++i;
   }
 
-  // Any remaining chunks are empty.  Print one more if there is one.
-  if (i < end_chunk) {
-    print_initial_summary_chunk(i, summary_data.chunk(i));
+  // Any remaining regions are empty.  Print one more if there is one.
+  if (i < end_region) {
+    print_initial_summary_region(i, summary_data.region(i));
   }
 
   tty->print_cr("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
                 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
-                max_reclaimed_ratio_chunk, max_dead_to_right,
+                max_reclaimed_ratio_region, max_dead_to_right,
                 max_live_to_right, max_reclaimed_ratio);
 }
 
@@ -285,9 +287,9 @@
 {
   _region_start = 0;
 
-  _chunk_vspace = 0;
-  _chunk_data = 0;
-  _chunk_count = 0;
+  _region_vspace = 0;
+  _region_data = 0;
+  _region_count = 0;
 
   _block_vspace = 0;
   _block_data = 0;
@@ -300,16 +302,16 @@
   const size_t region_size = covered_region.word_size();
   DEBUG_ONLY(_region_end = _region_start + region_size;)
 
-  assert(chunk_align_down(_region_start) == _region_start,
+  assert(region_align_down(_region_start) == _region_start,
          "region start not aligned");
-  assert((region_size & ChunkSizeOffsetMask) == 0,
-         "region size not a multiple of ChunkSize");
-
-  bool result = initialize_chunk_data(region_size);
+  assert((region_size & RegionSizeOffsetMask) == 0,
+         "region size not a multiple of RegionSize");
+
+  bool result = initialize_region_data(region_size);
 
   // Initialize the block data if it will be used for updating pointers, or if
   // this is a debug build.
-  if (!UseParallelOldGCChunkPointerCalc || trueInDebug) {
+  if (!UseParallelOldGCRegionPointerCalc || trueInDebug) {
     result = result && initialize_block_data(region_size);
   }
 
@@ -342,13 +344,13 @@
   return 0;
 }
 
-bool ParallelCompactData::initialize_chunk_data(size_t region_size)
+bool ParallelCompactData::initialize_region_data(size_t region_size)
 {
-  const size_t count = (region_size + ChunkSizeOffsetMask) >> Log2ChunkSize;
-  _chunk_vspace = create_vspace(count, sizeof(ChunkData));
-  if (_chunk_vspace != 0) {
-    _chunk_data = (ChunkData*)_chunk_vspace->reserved_low_addr();
-    _chunk_count = count;
+  const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
+  _region_vspace = create_vspace(count, sizeof(RegionData));
+  if (_region_vspace != 0) {
+    _region_data = (RegionData*)_region_vspace->reserved_low_addr();
+    _region_count = count;
     return true;
   }
   return false;
@@ -371,35 +373,35 @@
   if (_block_data) {
     memset(_block_data, 0, _block_vspace->committed_size());
   }
-  memset(_chunk_data, 0, _chunk_vspace->committed_size());
+  memset(_region_data, 0, _region_vspace->committed_size());
 }
 
-void ParallelCompactData::clear_range(size_t beg_chunk, size_t end_chunk) {
-  assert(beg_chunk <= _chunk_count, "beg_chunk out of range");
-  assert(end_chunk <= _chunk_count, "end_chunk out of range");
-  assert(ChunkSize % BlockSize == 0, "ChunkSize not a multiple of BlockSize");
-
-  const size_t chunk_cnt = end_chunk - beg_chunk;
+void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
+  assert(beg_region <= _region_count, "beg_region out of range");
+  assert(end_region <= _region_count, "end_region out of range");
+  assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
+
+  const size_t region_cnt = end_region - beg_region;
 
   if (_block_data) {
-    const size_t blocks_per_chunk = ChunkSize / BlockSize;
-    const size_t beg_block = beg_chunk * blocks_per_chunk;
-    const size_t block_cnt = chunk_cnt * blocks_per_chunk;
+    const size_t blocks_per_region = RegionSize / BlockSize;
+    const size_t beg_block = beg_region * blocks_per_region;
+    const size_t block_cnt = region_cnt * blocks_per_region;
     memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
   }
-  memset(_chunk_data + beg_chunk, 0, chunk_cnt * sizeof(ChunkData));
+  memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 }
 
-HeapWord* ParallelCompactData::partial_obj_end(size_t chunk_idx) const
+HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 {
-  const ChunkData* cur_cp = chunk(chunk_idx);
-  const ChunkData* const end_cp = chunk(chunk_count() - 1);
-
-  HeapWord* result = chunk_to_addr(chunk_idx);
+  const RegionData* cur_cp = region(region_idx);
+  const RegionData* const end_cp = region(region_count() - 1);
+
+  HeapWord* result = region_to_addr(region_idx);
   if (cur_cp < end_cp) {
     do {
       result += cur_cp->partial_obj_size();
-    } while (cur_cp->partial_obj_size() == ChunkSize && ++cur_cp < end_cp);
+    } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
   }
   return result;
 }
@@ -407,56 +409,56 @@
 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 {
   const size_t obj_ofs = pointer_delta(addr, _region_start);
-  const size_t beg_chunk = obj_ofs >> Log2ChunkSize;
-  const size_t end_chunk = (obj_ofs + len - 1) >> Log2ChunkSize;
+  const size_t beg_region = obj_ofs >> Log2RegionSize;
+  const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 
   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 
-  if (beg_chunk == end_chunk) {
-    // All in one chunk.
-    _chunk_data[beg_chunk].add_live_obj(len);
+  if (beg_region == end_region) {
+    // All in one region.
+    _region_data[beg_region].add_live_obj(len);
     return;
   }
 
-  // First chunk.
-  const size_t beg_ofs = chunk_offset(addr);
-  _chunk_data[beg_chunk].add_live_obj(ChunkSize - beg_ofs);
+  // First region.
+  const size_t beg_ofs = region_offset(addr);
+  _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 
   klassOop klass = ((oop)addr)->klass();
-  // Middle chunks--completely spanned by this object.
-  for (size_t chunk = beg_chunk + 1; chunk < end_chunk; ++chunk) {
-    _chunk_data[chunk].set_partial_obj_size(ChunkSize);
-    _chunk_data[chunk].set_partial_obj_addr(addr);
+  // Middle regions--completely spanned by this object.
+  for (size_t region = beg_region + 1; region < end_region; ++region) {
+    _region_data[region].set_partial_obj_size(RegionSize);
+    _region_data[region].set_partial_obj_addr(addr);
   }
 
-  // Last chunk.
-  const size_t end_ofs = chunk_offset(addr + len - 1);
-  _chunk_data[end_chunk].set_partial_obj_size(end_ofs + 1);
-  _chunk_data[end_chunk].set_partial_obj_addr(addr);
+  // Last region.
+  const size_t end_ofs = region_offset(addr + len - 1);
+  _region_data[end_region].set_partial_obj_size(end_ofs + 1);
+  _region_data[end_region].set_partial_obj_addr(addr);
 }
 
 void
 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 {
-  assert(chunk_offset(beg) == 0, "not ChunkSize aligned");
-  assert(chunk_offset(end) == 0, "not ChunkSize aligned");
-
-  size_t cur_chunk = addr_to_chunk_idx(beg);
-  const size_t end_chunk = addr_to_chunk_idx(end);
+  assert(region_offset(beg) == 0, "not RegionSize aligned");
+  assert(region_offset(end) == 0, "not RegionSize aligned");
+
+  size_t cur_region = addr_to_region_idx(beg);
+  const size_t end_region = addr_to_region_idx(end);
   HeapWord* addr = beg;
-  while (cur_chunk < end_chunk) {
-    _chunk_data[cur_chunk].set_destination(addr);
-    _chunk_data[cur_chunk].set_destination_count(0);
-    _chunk_data[cur_chunk].set_source_chunk(cur_chunk);
-    _chunk_data[cur_chunk].set_data_location(addr);
-
-    // Update live_obj_size so the chunk appears completely full.
-    size_t live_size = ChunkSize - _chunk_data[cur_chunk].partial_obj_size();
-    _chunk_data[cur_chunk].set_live_obj_size(live_size);
-
-    ++cur_chunk;
-    addr += ChunkSize;
+  while (cur_region < end_region) {
+    _region_data[cur_region].set_destination(addr);
+    _region_data[cur_region].set_destination_count(0);
+    _region_data[cur_region].set_source_region(cur_region);
+    _region_data[cur_region].set_data_location(addr);
+
+    // Update live_obj_size so the region appears completely full.
+    size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
+    _region_data[cur_region].set_live_obj_size(live_size);
+
+    ++cur_region;
+    addr += RegionSize;
   }
 }
 
@@ -465,7 +467,7 @@
                                     HeapWord** target_next,
                                     HeapWord** source_next) {
   // This is too strict.
-  // assert(chunk_offset(source_beg) == 0, "not ChunkSize aligned");
+  // assert(region_offset(source_beg) == 0, "not RegionSize aligned");
 
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("tb=" PTR_FORMAT " te=" PTR_FORMAT " "
@@ -477,85 +479,86 @@
                   source_next != 0 ? *source_next : (HeapWord*) 0);
   }
 
-  size_t cur_chunk = addr_to_chunk_idx(source_beg);
-  const size_t end_chunk = addr_to_chunk_idx(chunk_align_up(source_end));
+  size_t cur_region = addr_to_region_idx(source_beg);
+  const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 
   HeapWord *dest_addr = target_beg;
-  while (cur_chunk < end_chunk) {
-    size_t words = _chunk_data[cur_chunk].data_size();
+  while (cur_region < end_region) {
+    size_t words = _region_data[cur_region].data_size();
 
 #if     1
     assert(pointer_delta(target_end, dest_addr) >= words,
            "source region does not fit into target region");
 #else
-    // XXX - need some work on the corner cases here.  If the chunk does not
-    // fit, then must either make sure any partial_obj from the chunk fits, or
-    // 'undo' the initial part of the partial_obj that is in the previous chunk.
+    // XXX - need some work on the corner cases here.  If the region does not
+    // fit, then must either make sure any partial_obj from the region fits, or
+    // "undo" the initial part of the partial_obj that is in the previous
+    // region.
     if (dest_addr + words >= target_end) {
       // Let the caller know where to continue.
       *target_next = dest_addr;
-      *source_next = chunk_to_addr(cur_chunk);
+      *source_next = region_to_addr(cur_region);
       return false;
     }
 #endif  // #if 1
 
-    _chunk_data[cur_chunk].set_destination(dest_addr);
-
-    // Set the destination_count for cur_chunk, and if necessary, update
-    // source_chunk for a destination chunk.  The source_chunk field is updated
-    // if cur_chunk is the first (left-most) chunk to be copied to a destination
-    // chunk.
+    _region_data[cur_region].set_destination(dest_addr);
+
+    // Set the destination_count for cur_region, and if necessary, update
+    // source_region for a destination region.  The source_region field is
+    // updated if cur_region is the first (left-most) region to be copied to a
+    // destination region.
     //
-    // The destination_count calculation is a bit subtle.  A chunk that has data
-    // that compacts into itself does not count itself as a destination.  This
-    // maintains the invariant that a zero count means the chunk is available
-    // and can be claimed and then filled.
+    // The destination_count calculation is a bit subtle.  A region that has
+    // data that compacts into itself does not count itself as a destination.
+    // This maintains the invariant that a zero count means the region is
+    // available and can be claimed and then filled.
     if (words > 0) {
       HeapWord* const last_addr = dest_addr + words - 1;
-      const size_t dest_chunk_1 = addr_to_chunk_idx(dest_addr);
-      const size_t dest_chunk_2 = addr_to_chunk_idx(last_addr);
+      const size_t dest_region_1 = addr_to_region_idx(dest_addr);
+      const size_t dest_region_2 = addr_to_region_idx(last_addr);
 #if     0
-      // Initially assume that the destination chunks will be the same and
+      // Initially assume that the destination regions will be the same and
       // adjust the value below if necessary.  Under this assumption, if
-      // cur_chunk == dest_chunk_2, then cur_chunk will be compacted completely
-      // into itself.
-      uint destination_count = cur_chunk == dest_chunk_2 ? 0 : 1;
-      if (dest_chunk_1 != dest_chunk_2) {
-        // Destination chunks differ; adjust destination_count.
+      // cur_region == dest_region_2, then cur_region will be compacted
+      // completely into itself.
+      uint destination_count = cur_region == dest_region_2 ? 0 : 1;
+      if (dest_region_1 != dest_region_2) {
+        // Destination regions differ; adjust destination_count.
         destination_count += 1;
-        // Data from cur_chunk will be copied to the start of dest_chunk_2.
-        _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);
-      } else if (chunk_offset(dest_addr) == 0) {
-        // Data from cur_chunk will be copied to the start of the destination
-        // chunk.
-        _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);
+        // Data from cur_region will be copied to the start of dest_region_2.
+        _region_data[dest_region_2].set_source_region(cur_region);
+      } else if (region_offset(dest_addr) == 0) {
+        // Data from cur_region will be copied to the start of the destination
+        // region.
+        _region_data[dest_region_1].set_source_region(cur_region);
       }
 #else
-      // Initially assume that the destination chunks will be different and
+      // Initially assume that the destination regions will be different and
       // adjust the value below if necessary.  Under this assumption, if
-      // cur_chunk == dest_chunk2, then cur_chunk will be compacted partially
-      // into dest_chunk_1 and partially into itself.
-      uint destination_count = cur_chunk == dest_chunk_2 ? 1 : 2;
-      if (dest_chunk_1 != dest_chunk_2) {
-        // Data from cur_chunk will be copied to the start of dest_chunk_2.
-        _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);
+      // cur_region == dest_region2, then cur_region will be compacted partially
+      // into dest_region_1 and partially into itself.
+      uint destination_count = cur_region == dest_region_2 ? 1 : 2;
+      if (dest_region_1 != dest_region_2) {
+        // Data from cur_region will be copied to the start of dest_region_2.
+        _region_data[dest_region_2].set_source_region(cur_region);
       } else {
-        // Destination chunks are the same; adjust destination_count.
+        // Destination regions are the same; adjust destination_count.
         destination_count -= 1;
-        if (chunk_offset(dest_addr) == 0) {
-          // Data from cur_chunk will be copied to the start of the destination
-          // chunk.
-          _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);
+        if (region_offset(dest_addr) == 0) {
+          // Data from cur_region will be copied to the start of the destination
+          // region.
+          _region_data[dest_region_1].set_source_region(cur_region);
         }
       }
 #endif  // #if 0
 
-      _chunk_data[cur_chunk].set_destination_count(destination_count);
-      _chunk_data[cur_chunk].set_data_location(chunk_to_addr(cur_chunk));
+      _region_data[cur_region].set_destination_count(destination_count);
+      _region_data[cur_region].set_data_location(region_to_addr(cur_region));
       dest_addr += words;
     }
 
-    ++cur_chunk;
+    ++cur_region;
   }
 
   *target_next = dest_addr;
@@ -565,8 +568,8 @@
 bool ParallelCompactData::partial_obj_ends_in_block(size_t block_index) {
   HeapWord* block_addr = block_to_addr(block_index);
   HeapWord* block_end_addr = block_addr + BlockSize;
-  size_t chunk_index = addr_to_chunk_idx(block_addr);
-  HeapWord* partial_obj_end_addr = partial_obj_end(chunk_index);
+  size_t region_index = addr_to_region_idx(block_addr);
+  HeapWord* partial_obj_end_addr = partial_obj_end(region_index);
 
   // An object that ends at the end of the block, ends
   // in the block (the last word of the object is to
@@ -581,8 +584,8 @@
 
 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
   HeapWord* result = NULL;
-  if (UseParallelOldGCChunkPointerCalc) {
-    result = chunk_calc_new_pointer(addr);
+  if (UseParallelOldGCRegionPointerCalc) {
+    result = region_calc_new_pointer(addr);
   } else {
     result = block_calc_new_pointer(addr);
   }
@@ -595,7 +598,7 @@
 // the object is dead.  But don't wast the cycles to explicitly check
 // that it is dead since only live objects should be passed in.
 
-HeapWord* ParallelCompactData::chunk_calc_new_pointer(HeapWord* addr) {
+HeapWord* ParallelCompactData::region_calc_new_pointer(HeapWord* addr) {
   assert(addr != NULL, "Should detect NULL oop earlier");
   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 #ifdef ASSERT
@@ -605,30 +608,30 @@
 #endif
   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 
-  // Chunk covering the object.
-  size_t chunk_index = addr_to_chunk_idx(addr);
-  const ChunkData* const chunk_ptr = chunk(chunk_index);
-  HeapWord* const chunk_addr = chunk_align_down(addr);
-
-  assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");
-  assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");
-
-  HeapWord* result = chunk_ptr->destination();
-
-  // If all the data in the chunk is live, then the new location of the object
-  // can be calculated from the destination of the chunk plus the offset of the
-  // object in the chunk.
-  if (chunk_ptr->data_size() == ChunkSize) {
-    result += pointer_delta(addr, chunk_addr);
+  // Region covering the object.
+  size_t region_index = addr_to_region_idx(addr);
+  const RegionData* const region_ptr = region(region_index);
+  HeapWord* const region_addr = region_align_down(addr);
+
+  assert(addr < region_addr + RegionSize, "Region does not cover object");
+  assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
+
+  HeapWord* result = region_ptr->destination();
+
+  // If all the data in the region is live, then the new location of the object
+  // can be calculated from the destination of the region plus the offset of the
+  // object in the region.
+  if (region_ptr->data_size() == RegionSize) {
+    result += pointer_delta(addr, region_addr);
     return result;
   }
 
   // The new location of the object is
-  //    chunk destination +
-  //    size of the partial object extending onto the chunk +
-  //    sizes of the live objects in the Chunk that are to the left of addr
-  const size_t partial_obj_size = chunk_ptr->partial_obj_size();
-  HeapWord* const search_start = chunk_addr + partial_obj_size;
+  //    region destination +
+  //    size of the partial object extending onto the region +
+  //    sizes of the live objects in the Region that are to the left of addr
+  const size_t partial_obj_size = region_ptr->partial_obj_size();
+  HeapWord* const search_start = region_addr + partial_obj_size;
 
   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
@@ -648,37 +651,37 @@
 #endif
   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 
-  // Chunk covering the object.
-  size_t chunk_index = addr_to_chunk_idx(addr);
-  const ChunkData* const chunk_ptr = chunk(chunk_index);
-  HeapWord* const chunk_addr = chunk_align_down(addr);
-
-  assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");
-  assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");
-
-  HeapWord* result = chunk_ptr->destination();
-
-  // If all the data in the chunk is live, then the new location of the object
-  // can be calculated from the destination of the chunk plus the offset of the
-  // object in the chunk.
-  if (chunk_ptr->data_size() == ChunkSize) {
-    result += pointer_delta(addr, chunk_addr);
+  // Region covering the object.
+  size_t region_index = addr_to_region_idx(addr);
+  const RegionData* const region_ptr = region(region_index);
+  HeapWord* const region_addr = region_align_down(addr);
+
+  assert(addr < region_addr + RegionSize, "Region does not cover object");
+  assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
+
+  HeapWord* result = region_ptr->destination();
+
+  // If all the data in the region is live, then the new location of the object
+  // can be calculated from the destination of the region plus the offset of the
+  // object in the region.
+  if (region_ptr->data_size() == RegionSize) {
+    result += pointer_delta(addr, region_addr);
     return result;
   }
 
   // The new location of the object is
-  //    chunk destination +
+  //    region destination +
   //    block offset +
   //    sizes of the live objects in the Block that are to the left of addr
   const size_t block_offset = addr_to_block_ptr(addr)->offset();
-  HeapWord* const search_start = chunk_addr + block_offset;
+  HeapWord* const search_start = region_addr + block_offset;
 
   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
 
   result += block_offset + live_to_left;
   assert(result <= addr, "object cannot move to the right");
-  assert(result == chunk_calc_new_pointer(addr), "Should match");
+  assert(result == region_calc_new_pointer(addr), "Should match");
   return result;
 }
 
@@ -705,15 +708,15 @@
 
 void ParallelCompactData::verify_clear()
 {
-  verify_clear(_chunk_vspace);
+  verify_clear(_region_vspace);
   verify_clear(_block_vspace);
 }
 #endif  // #ifdef ASSERT
 
 #ifdef NOT_PRODUCT
-ParallelCompactData::ChunkData* debug_chunk(size_t chunk_index) {
+ParallelCompactData::RegionData* debug_region(size_t region_index) {
   ParallelCompactData& sd = PSParallelCompact::summary_data();
-  return sd.chunk(chunk_index);
+  return sd.region(region_index);
 }
 #endif
 
@@ -866,10 +869,10 @@
   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
   _mark_bitmap.clear_range(beg_bit, end_bit);
 
-  const size_t beg_chunk = _summary_data.addr_to_chunk_idx(bot);
-  const size_t end_chunk =
-    _summary_data.addr_to_chunk_idx(_summary_data.chunk_align_up(max_top));
-  _summary_data.clear_range(beg_chunk, end_chunk);
+  const size_t beg_region = _summary_data.addr_to_region_idx(bot);
+  const size_t end_region =
+    _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
+  _summary_data.clear_range(beg_region, end_region);
 }
 
 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
@@ -985,19 +988,19 @@
 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
                                                     bool maximum_compaction)
 {
-  const size_t chunk_size = ParallelCompactData::ChunkSize;
+  const size_t region_size = ParallelCompactData::RegionSize;
   const ParallelCompactData& sd = summary_data();
 
   const MutableSpace* const space = _space_info[id].space();
-  HeapWord* const top_aligned_up = sd.chunk_align_up(space->top());
-  const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(space->bottom());
-  const ChunkData* const end_cp = sd.addr_to_chunk_ptr(top_aligned_up);
-
-  // Skip full chunks at the beginning of the space--they are necessarily part
+  HeapWord* const top_aligned_up = sd.region_align_up(space->top());
+  const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
+  const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
+
+  // Skip full regions at the beginning of the space--they are necessarily part
   // of the dense prefix.
   size_t full_count = 0;
-  const ChunkData* cp;
-  for (cp = beg_cp; cp < end_cp && cp->data_size() == chunk_size; ++cp) {
+  const RegionData* cp;
+  for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
     ++full_count;
   }
 
@@ -1006,7 +1009,7 @@
   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
   if (maximum_compaction || cp == end_cp || interval_ended) {
     _maximum_compaction_gc_num = total_invocations();
-    return sd.chunk_to_addr(cp);
+    return sd.region_to_addr(cp);
   }
 
   HeapWord* const new_top = _space_info[id].new_top();
@@ -1029,52 +1032,53 @@
   }
 
   // XXX - Use binary search?
-  HeapWord* dense_prefix = sd.chunk_to_addr(cp);
-  const ChunkData* full_cp = cp;
-  const ChunkData* const top_cp = sd.addr_to_chunk_ptr(space->top() - 1);
+  HeapWord* dense_prefix = sd.region_to_addr(cp);
+  const RegionData* full_cp = cp;
+  const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
   while (cp < end_cp) {
-    HeapWord* chunk_destination = cp->destination();
-    const size_t cur_deadwood = pointer_delta(dense_prefix, chunk_destination);
+    HeapWord* region_destination = cp->destination();
+    const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
     if (TraceParallelOldGCDensePrefix && Verbose) {
       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
-                    sd.chunk(cp), chunk_destination,
+                    sd.region(cp), region_destination,
                     dense_prefix, cur_deadwood);
     }
 
     if (cur_deadwood >= deadwood_goal) {
-      // Found the chunk that has the correct amount of deadwood to the left.
-      // This typically occurs after crossing a fairly sparse set of chunks, so
-      // iterate backwards over those sparse chunks, looking for the chunk that
-      // has the lowest density of live objects 'to the right.'
-      size_t space_to_left = sd.chunk(cp) * chunk_size;
+      // Found the region that has the correct amount of deadwood to the left.
+      // This typically occurs after crossing a fairly sparse set of regions, so
+      // iterate backwards over those sparse regions, looking for the region
+      // that has the lowest density of live objects 'to the right.'
+      size_t space_to_left = sd.region(cp) * region_size;
       size_t live_to_left = space_to_left - cur_deadwood;
       size_t space_to_right = space_capacity - space_to_left;
       size_t live_to_right = space_live - live_to_left;
       double density_to_right = double(live_to_right) / space_to_right;
       while (cp > full_cp) {
         --cp;
-        const size_t prev_chunk_live_to_right = live_to_right - cp->data_size();
-        const size_t prev_chunk_space_to_right = space_to_right + chunk_size;
-        double prev_chunk_density_to_right =
-          double(prev_chunk_live_to_right) / prev_chunk_space_to_right;
-        if (density_to_right <= prev_chunk_density_to_right) {
+        const size_t prev_region_live_to_right = live_to_right -
+          cp->data_size();
+        const size_t prev_region_space_to_right = space_to_right + region_size;
+        double prev_region_density_to_right =
+          double(prev_region_live_to_right) / prev_region_space_to_right;
+        if (density_to_right <= prev_region_density_to_right) {
           return dense_prefix;
         }
         if (TraceParallelOldGCDensePrefix && Verbose) {
           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
-                        "pc_d2r=%10.8f", sd.chunk(cp), density_to_right,
-                        prev_chunk_density_to_right);
+                        "pc_d2r=%10.8f", sd.region(cp), density_to_right,
+                        prev_region_density_to_right);
         }
-        dense_prefix -= chunk_size;
-        live_to_right = prev_chunk_live_to_right;
-        space_to_right = prev_chunk_space_to_right;
-        density_to_right = prev_chunk_density_to_right;
+        dense_prefix -= region_size;
+        live_to_right = prev_region_live_to_right;
+        space_to_right = prev_region_space_to_right;
+        density_to_right = prev_region_density_to_right;
       }
       return dense_prefix;
     }
 
-    dense_prefix += chunk_size;
+    dense_prefix += region_size;
     ++cp;
   }
 
@@ -1087,8 +1091,8 @@
                                                  const bool maximum_compaction,
                                                  HeapWord* const addr)
 {
-  const size_t chunk_idx = summary_data().addr_to_chunk_idx(addr);
-  ChunkData* const cp = summary_data().chunk(chunk_idx);
+  const size_t region_idx = summary_data().addr_to_region_idx(addr);
+  RegionData* const cp = summary_data().region(region_idx);
   const MutableSpace* const space = _space_info[id].space();
   HeapWord* const new_top = _space_info[id].new_top();
 
@@ -1104,7 +1108,7 @@
                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
                 " ratio=%10.8f",
-                algorithm, addr, chunk_idx,
+                algorithm, addr, region_idx,
                 space_live,
                 dead_to_left, dead_to_left_pct,
                 dead_to_right, live_to_right,
@@ -1166,52 +1170,52 @@
   return MAX2(limit, 0.0);
 }
 
-ParallelCompactData::ChunkData*
-PSParallelCompact::first_dead_space_chunk(const ChunkData* beg,
-                                          const ChunkData* end)
+ParallelCompactData::RegionData*
+PSParallelCompact::first_dead_space_region(const RegionData* beg,
+                                           const RegionData* end)
 {
-  const size_t chunk_size = ParallelCompactData::ChunkSize;
+  const size_t region_size = ParallelCompactData::RegionSize;
   ParallelCompactData& sd = summary_data();
-  size_t left = sd.chunk(beg);
-  size_t right = end > beg ? sd.chunk(end) - 1 : left;
+  size_t left = sd.region(beg);
+  size_t right = end > beg ? sd.region(end) - 1 : left;
 
   // Binary search.
   while (left < right) {
     // Equivalent to (left + right) / 2, but does not overflow.
     const size_t middle = left + (right - left) / 2;
-    ChunkData* const middle_ptr = sd.chunk(middle);
+    RegionData* const middle_ptr = sd.region(middle);
     HeapWord* const dest = middle_ptr->destination();
-    HeapWord* const addr = sd.chunk_to_addr(middle);
+    HeapWord* const addr = sd.region_to_addr(middle);
     assert(dest != NULL, "sanity");
     assert(dest <= addr, "must move left");
 
     if (middle > left && dest < addr) {
       right = middle - 1;
-    } else if (middle < right && middle_ptr->data_size() == chunk_size) {
+    } else if (middle < right && middle_ptr->data_size() == region_size) {
       left = middle + 1;
     } else {
       return middle_ptr;
     }
   }
-  return sd.chunk(left);
+  return sd.region(left);
 }
 
-ParallelCompactData::ChunkData*
-PSParallelCompact::dead_wood_limit_chunk(const ChunkData* beg,
-                                         const ChunkData* end,
-                                         size_t dead_words)
+ParallelCompactData::RegionData*
+PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
+                                          const RegionData* end,
+                                          size_t dead_words)
 {
   ParallelCompactData& sd = summary_data();
-  size_t left = sd.chunk(beg);
-  size_t right = end > beg ? sd.chunk(end) - 1 : left;
+  size_t left = sd.region(beg);
+  size_t right = end > beg ? sd.region(end) - 1 : left;
 
   // Binary search.
   while (left < right) {
     // Equivalent to (left + right) / 2, but does not overflow.
     const size_t middle = left + (right - left) / 2;
-    ChunkData* const middle_ptr = sd.chunk(middle);
+    RegionData* const middle_ptr = sd.region(middle);
     HeapWord* const dest = middle_ptr->destination();
-    HeapWord* const addr = sd.chunk_to_addr(middle);
+    HeapWord* const addr = sd.region_to_addr(middle);
     assert(dest != NULL, "sanity");
     assert(dest <= addr, "must move left");
 
@@ -1224,13 +1228,13 @@
       return middle_ptr;
     }
   }
-  return sd.chunk(left);
+  return sd.region(left);
 }
 
 // The result is valid during the summary phase, after the initial summarization
 // of each space into itself, and before final summarization.
 inline double
-PSParallelCompact::reclaimed_ratio(const ChunkData* const cp,
+PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
                                    HeapWord* const bottom,
                                    HeapWord* const top,
                                    HeapWord* const new_top)
@@ -1244,12 +1248,13 @@
   assert(top >= new_top, "summary data problem?");
   assert(new_top > bottom, "space is empty; should not be here");
   assert(new_top >= cp->destination(), "sanity");
-  assert(top >= sd.chunk_to_addr(cp), "sanity");
+  assert(top >= sd.region_to_addr(cp), "sanity");
 
   HeapWord* const destination = cp->destination();
   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
   const size_t compacted_region_live = pointer_delta(new_top, destination);
-  const size_t compacted_region_used = pointer_delta(top, sd.chunk_to_addr(cp));
+  const size_t compacted_region_used = pointer_delta(top,
+                                                     sd.region_to_addr(cp));
   const size_t reclaimable = compacted_region_used - compacted_region_live;
 
   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
@@ -1257,39 +1262,40 @@
 }
 
 // Return the address of the end of the dense prefix, a.k.a. the start of the
-// compacted region.  The address is always on a chunk boundary.
+// compacted region.  The address is always on a region boundary.
 //
-// Completely full chunks at the left are skipped, since no compaction can occur
-// in those chunks.  Then the maximum amount of dead wood to allow is computed,
-// based on the density (amount live / capacity) of the generation; the chunk
-// with approximately that amount of dead space to the left is identified as the
-// limit chunk.  Chunks between the last completely full chunk and the limit
-// chunk are scanned and the one that has the best (maximum) reclaimed_ratio()
-// is selected.
+// Completely full regions at the left are skipped, since no compaction can
+// occur in those regions.  Then the maximum amount of dead wood to allow is
+// computed, based on the density (amount live / capacity) of the generation;
+// the region with approximately that amount of dead space to the left is
+// identified as the limit region.  Regions between the last completely full
+// region and the limit region are scanned and the one that has the best
+// (maximum) reclaimed_ratio() is selected.
 HeapWord*
 PSParallelCompact::compute_dense_prefix(const SpaceId id,
                                         bool maximum_compaction)
 {
-  const size_t chunk_size = ParallelCompactData::ChunkSize;
+  const size_t region_size = ParallelCompactData::RegionSize;
   const ParallelCompactData& sd = summary_data();
 
   const MutableSpace* const space = _space_info[id].space();
   HeapWord* const top = space->top();
-  HeapWord* const top_aligned_up = sd.chunk_align_up(top);
+  HeapWord* const top_aligned_up = sd.region_align_up(top);
   HeapWord* const new_top = _space_info[id].new_top();
-  HeapWord* const new_top_aligned_up = sd.chunk_align_up(new_top);
+  HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
   HeapWord* const bottom = space->bottom();
-  const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(bottom);
-  const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up);
-  const ChunkData* const new_top_cp = sd.addr_to_chunk_ptr(new_top_aligned_up);
-
-  // Skip full chunks at the beginning of the space--they are necessarily part
+  const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
+  const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
+  const RegionData* const new_top_cp =
+    sd.addr_to_region_ptr(new_top_aligned_up);
+
+  // Skip full regions at the beginning of the space--they are necessarily part
   // of the dense prefix.
-  const ChunkData* const full_cp = first_dead_space_chunk(beg_cp, new_top_cp);
-  assert(full_cp->destination() == sd.chunk_to_addr(full_cp) ||
+  const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
+  assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
          space->is_empty(), "no dead space allowed to the left");
-  assert(full_cp->data_size() < chunk_size || full_cp == new_top_cp - 1,
-         "chunk must have dead space");
+  assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
+         "region must have dead space");
 
   // The gc number is saved whenever a maximum compaction is done, and used to
   // determine when the maximum compaction interval has expired.  This avoids
@@ -1300,7 +1306,7 @@
     total_invocations() == HeapFirstMaximumCompactionCount;
   if (maximum_compaction || full_cp == top_cp || interval_ended) {
     _maximum_compaction_gc_num = total_invocations();
-    return sd.chunk_to_addr(full_cp);
+    return sd.region_to_addr(full_cp);
   }
 
   const size_t space_live = pointer_delta(new_top, bottom);
@@ -1326,15 +1332,15 @@
                   dead_wood_max, dead_wood_limit);
   }
 
-  // Locate the chunk with the desired amount of dead space to the left.
-  const ChunkData* const limit_cp =
-    dead_wood_limit_chunk(full_cp, top_cp, dead_wood_limit);
-
-  // Scan from the first chunk with dead space to the limit chunk and find the
+  // Locate the region with the desired amount of dead space to the left.
+  const RegionData* const limit_cp =
+    dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
+
+  // Scan from the first region with dead space to the limit region and find the
   // one with the best (largest) reclaimed ratio.
   double best_ratio = 0.0;
-  const ChunkData* best_cp = full_cp;
-  for (const ChunkData* cp = full_cp; cp < limit_cp; ++cp) {
+  const RegionData* best_cp = full_cp;
+  for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
     if (tmp_ratio > best_ratio) {
       best_cp = cp;
@@ -1343,18 +1349,18 @@
   }
 
 #if     0
-  // Something to consider:  if the chunk with the best ratio is 'close to' the
-  // first chunk w/free space, choose the first chunk with free space
-  // ("first-free").  The first-free chunk is usually near the start of the
+  // Something to consider:  if the region with the best ratio is 'close to' the
+  // first region w/free space, choose the first region with free space
+  // ("first-free").  The first-free region is usually near the start of the
   // heap, which means we are copying most of the heap already, so copy a bit
   // more to get complete compaction.
-  if (pointer_delta(best_cp, full_cp, sizeof(ChunkData)) < 4) {
+  if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
     _maximum_compaction_gc_num = total_invocations();
     best_cp = full_cp;
   }
 #endif  // #if 0
 
-  return sd.chunk_to_addr(best_cp);
+  return sd.region_to_addr(best_cp);
 }
 
 void PSParallelCompact::summarize_spaces_quick()
@@ -1372,9 +1378,9 @@
 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
 {
   HeapWord* const dense_prefix_end = dense_prefix(id);
-  const ChunkData* chunk = _summary_data.addr_to_chunk_ptr(dense_prefix_end);
+  const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
-  if (dead_space_crosses_boundary(chunk, dense_prefix_bit)) {
+  if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
     // Only enough dead space is filled so that any remaining dead space to the
     // left is larger than the minimum filler object.  (The remainder is filled
     // during the copy/update phase.)
@@ -1465,7 +1471,7 @@
       fill_dense_prefix_end(id);
     }
 
-    // Compute the destination of each Chunk, and thus each object.
+    // Compute the destination of each Region, and thus each object.
     _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
     _summary_data.summarize(dense_prefix_end, space->end(),
                             dense_prefix_end, space->top(),
@@ -1473,19 +1479,19 @@
   }
 
   if (TraceParallelOldGCSummaryPhase) {
-    const size_t chunk_size = ParallelCompactData::ChunkSize;
+    const size_t region_size = ParallelCompactData::RegionSize;
     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
-    const size_t dp_chunk = _summary_data.addr_to_chunk_idx(dense_prefix_end);
+    const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
     HeapWord* const new_top = _space_info[id].new_top();
-    const HeapWord* nt_aligned_up = _summary_data.chunk_align_up(new_top);
+    const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
-                  "dp_chunk=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
+                  "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
                   id, space->capacity_in_words(), dense_prefix_end,
-                  dp_chunk, dp_words / chunk_size,
-                  cr_words / chunk_size, new_top);
+                  dp_region, dp_words / region_size,
+                  cr_words / region_size, new_top);
   }
 }
 
@@ -1513,7 +1519,7 @@
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("summary_phase:  after summarizing each space to self");
     Universe::print();
-    NOT_PRODUCT(print_chunk_ranges());
+    NOT_PRODUCT(print_region_ranges());
     if (Verbose) {
       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
     }
@@ -1559,14 +1565,15 @@
                               space->bottom(), space->top(),
                               new_top_addr);
 
-      // Clear the source_chunk field for each chunk in the space.
+      // Clear the source_region field for each region in the space.
       HeapWord* const new_top = _space_info[id].new_top();
-      HeapWord* const clear_end = _summary_data.chunk_align_up(new_top);
-      ChunkData* beg_chunk = _summary_data.addr_to_chunk_ptr(space->bottom());
-      ChunkData* end_chunk = _summary_data.addr_to_chunk_ptr(clear_end);
-      while (beg_chunk < end_chunk) {
-        beg_chunk->set_source_chunk(0);
-        ++beg_chunk;
+      HeapWord* const clear_end = _summary_data.region_align_up(new_top);
+      RegionData* beg_region =
+        _summary_data.addr_to_region_ptr(space->bottom());
+      RegionData* end_region = _summary_data.addr_to_region_ptr(clear_end);
+      while (beg_region < end_region) {
+        beg_region->set_source_region(0);
+        ++beg_region;
       }
 
       // Reset the new_top value for the space.
@@ -1574,13 +1581,13 @@
     }
   }
 
-  // Fill in the block data after any changes to the chunks have
+  // Fill in the block data after any changes to the regions have
   // been made.
 #ifdef  ASSERT
   summarize_blocks(cm, perm_space_id);
   summarize_blocks(cm, old_space_id);
 #else
-  if (!UseParallelOldGCChunkPointerCalc) {
+  if (!UseParallelOldGCRegionPointerCalc) {
     summarize_blocks(cm, perm_space_id);
     summarize_blocks(cm, old_space_id);
   }
@@ -1589,7 +1596,7 @@
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("summary_phase:  after final summarization");
     Universe::print();
-    NOT_PRODUCT(print_chunk_ranges());
+    NOT_PRODUCT(print_region_ranges());
     if (Verbose) {
       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
     }
@@ -1598,7 +1605,7 @@
 
 // Fill in the BlockData.
 // Iterate over the spaces and within each space iterate over
-// the chunks and fill in the BlockData for each chunk.
+// the regions and fill in the BlockData for each region.
 
 void PSParallelCompact::summarize_blocks(ParCompactionManager* cm,
                                          SpaceId first_compaction_space_id) {
@@ -1607,40 +1614,41 @@
   for (SpaceId cur_space_id = first_compaction_space_id;
        cur_space_id != last_space_id;
        cur_space_id = next_compaction_space_id(cur_space_id)) {
-    // Iterate over the chunks in the space
-    size_t start_chunk_index =
-      _summary_data.addr_to_chunk_idx(space(cur_space_id)->bottom());
+    // Iterate over the regions in the space
+    size_t start_region_index =
+      _summary_data.addr_to_region_idx(space(cur_space_id)->bottom());
     BitBlockUpdateClosure bbu(mark_bitmap(),
                               cm,
-                              start_chunk_index);
+                              start_region_index);
     // Iterate over blocks.
-    for (size_t chunk_index =  start_chunk_index;
-         chunk_index < _summary_data.chunk_count() &&
-         _summary_data.chunk_to_addr(chunk_index) < space(cur_space_id)->top();
-         chunk_index++) {
-
-      // Reset the closure for the new chunk.  Note that the closure
-      // maintains some data that does not get reset for each chunk
+    for (size_t region_index =  start_region_index;
+         region_index < _summary_data.region_count() &&
+           _summary_data.region_to_addr(region_index) <
+           space(cur_space_id)->top();
+         region_index++) {
+
+      // Reset the closure for the new region.  Note that the closure
+      // maintains some data that does not get reset for each region
       // so a new instance of the closure is no appropriate.
-      bbu.reset_chunk(chunk_index);
+      bbu.reset_region(region_index);
 
       // Start the iteration with the first live object.  This
-      // may return the end of the chunk.  That is acceptable since
+      // may return the end of the region.  That is acceptable since
       // it will properly limit the iterations.
       ParMarkBitMap::idx_t left_offset = mark_bitmap()->addr_to_bit(
-        _summary_data.first_live_or_end_in_chunk(chunk_index));
-
-      // End the iteration at the end of the chunk.
-      HeapWord* chunk_addr = _summary_data.chunk_to_addr(chunk_index);
-      HeapWord* chunk_end = chunk_addr + ParallelCompactData::ChunkSize;
+        _summary_data.first_live_or_end_in_region(region_index));
+
+      // End the iteration at the end of the region.
+      HeapWord* region_addr = _summary_data.region_to_addr(region_index);
+      HeapWord* region_end = region_addr + ParallelCompactData::RegionSize;
       ParMarkBitMap::idx_t right_offset =
-        mark_bitmap()->addr_to_bit(chunk_end);
+        mark_bitmap()->addr_to_bit(region_end);
 
       // Blocks that have not objects starting in them can be
       // skipped because their data will never be used.
       if (left_offset < right_offset) {
 
-        // Iterate through the objects in the chunk.
+        // Iterate through the objects in the region.
         ParMarkBitMap::idx_t last_offset =
           mark_bitmap()->pair_iterate(&bbu, left_offset, right_offset);
 
@@ -1649,7 +1657,7 @@
         // is then the offset for the last start bit.  In this situation
         // the "offset" field for the next block to the right (_cur_block + 1)
         // will not have been update although there may be live data
-        // to the left of the chunk.
+        // to the left of the region.
 
         size_t cur_block_plus_1 = bbu.cur_block() + 1;
         HeapWord* cur_block_plus_1_addr =
@@ -1669,23 +1677,23 @@
  #else
         // The current block has already been updated.  The only block
         // that remains to be updated is the block where the last
-        // object in the chunk starts.
+        // object in the region starts.
         size_t last_block = _summary_data.addr_to_block_idx(last_offset_addr);
  #endif
         assert_bit_is_start(last_offset);
         assert((last_block == _summary_data.block_count()) ||
              (_summary_data.block(last_block)->raw_offset() == 0),
           "Should not have been set");
-        // Is the last block still in the current chunk?  If still
-        // in this chunk, update the last block (the counting that
+        // Is the last block still in the current region?  If still
+        // in this region, update the last block (the counting that
         // included the current block is meant for the offset of the last
-        // block).  If not in this chunk, do nothing.  Should not
-        // update a block in the next chunk.
-        if (ParallelCompactData::chunk_contains_block(bbu.chunk_index(),
-                                                      last_block)) {
+        // block).  If not in this region, do nothing.  Should not
+        // update a block in the next region.
+        if (ParallelCompactData::region_contains_block(bbu.region_index(),
+                                                       last_block)) {
           if (last_offset < right_offset) {
-            // The last object started in this chunk but ends beyond
-            // this chunk.  Update the block for this last object.
+            // The last object started in this region but ends beyond
+            // this region.  Update the block for this last object.
             assert(mark_bitmap()->is_marked(last_offset), "Should be marked");
             // No end bit was found.  The closure takes care of
             // the cases where
@@ -1693,7 +1701,7 @@
             //   an objects starts and ends in the next block
             // It does not handle the case where an object is
             // the first object in a later block and extends
-            // past the end of the chunk (i.e., the closure
+            // past the end of the region (i.e., the closure
             // only handles complete objects that are in the range
             // it is given).  That object is handed back here
             // for any special consideration necessary.
@@ -1709,7 +1717,7 @@
             // the AA+1 is the trigger that updates AA.  Objects are being
             // counted in the current block for updaing a following
             // block.  An object may start in later block
-            // block but may extend beyond the last block in the chunk.
+            // block but may extend beyond the last block in the region.
             // Updates are only done when the end of an object has been
             // found. If the last object (covered by block L) starts
             // beyond the current block, then no object ends in L (otherwise
@@ -1717,7 +1725,7 @@
             // a start bit.
             //
             // Else the last objects start in the current block and ends
-            // beyond the chunk.  The current block has already been
+            // beyond the region.  The current block has already been
             // updated and there is no later block (with an object
             // starting in it) that needs to be updated.
             //
@@ -1728,14 +1736,14 @@
               //   The start of the object is on a later block
               // (to the right of the current block and there are no
               // complete live objects to the left of this last object
-              // within the chunk.
+              // within the region.
               //   The first bit in the block is for the start of the
               // last object.
               _summary_data.block(last_block)->set_start_bit_offset(
                 bbu.live_data_left());
             } else {
               //   The start of the last object was found in
-              // the current chunk (which has already
+              // the current region (which has already
               // been updated).
               assert(bbu.cur_block() ==
                       _summary_data.addr_to_block_idx(last_offset_addr),
@@ -1743,15 +1751,15 @@
             }
 #ifdef ASSERT
             // Is there enough block information to find this object?
-            // The destination of the chunk has not been set so the
+            // The destination of the region has not been set so the
             // values returned by calc_new_pointer() and
             // block_calc_new_pointer() will only be
             // offsets.  But they should agree.
-            HeapWord* moved_obj_with_chunks =
-              _summary_data.chunk_calc_new_pointer(last_offset_addr);
+            HeapWord* moved_obj_with_regions =
+              _summary_data.region_calc_new_pointer(last_offset_addr);
             HeapWord* moved_obj_with_blocks =
               _summary_data.calc_new_pointer(last_offset_addr);
-            assert(moved_obj_with_chunks == moved_obj_with_blocks,
+            assert(moved_obj_with_regions == moved_obj_with_blocks,
               "Block calculation is wrong");
 #endif
           } else if (last_block < _summary_data.block_count()) {
@@ -1764,38 +1772,38 @@
 #ifdef ASSERT
         // Is there enough block information to find this object?
           HeapWord* left_offset_addr = mark_bitmap()->bit_to_addr(left_offset);
-        HeapWord* moved_obj_with_chunks =
+        HeapWord* moved_obj_with_regions =
           _summary_data.calc_new_pointer(left_offset_addr);
         HeapWord* moved_obj_with_blocks =
           _summary_data.calc_new_pointer(left_offset_addr);
-          assert(moved_obj_with_chunks == moved_obj_with_blocks,
+          assert(moved_obj_with_regions == moved_obj_with_blocks,
           "Block calculation is wrong");
 #endif
 
-        // Is there another block after the end of this chunk?
+        // Is there another block after the end of this region?
 #ifdef ASSERT
         if (last_block < _summary_data.block_count()) {
         // No object may have been found in a block.  If that
-        // block is at the end of the chunk, the iteration will
+        // block is at the end of the region, the iteration will
         // terminate without incrementing the current block so
         // that the current block is not the last block in the
-        // chunk.  That situation precludes asserting that the
-        // current block is the last block in the chunk.  Assert
+        // region.  That situation precludes asserting that the
+        // current block is the last block in the region.  Assert
         // the lesser condition that the current block does not
-        // exceed the chunk.
+        // exceed the region.
           assert(_summary_data.block_to_addr(last_block) <=
-               (_summary_data.chunk_to_addr(chunk_index) +
-                 ParallelCompactData::ChunkSize),
-              "Chunk and block inconsistency");
+               (_summary_data.region_to_addr(region_index) +
+                 ParallelCompactData::RegionSize),
+              "Region and block inconsistency");
           assert(last_offset <= right_offset, "Iteration over ran end");
         }
 #endif
       }
 #ifdef ASSERT
       if (PrintGCDetails && Verbose) {
-        if (_summary_data.chunk(chunk_index)->partial_obj_size() == 1) {
+        if (_summary_data.region(region_index)->partial_obj_size() == 1) {
           size_t first_block =
-            chunk_index / ParallelCompactData::BlocksPerChunk;
+            region_index / ParallelCompactData::BlocksPerRegion;
           gclog_or_tty->print_cr("first_block " PTR_FORMAT
             " _offset " PTR_FORMAT
             "_first_is_start_bit %d",
@@ -1845,18 +1853,18 @@
   }
 }
 
-bool ParallelCompactData::chunk_contains(size_t chunk_index, HeapWord* addr) {
-  size_t addr_chunk_index = addr_to_chunk_idx(addr);
-  return chunk_index == addr_chunk_index;
+bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
+  size_t addr_region_index = addr_to_region_idx(addr);
+  return region_index == addr_region_index;
 }
 
-bool ParallelCompactData::chunk_contains_block(size_t chunk_index,
-                                               size_t block_index) {
-  size_t first_block_in_chunk = chunk_index * BlocksPerChunk;
-  size_t last_block_in_chunk = (chunk_index + 1) * BlocksPerChunk - 1;
-
-  return (first_block_in_chunk <= block_index) &&
-         (block_index <= last_block_in_chunk);
+bool ParallelCompactData::region_contains_block(size_t region_index,
+                                                size_t block_index) {
+  size_t first_block_in_region = region_index * BlocksPerRegion;
+  size_t last_block_in_region = (region_index + 1) * BlocksPerRegion - 1;
+
+  return (first_block_in_region <= block_index) &&
+         (block_index <= last_block_in_region);
 }
 
 // This method contains no policy. You should probably
@@ -2205,7 +2213,7 @@
 
   ParallelScavengeHeap* heap = gc_heap();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
-  TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();
+  TaskQueueSetSuper* qset = ParCompactionManager::region_array();
   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
 
   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
@@ -2343,8 +2351,9 @@
   move_and_update(cm, perm_space_id);
 }
 
-void PSParallelCompact::enqueue_chunk_draining_tasks(GCTaskQueue* q,
-                                                     uint parallel_gc_threads) {
+void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
+                                                      uint parallel_gc_threads)
+{
   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
 
   const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
@@ -2352,13 +2361,13 @@
     q->enqueue(new DrainStacksCompactionTask());
   }
 
-  // Find all chunks that are available (can be filled immediately) and
+  // Find all regions that are available (can be filled immediately) and
   // distribute them to the thread stacks.  The iteration is done in reverse
-  // order (high to low) so the chunks will be removed in ascending order.
+  // order (high to low) so the regions will be removed in ascending order.
 
   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 
-  size_t fillable_chunks = 0;   // A count for diagnostic purposes.
+  size_t fillable_regions = 0;   // A count for diagnostic purposes.
   unsigned int which = 0;       // The worker thread number.
 
   for (unsigned int id = to_space_id; id > perm_space_id; --id) {
@@ -2366,25 +2375,26 @@
     MutableSpace* const space = space_info->space();
     HeapWord* const new_top = space_info->new_top();
 
-    const size_t beg_chunk = sd.addr_to_chunk_idx(space_info->dense_prefix());
-    const size_t end_chunk = sd.addr_to_chunk_idx(sd.chunk_align_up(new_top));
-    assert(end_chunk > 0, "perm gen cannot be empty");
-
-    for (size_t cur = end_chunk - 1; cur >= beg_chunk; --cur) {
-      if (sd.chunk(cur)->claim_unsafe()) {
+    const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
+    const size_t end_region =
+      sd.addr_to_region_idx(sd.region_align_up(new_top));
+    assert(end_region > 0, "perm gen cannot be empty");
+
+    for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
+      if (sd.region(cur)->claim_unsafe()) {
         ParCompactionManager* cm = ParCompactionManager::manager_array(which);
         cm->save_for_processing(cur);
 
         if (TraceParallelOldGCCompactionPhase && Verbose) {
-          const size_t count_mod_8 = fillable_chunks & 7;
+          const size_t count_mod_8 = fillable_regions & 7;
           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
           if (count_mod_8 == 7) gclog_or_tty->cr();
         }
 
-        NOT_PRODUCT(++fillable_chunks;)
-
-        // Assign chunks to threads in round-robin fashion.
+        NOT_PRODUCT(++fillable_regions;)
+
+        // Assign regions to threads in round-robin fashion.
         if (++which == task_count) {
           which = 0;
         }
@@ -2393,8 +2403,8 @@
   }
 
   if (TraceParallelOldGCCompactionPhase) {
-    if (Verbose && (fillable_chunks & 7) != 0) gclog_or_tty->cr();
-    gclog_or_tty->print_cr("%u initially fillable chunks", fillable_chunks);
+    if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
+    gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
   }
 }
 
@@ -2407,7 +2417,7 @@
   ParallelCompactData& sd = PSParallelCompact::summary_data();
 
   // Iterate over all the spaces adding tasks for updating
-  // chunks in the dense prefix.  Assume that 1 gc thread
+  // regions in the dense prefix.  Assume that 1 gc thread
   // will work on opening the gaps and the remaining gc threads
   // will work on the dense prefix.
   SpaceId space_id = old_space_id;
@@ -2421,30 +2431,31 @@
       continue;
     }
 
-    // The dense prefix is before this chunk.
-    size_t chunk_index_end_dense_prefix =
-        sd.addr_to_chunk_idx(dense_prefix_end);
-    ChunkData* const dense_prefix_cp = sd.chunk(chunk_index_end_dense_prefix);
+    // The dense prefix is before this region.
+    size_t region_index_end_dense_prefix =
+        sd.addr_to_region_idx(dense_prefix_end);
+    RegionData* const dense_prefix_cp =
+      sd.region(region_index_end_dense_prefix);
     assert(dense_prefix_end == space->end() ||
            dense_prefix_cp->available() ||
            dense_prefix_cp->claimed(),
-           "The chunk after the dense prefix should always be ready to fill");
-
-    size_t chunk_index_start = sd.addr_to_chunk_idx(space->bottom());
+           "The region after the dense prefix should always be ready to fill");
+
+    size_t region_index_start = sd.addr_to_region_idx(space->bottom());
 
     // Is there dense prefix work?
-    size_t total_dense_prefix_chunks =
-      chunk_index_end_dense_prefix - chunk_index_start;
-    // How many chunks of the dense prefix should be given to
+    size_t total_dense_prefix_regions =
+      region_index_end_dense_prefix - region_index_start;
+    // How many regions of the dense prefix should be given to
     // each thread?
-    if (total_dense_prefix_chunks > 0) {
+    if (total_dense_prefix_regions > 0) {
       uint tasks_for_dense_prefix = 1;
       if (UseParallelDensePrefixUpdate) {
-        if (total_dense_prefix_chunks <=
+        if (total_dense_prefix_regions <=
             (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
           // Don't over partition.  This assumes that
           // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
-          // so there are not many chunks to process.
+          // so there are not many regions to process.
           tasks_for_dense_prefix = parallel_gc_threads;
         } else {
           // Over partition
@@ -2452,50 +2463,50 @@
             PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
         }
       }
-      size_t chunks_per_thread = total_dense_prefix_chunks /
+      size_t regions_per_thread = total_dense_prefix_regions /
         tasks_for_dense_prefix;
-      // Give each thread at least 1 chunk.
-      if (chunks_per_thread == 0) {
-        chunks_per_thread = 1;
+      // Give each thread at least 1 region.
+      if (regions_per_thread == 0) {
+        regions_per_thread = 1;
       }
 
       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
-        if (chunk_index_start >= chunk_index_end_dense_prefix) {
+        if (region_index_start >= region_index_end_dense_prefix) {
           break;
         }
-        // chunk_index_end is not processed
-        size_t chunk_index_end = MIN2(chunk_index_start + chunks_per_thread,
-                                      chunk_index_end_dense_prefix);
+        // region_index_end is not processed
+        size_t region_index_end = MIN2(region_index_start + regions_per_thread,
+                                       region_index_end_dense_prefix);
         q->enqueue(new UpdateDensePrefixTask(
                                  space_id,
-                                 chunk_index_start,
-                                 chunk_index_end));
-        chunk_index_start = chunk_index_end;
+                                 region_index_start,
+                                 region_index_end));
+        region_index_start = region_index_end;
       }
     }
     // This gets any part of the dense prefix that did not
     // fit evenly.
-    if (chunk_index_start < chunk_index_end_dense_prefix) {
+    if (region_index_start < region_index_end_dense_prefix) {
       q->enqueue(new UpdateDensePrefixTask(
                                  space_id,
-                                 chunk_index_start,
-                                 chunk_index_end_dense_prefix));
+                                 region_index_start,
+                                 region_index_end_dense_prefix));
     }
     space_id = next_compaction_space_id(space_id);
   }  // End tasks for dense prefix
 }
 
-void PSParallelCompact::enqueue_chunk_stealing_tasks(
+void PSParallelCompact::enqueue_region_stealing_tasks(
                                      GCTaskQueue* q,
                                      ParallelTaskTerminator* terminator_ptr,
                                      uint parallel_gc_threads) {
   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
 
-  // Once a thread has drained it's stack, it should try to steal chunks from
+  // Once a thread has drained it's stack, it should try to steal regions from
   // other threads.
   if (parallel_gc_threads > 1) {
     for (uint j = 0; j < parallel_gc_threads; j++) {
-      q->enqueue(new StealChunkCompactionTask(terminator_ptr));
+      q->enqueue(new StealRegionCompactionTask(terminator_ptr));
     }
   }
 }
@@ -2510,13 +2521,13 @@
   PSOldGen* old_gen = heap->old_gen();
   old_gen->start_array()->reset();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
-  TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();
+  TaskQueueSetSuper* qset = ParCompactionManager::region_array();
   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
 
   GCTaskQueue* q = GCTaskQueue::create();
-  enqueue_chunk_draining_tasks(q, parallel_gc_threads);
+  enqueue_region_draining_tasks(q, parallel_gc_threads);
   enqueue_dense_prefix_tasks(q, parallel_gc_threads);
-  enqueue_chunk_stealing_tasks(q, &terminator, parallel_gc_threads);
+  enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
 
   {
     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
@@ -2532,9 +2543,9 @@
     WaitForBarrierGCTask::destroy(fin);
 
 #ifdef  ASSERT
-    // Verify that all chunks have been processed before the deferred updates.
+    // Verify that all regions have been processed before the deferred updates.
     // Note that perm_space_id is skipped; this type of verification is not
-    // valid until the perm gen is compacted by chunks.
+    // valid until the perm gen is compacted by regions.
     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
       verify_complete(SpaceId(id));
     }
@@ -2553,42 +2564,42 @@
 
 #ifdef  ASSERT
 void PSParallelCompact::verify_complete(SpaceId space_id) {
-  // All Chunks between space bottom() to new_top() should be marked as filled
-  // and all Chunks between new_top() and top() should be available (i.e.,
+  // All Regions between space bottom() to new_top() should be marked as filled
+  // and all Regions between new_top() and top() should be available (i.e.,
   // should have been emptied).
   ParallelCompactData& sd = summary_data();
   SpaceInfo si = _space_info[space_id];
-  HeapWord* new_top_addr = sd.chunk_align_up(si.new_top());
-  HeapWord* old_top_addr = sd.chunk_align_up(si.space()->top());
-  const size_t beg_chunk = sd.addr_to_chunk_idx(si.space()->bottom());
-  const size_t new_top_chunk = sd.addr_to_chunk_idx(new_top_addr);
-  const size_t old_top_chunk = sd.addr_to_chunk_idx(old_top_addr);
+  HeapWord* new_top_addr = sd.region_align_up(si.new_top());
+  HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
+  const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
+  const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
+  const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
 
   bool issued_a_warning = false;
 
-  size_t cur_chunk;
-  for (cur_chunk = beg_chunk; cur_chunk < new_top_chunk; ++cur_chunk) {
-    const ChunkData* const c = sd.chunk(cur_chunk);
+  size_t cur_region;
+  for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
+    const RegionData* const c = sd.region(cur_region);
     if (!c->completed()) {
-      warning("chunk " SIZE_FORMAT " not filled:  "
+      warning("region " SIZE_FORMAT " not filled:  "
               "destination_count=" SIZE_FORMAT,
-              cur_chunk, c->destination_count());
+              cur_region, c->destination_count());
       issued_a_warning = true;
     }
   }
 
-  for (cur_chunk = new_top_chunk; cur_chunk < old_top_chunk; ++cur_chunk) {
-    const ChunkData* const c = sd.chunk(cur_chunk);
+  for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
+    const RegionData* const c = sd.region(cur_region);
     if (!c->available()) {
-      warning("chunk " SIZE_FORMAT " not empty:   "
+      warning("region " SIZE_FORMAT " not empty:   "
               "destination_count=" SIZE_FORMAT,
-              cur_chunk, c->destination_count());
+              cur_region, c->destination_count());
       issued_a_warning = true;
     }
   }
 
   if (issued_a_warning) {
-    print_chunk_ranges();
+    print_region_ranges();
   }
 }
 #endif  // #ifdef ASSERT
@@ -2789,46 +2800,47 @@
 }
 #endif //VALIDATE_MARK_SWEEP
 
-// Update interior oops in the ranges of chunks [beg_chunk, end_chunk).
+// Update interior oops in the ranges of regions [beg_region, end_region).
 void
 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
                                                        SpaceId space_id,
-                                                       size_t beg_chunk,
-                                                       size_t end_chunk) {
+                                                       size_t beg_region,
+                                                       size_t end_region) {
   ParallelCompactData& sd = summary_data();
   ParMarkBitMap* const mbm = mark_bitmap();
 
-  HeapWord* beg_addr = sd.chunk_to_addr(beg_chunk);
-  HeapWord* const end_addr = sd.chunk_to_addr(end_chunk);
-  assert(beg_chunk <= end_chunk, "bad chunk range");
+  HeapWord* beg_addr = sd.region_to_addr(beg_region);
+  HeapWord* const end_addr = sd.region_to_addr(end_region);
+  assert(beg_region <= end_region, "bad region range");
   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
 
 #ifdef  ASSERT
-  // Claim the chunks to avoid triggering an assert when they are marked as
+  // Claim the regions to avoid triggering an assert when they are marked as
   // filled.
-  for (size_t claim_chunk = beg_chunk; claim_chunk < end_chunk; ++claim_chunk) {
-    assert(sd.chunk(claim_chunk)->claim_unsafe(), "claim() failed");
+  for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
+    assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
   }
 #endif  // #ifdef ASSERT
 
   if (beg_addr != space(space_id)->bottom()) {
     // Find the first live object or block of dead space that *starts* in this
-    // range of chunks.  If a partial object crosses onto the chunk, skip it; it
-    // will be marked for 'deferred update' when the object head is processed.
-    // If dead space crosses onto the chunk, it is also skipped; it will be
-    // filled when the prior chunk is processed.  If neither of those apply, the
-    // first word in the chunk is the start of a live object or dead space.
+    // range of regions.  If a partial object crosses onto the region, skip it;
+    // it will be marked for 'deferred update' when the object head is
+    // processed.  If dead space crosses onto the region, it is also skipped; it
+    // will be filled when the prior region is processed.  If neither of those
+    // apply, the first word in the region is the start of a live object or dead
+    // space.
     assert(beg_addr > space(space_id)->bottom(), "sanity");
-    const ChunkData* const cp = sd.chunk(beg_chunk);
+    const RegionData* const cp = sd.region(beg_region);
     if (cp->partial_obj_size() != 0) {
-      beg_addr = sd.partial_obj_end(beg_chunk);
+      beg_addr = sd.partial_obj_end(beg_region);
     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
     }
   }
 
   if (beg_addr < end_addr) {
-    // A live object or block of dead space starts in this range of Chunks.
+    // A live object or block of dead space starts in this range of Regions.
      HeapWord* const dense_prefix_end = dense_prefix(space_id);
 
     // Create closures and iterate.
@@ -2842,10 +2854,10 @@
     }
   }
 
-  // Mark the chunks as filled.
-  ChunkData* const beg_cp = sd.chunk(beg_chunk);
-  ChunkData* const end_cp = sd.chunk(end_chunk);
-  for (ChunkData* cp = beg_cp; cp < end_cp; ++cp) {
+  // Mark the regions as filled.
+  RegionData* const beg_cp = sd.region(beg_region);
+  RegionData* const end_cp = sd.region(end_region);
+  for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
     cp->set_completed();
   }
 }
@@ -2877,13 +2889,13 @@
   const MutableSpace* const space = space_info->space();
   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
   HeapWord* const beg_addr = space_info->dense_prefix();
-  HeapWord* const end_addr = sd.chunk_align_up(space_info->new_top());
-
-  const ChunkData* const beg_chunk = sd.addr_to_chunk_ptr(beg_addr);
-  const ChunkData* const end_chunk = sd.addr_to_chunk_ptr(end_addr);
-  const ChunkData* cur_chunk;
-  for (cur_chunk = beg_chunk; cur_chunk < end_chunk; ++cur_chunk) {
-    HeapWord* const addr = cur_chunk->deferred_obj_addr();
+  HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
+
+  const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
+  const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
+  const RegionData* cur_region;
+  for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
+    HeapWord* const addr = cur_region->deferred_obj_addr();
     if (addr != NULL) {
       if (start_array != NULL) {
         start_array->allocate_block(addr);
@@ -2929,45 +2941,45 @@
 
 HeapWord*
 PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
-                                 size_t src_chunk_idx)
+                                 size_t src_region_idx)
 {
   ParMarkBitMap* const bitmap = mark_bitmap();
   const ParallelCompactData& sd = summary_data();
-  const size_t ChunkSize = ParallelCompactData::ChunkSize;
-
-  assert(sd.is_chunk_aligned(dest_addr), "not aligned");
-
-  const ChunkData* const src_chunk_ptr = sd.chunk(src_chunk_idx);
-  const size_t partial_obj_size = src_chunk_ptr->partial_obj_size();
-  HeapWord* const src_chunk_destination = src_chunk_ptr->destination();
-
-  assert(dest_addr >= src_chunk_destination, "wrong src chunk");
-  assert(src_chunk_ptr->data_size() > 0, "src chunk cannot be empty");
-
-  HeapWord* const src_chunk_beg = sd.chunk_to_addr(src_chunk_idx);
-  HeapWord* const src_chunk_end = src_chunk_beg + ChunkSize;
-
-  HeapWord* addr = src_chunk_beg;
-  if (dest_addr == src_chunk_destination) {
-    // Return the first live word in the source chunk.
+  const size_t RegionSize = ParallelCompactData::RegionSize;
+
+  assert(sd.is_region_aligned(dest_addr), "not aligned");
+
+  const RegionData* const src_region_ptr = sd.region(src_region_idx);
+  const size_t partial_obj_size = src_region_ptr->partial_obj_size();
+  HeapWord* const src_region_destination = src_region_ptr->destination();
+
+  assert(dest_addr >= src_region_destination, "wrong src region");
+  assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
+
+  HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
+  HeapWord* const src_region_end = src_region_beg + RegionSize;
+
+  HeapWord* addr = src_region_beg;
+  if (dest_addr == src_region_destination) {
+    // Return the first live word in the source region.
     if (partial_obj_size == 0) {
-      addr = bitmap->find_obj_beg(addr, src_chunk_end);
-      assert(addr < src_chunk_end, "no objects start in src chunk");
+      addr = bitmap->find_obj_beg(addr, src_region_end);
+      assert(addr < src_region_end, "no objects start in src region");
     }
     return addr;
   }
 
   // Must skip some live data.
-  size_t words_to_skip = dest_addr - src_chunk_destination;
-  assert(src_chunk_ptr->data_size() > words_to_skip, "wrong src chunk");
+  size_t words_to_skip = dest_addr - src_region_destination;
+  assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
 
   if (partial_obj_size >= words_to_skip) {
     // All the live words to skip are part of the partial object.
     addr += words_to_skip;
     if (partial_obj_size == words_to_skip) {
       // Find the first live word past the partial object.
-      addr = bitmap->find_obj_beg(addr, src_chunk_end);
-      assert(addr < src_chunk_end, "wrong src chunk");
+      addr = bitmap->find_obj_beg(addr, src_region_end);
+      assert(addr < src_region_end, "wrong src region");
     }
     return addr;
   }
@@ -2978,63 +2990,64 @@
     addr += partial_obj_size;
   }
 
-  // Skip over live words due to objects that start in the chunk.
-  addr = skip_live_words(addr, src_chunk_end, words_to_skip);
-  assert(addr < src_chunk_end, "wrong src chunk");
+  // Skip over live words due to objects that start in the region.
+  addr = skip_live_words(addr, src_region_end, words_to_skip);
+  assert(addr < src_region_end, "wrong src region");
   return addr;
 }
 
 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
-                                                     size_t beg_chunk,
+                                                     size_t beg_region,
                                                      HeapWord* end_addr)
 {
   ParallelCompactData& sd = summary_data();
-  ChunkData* const beg = sd.chunk(beg_chunk);
-  HeapWord* const end_addr_aligned_up = sd.chunk_align_up(end_addr);
-  ChunkData* const end = sd.addr_to_chunk_ptr(end_addr_aligned_up);
-  size_t cur_idx = beg_chunk;
-  for (ChunkData* cur = beg; cur < end; ++cur, ++cur_idx) {
-    assert(cur->data_size() > 0, "chunk must have live data");
+  RegionData* const beg = sd.region(beg_region);
+  HeapWord* const end_addr_aligned_up = sd.region_align_up(end_addr);
+  RegionData* const end = sd.addr_to_region_ptr(end_addr_aligned_up);
+  size_t cur_idx = beg_region;
+  for (RegionData* cur = beg; cur < end; ++cur, ++cur_idx) {
+    assert(cur->data_size() > 0, "region must have live data");
     cur->decrement_destination_count();
-    if (cur_idx <= cur->source_chunk() && cur->available() && cur->claim()) {
+    if (cur_idx <= cur->source_region() && cur->available() && cur->claim()) {
       cm->save_for_processing(cur_idx);
     }
   }
 }
 
-size_t PSParallelCompact::next_src_chunk(MoveAndUpdateClosure& closure,
-                                         SpaceId& src_space_id,
-                                         HeapWord*& src_space_top,
-                                         HeapWord* end_addr)
+size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
+                                          SpaceId& src_space_id,
+                                          HeapWord*& src_space_top,
+                                          HeapWord* end_addr)
 {
-  typedef ParallelCompactData::ChunkData ChunkData;
+  typedef ParallelCompactData::RegionData RegionData;
 
   ParallelCompactData& sd = PSParallelCompact::summary_data();
-  const size_t chunk_size = ParallelCompactData::ChunkSize;
-
-  size_t src_chunk_idx = 0;
-
-  // Skip empty chunks (if any) up to the top of the space.
-  HeapWord* const src_aligned_up = sd.chunk_align_up(end_addr);
-  ChunkData* src_chunk_ptr = sd.addr_to_chunk_ptr(src_aligned_up);
-  HeapWord* const top_aligned_up = sd.chunk_align_up(src_space_top);
-  const ChunkData* const top_chunk_ptr = sd.addr_to_chunk_ptr(top_aligned_up);
-  while (src_chunk_ptr < top_chunk_ptr && src_chunk_ptr->data_size() == 0) {
-    ++src_chunk_ptr;
+  const size_t region_size = ParallelCompactData::RegionSize;
+
+  size_t src_region_idx = 0;
+
+  // Skip empty regions (if any) up to the top of the space.
+  HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
+  RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
+  HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
+  const RegionData* const top_region_ptr =
+    sd.addr_to_region_ptr(top_aligned_up);
+  while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
+    ++src_region_ptr;
   }
 
-  if (src_chunk_ptr < top_chunk_ptr) {
-    // The next source chunk is in the current space.  Update src_chunk_idx and
-    // the source address to match src_chunk_ptr.
-    src_chunk_idx = sd.chunk(src_chunk_ptr);
-    HeapWord* const src_chunk_addr = sd.chunk_to_addr(src_chunk_idx);
-    if (src_chunk_addr > closure.source()) {
-      closure.set_source(src_chunk_addr);
+  if (src_region_ptr < top_region_ptr) {
+    // The next source region is in the current space.  Update src_region_idx
+    // and the source address to match src_region_ptr.
+    src_region_idx = sd.region(src_region_ptr);
+    HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
+    if (src_region_addr > closure.source()) {
+      closure.set_source(src_region_addr);
     }
-    return src_chunk_idx;
+    return src_region_idx;
   }
 
-  // Switch to a new source space and find the first non-empty chunk.
+  // Switch to a new source space and find the first non-empty region.
   unsigned int space_id = src_space_id + 1;
   assert(space_id < last_space_id, "not enough spaces");
 
@@ -3043,14 +3056,14 @@
   do {
     MutableSpace* space = _space_info[space_id].space();
     HeapWord* const bottom = space->bottom();
-    const ChunkData* const bottom_cp = sd.addr_to_chunk_ptr(bottom);
+    const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
 
     // Iterate over the spaces that do not compact into themselves.
     if (bottom_cp->destination() != bottom) {
-      HeapWord* const top_aligned_up = sd.chunk_align_up(space->top());
-      const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up);
-
-      for (const ChunkData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
+      HeapWord* const top_aligned_up = sd.region_align_up(space->top());
+      const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
+
+      for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
         if (src_cp->live_obj_size() > 0) {
           // Found it.
           assert(src_cp->destination() == destination,
@@ -3060,9 +3073,9 @@
 
           src_space_id = SpaceId(space_id);
           src_space_top = space->top();
-          const size_t src_chunk_idx = sd.chunk(src_cp);
-          closure.set_source(sd.chunk_to_addr(src_chunk_idx));
-          return src_chunk_idx;
+          const size_t src_region_idx = sd.region(src_cp);
+          closure.set_source(sd.region_to_addr(src_region_idx));
+          return src_region_idx;
         } else {
           assert(src_cp->data_size() == 0, "sanity");
         }
@@ -3070,38 +3083,38 @@
     }
   } while (++space_id < last_space_id);
 
-  assert(false, "no source chunk was found");
+  assert(false, "no source region was found");
   return 0;
 }
 
-void PSParallelCompact::fill_chunk(ParCompactionManager* cm, size_t chunk_idx)
+void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
 {
   typedef ParMarkBitMap::IterationStatus IterationStatus;
-  const size_t ChunkSize = ParallelCompactData::ChunkSize;
+  const size_t RegionSize = ParallelCompactData::RegionSize;
   ParMarkBitMap* const bitmap = mark_bitmap();
   ParallelCompactData& sd = summary_data();
-  ChunkData* const chunk_ptr = sd.chunk(chunk_idx);
+  RegionData* const region_ptr = sd.region(region_idx);
 
   // Get the items needed to construct the closure.
-  HeapWord* dest_addr = sd.chunk_to_addr(chunk_idx);
+  HeapWord* dest_addr = sd.region_to_addr(region_idx);
   SpaceId dest_space_id = space_id(dest_addr);
   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
   HeapWord* new_top = _space_info[dest_space_id].new_top();
   assert(dest_addr < new_top, "sanity");
-  const size_t words = MIN2(pointer_delta(new_top, dest_addr), ChunkSize);
-
-  // Get the source chunk and related info.
-  size_t src_chunk_idx = chunk_ptr->source_chunk();
-  SpaceId src_space_id = space_id(sd.chunk_to_addr(src_chunk_idx));
+  const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
+
+  // Get the source region and related info.
+  size_t src_region_idx = region_ptr->source_region();
+  SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
 
   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
-  closure.set_source(first_src_addr(dest_addr, src_chunk_idx));
-
-  // Adjust src_chunk_idx to prepare for decrementing destination counts (the
-  // destination count is not decremented when a chunk is copied to itself).
-  if (src_chunk_idx == chunk_idx) {
-    src_chunk_idx += 1;
+  closure.set_source(first_src_addr(dest_addr, src_region_idx));
+
+  // Adjust src_region_idx to prepare for decrementing destination counts (the
+  // destination count is not decremented when a region is copied to itself).
+  if (src_region_idx == region_idx) {
+    src_region_idx += 1;
   }
 
   if (bitmap->is_unmarked(closure.source())) {
@@ -3111,32 +3124,33 @@
     HeapWord* const old_src_addr = closure.source();
     closure.copy_partial_obj();
     if (closure.is_full()) {
-      decrement_destination_counts(cm, src_chunk_idx, closure.source());
-      chunk_ptr->set_deferred_obj_addr(NULL);
-      chunk_ptr->set_completed();
+      decrement_destination_counts(cm, src_region_idx, closure.source());
+      region_ptr->set_deferred_obj_addr(NULL);
+      region_ptr->set_completed();
       return;
     }
 
-    HeapWord* const end_addr = sd.chunk_align_down(closure.source());
-    if (sd.chunk_align_down(old_src_addr) != end_addr) {
-      // The partial object was copied from more than one source chunk.
-      decrement_destination_counts(cm, src_chunk_idx, end_addr);
-
-      // Move to the next source chunk, possibly switching spaces as well.  All
+    HeapWord* const end_addr = sd.region_align_down(closure.source());
+    if (sd.region_align_down(old_src_addr) != end_addr) {
+      // The partial object was copied from more than one source region.
+      decrement_destination_counts(cm, src_region_idx, end_addr);
+
+      // Move to the next source region, possibly switching spaces as well.  All
       // args except end_addr may be modified.
-      src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top,
-                                     end_addr);
+      src_region_idx = next_src_region(closure, src_space_id, src_space_top,
+                                       end_addr);
     }
   }
 
   do {
     HeapWord* const cur_addr = closure.source();
-    HeapWord* const end_addr = MIN2(sd.chunk_align_up(cur_addr + 1),
+    HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
                                     src_space_top);
     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
 
     if (status == ParMarkBitMap::incomplete) {
-      // The last obj that starts in the source chunk does not end in the chunk.
+      // The last obj that starts in the source region does not end in the
+      // region.
       assert(closure.source() < end_addr, "sanity")
       HeapWord* const obj_beg = closure.source();
       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
@@ -3155,28 +3169,28 @@
 
     if (status == ParMarkBitMap::would_overflow) {
       // The last object did not fit.  Note that interior oop updates were
-      // deferred, then copy enough of the object to fill the chunk.
-      chunk_ptr->set_deferred_obj_addr(closure.destination());
+      // deferred, then copy enough of the object to fill the region.
+      region_ptr->set_deferred_obj_addr(closure.destination());
       status = closure.copy_until_full(); // copies from closure.source()
 
-      decrement_destination_counts(cm, src_chunk_idx, closure.source());
-      chunk_ptr->set_completed();
+      decrement_destination_counts(cm, src_region_idx, closure.source());
+      region_ptr->set_completed();
       return;
     }
 
     if (status == ParMarkBitMap::full) {
-      decrement_destination_counts(cm, src_chunk_idx, closure.source());
-      chunk_ptr->set_deferred_obj_addr(NULL);
-      chunk_ptr->set_completed();
+      decrement_destination_counts(cm, src_region_idx, closure.source());
+      region_ptr->set_deferred_obj_addr(NULL);
+      region_ptr->set_completed();
       return;
     }
 
-    decrement_destination_counts(cm, src_chunk_idx, end_addr);
-
-    // Move to the next source chunk, possibly switching spaces as well.  All
+    decrement_destination_counts(cm, src_region_idx, end_addr);
+
+    // Move to the next source region, possibly switching spaces as well.  All
     // args except end_addr may be modified.
-    src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top,
-                                   end_addr);
+    src_region_idx = next_src_region(closure, src_space_id, src_space_top,
+                                     end_addr);
   } while (true);
 }
 
@@ -3208,15 +3222,15 @@
   }
 #endif
 
-  const size_t beg_chunk = sd.addr_to_chunk_idx(beg_addr);
-  const size_t dp_chunk = sd.addr_to_chunk_idx(dp_addr);
-  if (beg_chunk < dp_chunk) {
-    update_and_deadwood_in_dense_prefix(cm, space_id, beg_chunk, dp_chunk);
+  const size_t beg_region = sd.addr_to_region_idx(beg_addr);
+  const size_t dp_region = sd.addr_to_region_idx(dp_addr);
+  if (beg_region < dp_region) {
+    update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
   }
 
-  // The destination of the first live object that starts in the chunk is one
-  // past the end of the partial object entering the chunk (if any).
-  HeapWord* const dest_addr = sd.partial_obj_end(dp_chunk);
+  // The destination of the first live object that starts in the region is one
+  // past the end of the partial object entering the region (if any).
+  HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
   HeapWord* const new_top = _space_info[space_id].new_top();
   assert(new_top >= dest_addr, "bad new_top value");
   const size_t words = pointer_delta(new_top, dest_addr);
@@ -3327,41 +3341,41 @@
 
 BitBlockUpdateClosure::BitBlockUpdateClosure(ParMarkBitMap* mbm,
                         ParCompactionManager* cm,
-                        size_t chunk_index) :
+                        size_t region_index) :
                         ParMarkBitMapClosure(mbm, cm),
                         _live_data_left(0),
                         _cur_block(0) {
-  _chunk_start =
-    PSParallelCompact::summary_data().chunk_to_addr(chunk_index);
-  _chunk_end =
-    PSParallelCompact::summary_data().chunk_to_addr(chunk_index) +
-                 ParallelCompactData::ChunkSize;
-  _chunk_index = chunk_index;
+  _region_start =
+    PSParallelCompact::summary_data().region_to_addr(region_index);
+  _region_end =
+    PSParallelCompact::summary_data().region_to_addr(region_index) +
+                 ParallelCompactData::RegionSize;
+  _region_index = region_index;
   _cur_block =
-    PSParallelCompact::summary_data().addr_to_block_idx(_chunk_start);
+    PSParallelCompact::summary_data().addr_to_block_idx(_region_start);
 }
 
-bool BitBlockUpdateClosure::chunk_contains_cur_block() {
-  return ParallelCompactData::chunk_contains_block(_chunk_index, _cur_block);
+bool BitBlockUpdateClosure::region_contains_cur_block() {
+  return ParallelCompactData::region_contains_block(_region_index, _cur_block);
 }
 
-void BitBlockUpdateClosure::reset_chunk(size_t chunk_index) {
+void BitBlockUpdateClosure::reset_region(size_t region_index) {
   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(7);)
   ParallelCompactData& sd = PSParallelCompact::summary_data();
-  _chunk_index = chunk_index;
+  _region_index = region_index;
   _live_data_left = 0;
-  _chunk_start = sd.chunk_to_addr(chunk_index);
-  _chunk_end = sd.chunk_to_addr(chunk_index) + ParallelCompactData::ChunkSize;
-
-  // The first block in this chunk
-  size_t first_block =  sd.addr_to_block_idx(_chunk_start);
-  size_t partial_live_size = sd.chunk(chunk_index)->partial_obj_size();
+  _region_start = sd.region_to_addr(region_index);
+  _region_end = sd.region_to_addr(region_index) + ParallelCompactData::RegionSize;
+
+  // The first block in this region
+  size_t first_block =  sd.addr_to_block_idx(_region_start);
+  size_t partial_live_size = sd.region(region_index)->partial_obj_size();
 
   // Set the offset to 0. By definition it should have that value
-  // but it may have been written while processing an earlier chunk.
+  // but it may have been written while processing an earlier region.
   if (partial_live_size == 0) {
-    // No live object extends onto the chunk.  The first bit
-    // in the bit map for the first chunk must be a start bit.
+    // No live object extends onto the region.  The first bit
+    // in the bit map for the first region must be a start bit.
     // Although there may not be any marked bits, it is safe
     // to set it as a start bit.
     sd.block(first_block)->set_start_bit_offset(0);
@@ -3413,8 +3427,8 @@
   ParallelCompactData& sd = PSParallelCompact::summary_data();
 
   assert(bitmap()->obj_size(obj) == words, "bad size");
-  assert(_chunk_start <= obj, "object is not in chunk");
-  assert(obj + words <= _chunk_end, "object is not in chunk");
+  assert(_region_start <= obj, "object is not in region");
+  assert(obj + words <= _region_end, "object is not in region");
 
   // Update the live data to the left
   size_t prev_live_data_left = _live_data_left;
@@ -3432,7 +3446,7 @@
     // the new block with the data size that does not include this object.
     //
     // The first bit in block_of_obj is a start bit except in the
-    // case where the partial object for the chunk extends into
+    // case where the partial object for the region extends into
     // this block.
     if (sd.partial_obj_ends_in_block(block_of_obj)) {
       sd.block(block_of_obj)->set_end_bit_offset(prev_live_data_left);
@@ -3449,9 +3463,9 @@
       // The offset for blocks with no objects starting in them
       // (e.g., blocks between _cur_block and  block_of_obj_last)
       // should not be needed.
-      // Note that block_of_obj_last may be in another chunk.  If so,
+      // Note that block_of_obj_last may be in another region.  If so,
       // it should be overwritten later.  This is a problem (writting
-      // into a block in a later chunk) for parallel execution.
+      // into a block in a later region) for parallel execution.
       assert(obj < block_of_obj_last_addr,
         "Object should start in previous block");
 
@@ -3485,7 +3499,7 @@
   }
 
   // Return incomplete if there are more blocks to be done.
-  if (chunk_contains_cur_block()) {
+  if (region_contains_cur_block()) {
     return ParMarkBitMap::incomplete;
   }
   return ParMarkBitMap::complete;
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp
--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Tue Sep 30 12:20:22 2008 -0700
@@ -76,87 +76,87 @@
 {
 public:
   // Sizes are in HeapWords, unless indicated otherwise.
-  static const size_t Log2ChunkSize;
-  static const size_t ChunkSize;
-  static const size_t ChunkSizeBytes;
+  static const size_t Log2RegionSize;
+  static const size_t RegionSize;
+  static const size_t RegionSizeBytes;
 
-  // Mask for the bits in a size_t to get an offset within a chunk.
-  static const size_t ChunkSizeOffsetMask;
-  // Mask for the bits in a pointer to get an offset within a chunk.
-  static const size_t ChunkAddrOffsetMask;
-  // Mask for the bits in a pointer to get the address of the start of a chunk.
-  static const size_t ChunkAddrMask;
+  // Mask for the bits in a size_t to get an offset within a region.
+  static const size_t RegionSizeOffsetMask;
+  // Mask for the bits in a pointer to get an offset within a region.
+  static const size_t RegionAddrOffsetMask;
+  // Mask for the bits in a pointer to get the address of the start of a region.
+  static const size_t RegionAddrMask;
 
   static const size_t Log2BlockSize;
   static const size_t BlockSize;
   static const size_t BlockOffsetMask;
   static const size_t BlockMask;
 
-  static const size_t BlocksPerChunk;
+  static const size_t BlocksPerRegion;
 
-  class ChunkData
+  class RegionData
   {
   public:
-    // Destination address of the chunk.
+    // Destination address of the region.
     HeapWord* destination() const { return _destination; }
 
-    // The first chunk containing data destined for this chunk.
-    size_t source_chunk() const { return _source_chunk; }
+    // The first region containing data destined for this region.
+    size_t source_region() const { return _source_region; }
 
-    // The object (if any) starting in this chunk and ending in a different
-    // chunk that could not be updated during the main (parallel) compaction
+    // The object (if any) starting in this region and ending in a different
+    // region that could not be updated during the main (parallel) compaction
     // phase.  This is different from _partial_obj_addr, which is an object that
-    // extends onto a source chunk.  However, the two uses do not overlap in
+    // extends onto a source region.  However, the two uses do not overlap in
     // time, so the same field is used to save space.
     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
 
-    // The starting address of the partial object extending onto the chunk.
+    // The starting address of the partial object extending onto the region.
     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
 
-    // Size of the partial object extending onto the chunk (words).
+    // Size of the partial object extending onto the region (words).
     size_t partial_obj_size() const { return _partial_obj_size; }
 
-    // Size of live data that lies within this chunk due to objects that start
-    // in this chunk (words).  This does not include the partial object
-    // extending onto the chunk (if any), or the part of an object that extends
-    // onto the next chunk (if any).
+    // Size of live data that lies within this region due to objects that start
+    // in this region (words).  This does not include the partial object
+    // extending onto the region (if any), or the part of an object that extends
+    // onto the next region (if any).
     size_t live_obj_size() const { return _dc_and_los & los_mask; }
 
-    // Total live data that lies within the chunk (words).
+    // Total live data that lies within the region (words).
     size_t data_size() const { return partial_obj_size() + live_obj_size(); }
 
-    // The destination_count is the number of other chunks to which data from
-    // this chunk will be copied.  At the end of the summary phase, the valid
+    // The destination_count is the number of other regions to which data from
+    // this region will be copied.  At the end of the summary phase, the valid
     // values of destination_count are
     //
-    // 0 - data from the chunk will be compacted completely into itself, or the
-    //     chunk is empty.  The chunk can be claimed and then filled.
-    // 1 - data from the chunk will be compacted into 1 other chunk; some
-    //     data from the chunk may also be compacted into the chunk itself.
-    // 2 - data from the chunk will be copied to 2 other chunks.
+    // 0 - data from the region will be compacted completely into itself, or the
+    //     region is empty.  The region can be claimed and then filled.
+    // 1 - data from the region will be compacted into 1 other region; some
+    //     data from the region may also be compacted into the region itself.
+    // 2 - data from the region will be copied to 2 other regions.
     //
-    // During compaction as chunks are emptied, the destination_count is
+    // During compaction as regions are emptied, the destination_count is
     // decremented (atomically) and when it reaches 0, it can be claimed and
     // then filled.
     //
-    // A chunk is claimed for processing by atomically changing the
-    // destination_count to the claimed value (dc_claimed).  After a chunk has
+    // A region is claimed for processing by atomically changing the
+    // destination_count to the claimed value (dc_claimed).  After a region has
     // been filled, the destination_count should be set to the completed value
     // (dc_completed).
     inline uint destination_count() const;
     inline uint destination_count_raw() const;
 
-    // The location of the java heap data that corresponds to this chunk.
+    // The location of the java heap data that corresponds to this region.
     inline HeapWord* data_location() const;
 
-    // The highest address referenced by objects in this chunk.
+    // The highest address referenced by objects in this region.
     inline HeapWord* highest_ref() const;
 
-    // Whether this chunk is available to be claimed, has been claimed, or has
+    // Whether this region is available to be claimed, has been claimed, or has
     // been completed.
     //
-    // Minor subtlety:  claimed() returns true if the chunk is marked
-    // completed(), which is desirable since a chunk must be claimed before it
+    // Minor subtlety:  claimed() returns true if the region is marked
+    // completed(), which is desirable since a region must be claimed before it
     // can be completed.
     bool available() const { return _dc_and_los < dc_one; }
     bool claimed() const   { return _dc_and_los >= dc_claimed; }
@@ -164,11 +164,11 @@
 
     // These are not atomic.
     void set_destination(HeapWord* addr)       { _destination = addr; }
-    void set_source_chunk(size_t chunk)        { _source_chunk = chunk; }
+    void set_source_region(size_t region)      { _source_region = region; }
     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }
     void set_partial_obj_size(size_t words)    {
-      _partial_obj_size = (chunk_sz_t) words;
+      _partial_obj_size = (region_sz_t) words;
     }
 
     inline void set_destination_count(uint count);
@@ -184,44 +184,44 @@
     inline bool claim();
 
   private:
-    // The type used to represent object sizes within a chunk.
-    typedef uint chunk_sz_t;
+    // The type used to represent object sizes within a region.
+    typedef uint region_sz_t;
 
     // Constants for manipulating the _dc_and_los field, which holds both the
     // destination count and live obj size.  The live obj size lives at the
     // least significant end so no masking is necessary when adding.
-    static const chunk_sz_t dc_shift;           // Shift amount.
-    static const chunk_sz_t dc_mask;            // Mask for destination count.
-    static const chunk_sz_t dc_one;             // 1, shifted appropriately.
-    static const chunk_sz_t dc_claimed;         // Chunk has been claimed.
-    static const chunk_sz_t dc_completed;       // Chunk has been completed.
-    static const chunk_sz_t los_mask;           // Mask for live obj size.
+    static const region_sz_t dc_shift;           // Shift amount.
+    static const region_sz_t dc_mask;            // Mask for destination count.
+    static const region_sz_t dc_one;             // 1, shifted appropriately.
+    static const region_sz_t dc_claimed;         // Region has been claimed.
+    static const region_sz_t dc_completed;       // Region has been completed.
+    static const region_sz_t los_mask;           // Mask for live obj size.
 
-    HeapWord*           _destination;
-    size_t              _source_chunk;
-    HeapWord*           _partial_obj_addr;
-    chunk_sz_t          _partial_obj_size;
-    chunk_sz_t volatile _dc_and_los;
+    HeapWord*            _destination;
+    size_t               _source_region;
+    HeapWord*            _partial_obj_addr;
+    region_sz_t          _partial_obj_size;
+    region_sz_t volatile _dc_and_los;
 #ifdef ASSERT
     // These enable optimizations that are only partially implemented.  Use
     // debug builds to prevent the code fragments from breaking.
-    HeapWord*           _data_location;
-    HeapWord*           _highest_ref;
+    HeapWord*            _data_location;
+    HeapWord*            _highest_ref;
 #endif  // #ifdef ASSERT
 
 #ifdef ASSERT
    public:
-    uint            _pushed;    // 0 until chunk is pushed onto a worker's stack
+    uint            _pushed;   // 0 until region is pushed onto a worker's stack
    private:
 #endif
   };
 
   // 'Blocks' allow shorter sections of the bitmap to be searched.  Each Block
-  // holds an offset, which is the amount of live data in the Chunk to the left
+  // holds an offset, which is the amount of live data in the Region to the left
   // of the first live object in the Block.  This amount of live data will
   // include any object extending into the block. The first block in
-  // a chunk does not include any partial object extending into the
-  // the chunk.
+  // a region does not include any partial object extending into the
+  // the region.
   //
   // The offset also encodes the
   // 'parity' of the first 1 bit in the Block:  a positive offset means the
@@ -286,27 +286,27 @@
   ParallelCompactData();
   bool initialize(MemRegion covered_region);
 
-  size_t chunk_count() const { return _chunk_count; }
+  size_t region_count() const { return _region_count; }
 
-  // Convert chunk indices to/from ChunkData pointers.
-  inline ChunkData* chunk(size_t chunk_idx) const;
-  inline size_t     chunk(const ChunkData* const chunk_ptr) const;
+  // Convert region indices to/from RegionData pointers.
+  inline RegionData* region(size_t region_idx) const;
+  inline size_t     region(const RegionData* const region_ptr) const;
 
-  // Returns true if the given address is contained within the chunk
-  bool chunk_contains(size_t chunk_index, HeapWord* addr);
+  // Returns true if the given address is contained within the region
+  bool region_contains(size_t region_index, HeapWord* addr);
 
   size_t block_count() const { return _block_count; }
   inline BlockData* block(size_t n) const;
 
-  // Returns true if the given block is in the given chunk.
-  static bool chunk_contains_block(size_t chunk_index, size_t block_index);
+  // Returns true if the given block is in the given region.
+  static bool region_contains_block(size_t region_index, size_t block_index);
 
   void add_obj(HeapWord* addr, size_t len);
   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
 
-  // Fill in the chunks covering [beg, end) so that no data moves; i.e., the
-  // destination of chunk n is simply the start of chunk n.  The argument beg
-  // must be chunk-aligned; end need not be.
+  // Fill in the regions covering [beg, end) so that no data moves; i.e., the
+  // destination of region n is simply the start of region n.  The argument beg
+  // must be region-aligned; end need not be.
   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
 
   bool summarize(HeapWord* target_beg, HeapWord* target_end,
@@ -314,27 +314,27 @@
                  HeapWord** target_next, HeapWord** source_next = 0);
 
   void clear();
-  void clear_range(size_t beg_chunk, size_t end_chunk);
+  void clear_range(size_t beg_region, size_t end_region);
   void clear_range(HeapWord* beg, HeapWord* end) {
-    clear_range(addr_to_chunk_idx(beg), addr_to_chunk_idx(end));
+    clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
   }
 
-  // Return the number of words between addr and the start of the chunk
+  // Return the number of words between addr and the start of the region
   // containing addr.
-  inline size_t     chunk_offset(const HeapWord* addr) const;
+  inline size_t     region_offset(const HeapWord* addr) const;
 
-  // Convert addresses to/from a chunk index or chunk pointer.
-  inline size_t     addr_to_chunk_idx(const HeapWord* addr) const;
-  inline ChunkData* addr_to_chunk_ptr(const HeapWord* addr) const;
-  inline HeapWord*  chunk_to_addr(size_t chunk) const;
-  inline HeapWord*  chunk_to_addr(size_t chunk, size_t offset) const;
-  inline HeapWord*  chunk_to_addr(const ChunkData* chunk) const;
+  // Convert addresses to/from a region index or region pointer.
+  inline size_t     addr_to_region_idx(const HeapWord* addr) const;
+  inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
+  inline HeapWord*  region_to_addr(size_t region) const;
+  inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
+  inline HeapWord*  region_to_addr(const RegionData* region) const;
 
-  inline HeapWord*  chunk_align_down(HeapWord* addr) const;
-  inline HeapWord*  chunk_align_up(HeapWord* addr) const;
-  inline bool       is_chunk_aligned(HeapWord* addr) const;
+  inline HeapWord*  region_align_down(HeapWord* addr) const;
+  inline HeapWord*  region_align_up(HeapWord* addr) const;
+  inline bool       is_region_aligned(HeapWord* addr) const;
 
-  // Analogous to chunk_offset() for blocks.
+  // Analogous to region_offset() for blocks.
   size_t     block_offset(const HeapWord* addr) const;
   size_t     addr_to_block_idx(const HeapWord* addr) const;
   size_t     addr_to_block_idx(const oop obj) const {
@@ -344,7 +344,7 @@
   inline HeapWord*  block_to_addr(size_t block) const;
 
   // Return the address one past the end of the partial object.
-  HeapWord* partial_obj_end(size_t chunk_idx) const;
+  HeapWord* partial_obj_end(size_t region_idx) const;
 
   // Return the new location of the object p after the
   // the compaction.
@@ -353,8 +353,8 @@
   // Same as calc_new_pointer() using blocks.
   HeapWord* block_calc_new_pointer(HeapWord* addr);
 
-  // Same as calc_new_pointer() using chunks.
-  HeapWord* chunk_calc_new_pointer(HeapWord* addr);
+  // Same as calc_new_pointer() using regions.
+  HeapWord* region_calc_new_pointer(HeapWord* addr);
 
   HeapWord* calc_new_pointer(oop p) {
     return calc_new_pointer((HeapWord*) p);
@@ -364,7 +364,7 @@
   klassOop calc_new_klass(klassOop);
 
   // Given a block returns true if the partial object for the
-  // corresponding chunk ends in the block.  Returns false, otherwise
+  // corresponding region ends in the block.  Returns false, otherwise
   // If there is no partial object, returns false.
   bool partial_obj_ends_in_block(size_t block_index);
 
@@ -378,7 +378,7 @@
 
 private:
   bool initialize_block_data(size_t region_size);
-  bool initialize_chunk_data(size_t region_size);
+  bool initialize_region_data(size_t region_size);
   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 
 private:
@@ -387,9 +387,9 @@
   HeapWord*       _region_end;
 #endif  // #ifdef ASSERT
 
-  PSVirtualSpace* _chunk_vspace;
-  ChunkData*      _chunk_data;
-  size_t          _chunk_count;
+  PSVirtualSpace* _region_vspace;
+  RegionData*     _region_data;
+  size_t          _region_count;
 
   PSVirtualSpace* _block_vspace;
   BlockData*      _block_data;
@@ -397,64 +397,64 @@
 };
 
 inline uint
-ParallelCompactData::ChunkData::destination_count_raw() const
+ParallelCompactData::RegionData::destination_count_raw() const
 {
   return _dc_and_los & dc_mask;
 }
 
 inline uint
-ParallelCompactData::ChunkData::destination_count() const
+ParallelCompactData::RegionData::destination_count() const
 {
   return destination_count_raw() >> dc_shift;
 }
 
 inline void
-ParallelCompactData::ChunkData::set_destination_count(uint count)
+ParallelCompactData::RegionData::set_destination_count(uint count)
 {
   assert(count <= (dc_completed >> dc_shift), "count too large");
-  const chunk_sz_t live_sz = (chunk_sz_t) live_obj_size();
+  const region_sz_t live_sz = (region_sz_t) live_obj_size();
   _dc_and_los = (count << dc_shift) | live_sz;
 }
 
-inline void ParallelCompactData::ChunkData::set_live_obj_size(size_t words)
+inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
 {
   assert(words <= los_mask, "would overflow");
-  _dc_and_los = destination_count_raw() | (chunk_sz_t)words;
+  _dc_and_los = destination_count_raw() | (region_sz_t)words;
 }
 
-inline void ParallelCompactData::ChunkData::decrement_destination_count()
+inline void ParallelCompactData::RegionData::decrement_destination_count()
 {
   assert(_dc_and_los < dc_claimed, "already claimed");
   assert(_dc_and_los >= dc_one, "count would go negative");
   Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
 }
 
-inline HeapWord* ParallelCompactData::ChunkData::data_location() const
+inline HeapWord* ParallelCompactData::RegionData::data_location() const
 {
   DEBUG_ONLY(return _data_location;)
   NOT_DEBUG(return NULL;)
 }
 
-inline HeapWord* ParallelCompactData::ChunkData::highest_ref() const
+inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
 {
   DEBUG_ONLY(return _highest_ref;)
   NOT_DEBUG(return NULL;)
 }
 
-inline void ParallelCompactData::ChunkData::set_data_location(HeapWord* addr)
+inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
 {
   DEBUG_ONLY(_data_location = addr;)
 }
 
-inline void ParallelCompactData::ChunkData::set_completed()
+inline void ParallelCompactData::RegionData::set_completed()
 {
   assert(claimed(), "must be claimed first");
-  _dc_and_los = dc_completed | (chunk_sz_t) live_obj_size();
+  _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
 }
 
-// MT-unsafe claiming of a chunk.  Should only be used during single threaded
+// MT-unsafe claiming of a region.  Should only be used during single threaded
 // execution.
-inline bool ParallelCompactData::ChunkData::claim_unsafe()
+inline bool ParallelCompactData::RegionData::claim_unsafe()
 {
   if (available()) {
     _dc_and_los |= dc_claimed;
@@ -463,13 +463,13 @@
   return false;
 }
 
-inline void ParallelCompactData::ChunkData::add_live_obj(size_t words)
+inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
 {
   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
   Atomic::add((int) words, (volatile int*) &_dc_and_los);
 }
 
-inline void ParallelCompactData::ChunkData::set_highest_ref(HeapWord* addr)
+inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
 {
 #ifdef ASSERT
   HeapWord* tmp = _highest_ref;
@@ -479,7 +479,7 @@
 #endif  // #ifdef ASSERT
 }
 
-inline bool ParallelCompactData::ChunkData::claim()
+inline bool ParallelCompactData::RegionData::claim()
 {
   const int los = (int) live_obj_size();
   const int old = Atomic::cmpxchg(dc_claimed | los,
@@ -487,19 +487,19 @@
   return old == los;
 }
 
-inline ParallelCompactData::ChunkData*
-ParallelCompactData::chunk(size_t chunk_idx) const
+inline ParallelCompactData::RegionData*
+ParallelCompactData::region(size_t region_idx) const
 {
-  assert(chunk_idx <= chunk_count(), "bad arg");
-  return _chunk_data + chunk_idx;
+  assert(region_idx <= region_count(), "bad arg");
+  return _region_data + region_idx;
 }
 
 inline size_t
-ParallelCompactData::chunk(const ChunkData* const chunk_ptr) const
+ParallelCompactData::region(const RegionData* const region_ptr) const
 {
-  assert(chunk_ptr >= _chunk_data, "bad arg");
-  assert(chunk_ptr <= _chunk_data + chunk_count(), "bad arg");
-  return pointer_delta(chunk_ptr, _chunk_data, sizeof(ChunkData));
+  assert(region_ptr >= _region_data, "bad arg");
+  assert(region_ptr <= _region_data + region_count(), "bad arg");
+  return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 }
 
 inline ParallelCompactData::BlockData*
@@ -509,68 +509,69 @@
 }
 
 inline size_t
-ParallelCompactData::chunk_offset(const HeapWord* addr) const
+ParallelCompactData::region_offset(const HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
-  return (size_t(addr) & ChunkAddrOffsetMask) >> LogHeapWordSize;
+  return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
 }
 
 inline size_t
-ParallelCompactData::addr_to_chunk_idx(const HeapWord* addr) const
+ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
-  return pointer_delta(addr, _region_start) >> Log2ChunkSize;
+  return pointer_delta(addr, _region_start) >> Log2RegionSize;
 }
 
-inline ParallelCompactData::ChunkData*
-ParallelCompactData::addr_to_chunk_ptr(const HeapWord* addr) const
+inline ParallelCompactData::RegionData*
+ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
 {
-  return chunk(addr_to_chunk_idx(addr));
+  return region(addr_to_region_idx(addr));
 }
 
 inline HeapWord*
-ParallelCompactData::chunk_to_addr(size_t chunk) const
+ParallelCompactData::region_to_addr(size_t region) const
 {
-  assert(chunk <= _chunk_count, "chunk out of range");
-  return _region_start + (chunk << Log2ChunkSize);
+  assert(region <= _region_count, "region out of range");
+  return _region_start + (region << Log2RegionSize);
 }
 
 inline HeapWord*
-ParallelCompactData::chunk_to_addr(const ChunkData* chunk) const
+ParallelCompactData::region_to_addr(const RegionData* region) const
 {
-  return chunk_to_addr(pointer_delta(chunk, _chunk_data, sizeof(ChunkData)));
+  return region_to_addr(pointer_delta(region, _region_data,
+                                      sizeof(RegionData)));
 }
 
 inline HeapWord*
-ParallelCompactData::chunk_to_addr(size_t chunk, size_t offset) const
+ParallelCompactData::region_to_addr(size_t region, size_t offset) const
 {
-  assert(chunk <= _chunk_count, "chunk out of range");
-  assert(offset < ChunkSize, "offset too big");  // This may be too strict.
-  return chunk_to_addr(chunk) + offset;
+  assert(region <= _region_count, "region out of range");
+  assert(offset < RegionSize, "offset too big");  // This may be too strict.
+  return region_to_addr(region) + offset;
 }
 
 inline HeapWord*
-ParallelCompactData::chunk_align_down(HeapWord* addr) const
+ParallelCompactData::region_align_down(HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
-  assert(addr < _region_end + ChunkSize, "bad addr");
-  return (HeapWord*)(size_t(addr) & ChunkAddrMask);
+  assert(addr < _region_end + RegionSize, "bad addr");
+  return (HeapWord*)(size_t(addr) & RegionAddrMask);
 }
 
 inline HeapWord*
-ParallelCompactData::chunk_align_up(HeapWord* addr) const
+ParallelCompactData::region_align_up(HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
-  return chunk_align_down(addr + ChunkSizeOffsetMask);
+  return region_align_down(addr + RegionSizeOffsetMask);
 }
 
 inline bool
-ParallelCompactData::is_chunk_aligned(HeapWord* addr) const
+ParallelCompactData::is_region_aligned(HeapWord* addr) const
 {
-  return chunk_offset(addr) == 0;
+  return region_offset(addr) == 0;
 }
 
 inline size_t
@@ -692,40 +693,39 @@
   // ParallelCompactData::BlockData::blk_ofs_t _live_data_left;
   size_t    _live_data_left;
   size_t    _cur_block;
-  HeapWord* _chunk_start;
-  HeapWord* _chunk_end;
-  size_t    _chunk_index;
+  HeapWord* _region_start;
+  HeapWord* _region_end;
+  size_t    _region_index;
 
  public:
   BitBlockUpdateClosure(ParMarkBitMap* mbm,
                         ParCompactionManager* cm,
-                        size_t chunk_index);
+                        size_t region_index);
 
   size_t cur_block() { return _cur_block; }
-  size_t chunk_index() { return _chunk_index; }
+  size_t region_index() { return _region_index; }
   size_t live_data_left() { return _live_data_left; }
   // Returns true the first bit in the current block (cur_block) is
   // a start bit.
-  // Returns true if the current block is within the chunk for the closure;
-  bool chunk_contains_cur_block();
+  // Returns true if the current block is within the region for the closure;
+  bool region_contains_cur_block();
 
-  // Set the chunk index and related chunk values for
-  // a new chunk.
-  void reset_chunk(size_t chunk_index);
+  // Set the region index and related region values for
+  // a new region.
+  void reset_region(size_t region_index);
 
   virtual IterationStatus do_addr(HeapWord* addr, size_t words);
 };
 
-// The UseParallelOldGC collector is a stop-the-world garbage
-// collector that does parts of the collection using parallel threads.
-// The collection includes the tenured generation and the young
-// generation.  The permanent generation is collected at the same
-// time as the other two generations but the permanent generation
-// is collect by a single GC thread.  The permanent generation is
-// collected serially because of the requirement that during the
-// processing of a klass AAA, any objects reference by AAA must
-// already have been processed.  This requirement is enforced by
-// a left (lower address) to right (higher address) sliding compaction.
+// The UseParallelOldGC collector is a stop-the-world garbage collector that
+// does parts of the collection using parallel threads.  The collection includes
+// the tenured generation and the young generation.  The permanent generation is
+// collected at the same time as the other two generations but the permanent
+// generation is collect by a single GC thread.  The permanent generation is
+// collected serially because of the requirement that during the processing of a
+// klass AAA, any objects reference by AAA must already have been processed.
+// This requirement is enforced by a left (lower address) to right (higher
+// address) sliding compaction.
 //
 // There are four phases of the collection.
 //
@@ -740,80 +740,75 @@
 //      - move the objects to their destination
 //      - update some references and reinitialize some variables
 //
-// These three phases are invoked in PSParallelCompact::invoke_no_policy().
-// The marking phase is implemented in PSParallelCompact::marking_phase()
-// and does a complete marking of the heap.
-// The summary phase is implemented in PSParallelCompact::summary_phase().
-// The move and update phase is implemented in PSParallelCompact::compact().
+// These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
+// marking phase is implemented in PSParallelCompact::marking_phase() and does a
+// complete marking of the heap.  The summary phase is implemented in
+// PSParallelCompact::summary_phase().  The move and update phase is implemented
+// in PSParallelCompact::compact().
 //
-// A space that is being collected is divided into chunks and with
-// each chunk is associated an object of type ParallelCompactData.
-// Each chunk is of a fixed size and typically will contain more than
-// 1 object and may have parts of objects at the front and back of the
-// chunk.
+// A space that is being collected is divided into regions and with each region
+// is associated an object of type ParallelCompactData.  Each region is of a
+// fixed size and typically will contain more than 1 object and may have parts
+// of objects at the front and back of the region.
 //
-// chunk            -----+---------------------+----------
+// region            -----+---------------------+----------
 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 //
-// The marking phase does a complete marking of all live objects in the
-// heap.  The marking also compiles the size of the data for
-// all live objects covered by the chunk.  This size includes the
-// part of any live object spanning onto the chunk (part of AAA
-// if it is live) from the front, all live objects contained in the chunk
-// (BBB and/or CCC if they are live), and the part of any live objects
-// covered by the chunk that extends off the chunk (part of DDD if it is
-// live).  The marking phase uses multiple GC threads and marking is
-// done in a bit array of type ParMarkBitMap.  The marking of the
-// bit map is done atomically as is the accumulation of the size of the
-// live objects covered by a chunk.
+// The marking phase does a complete marking of all live objects in the heap.
+// The marking also compiles the size of the data for all live objects covered
+// by the region.  This size includes the part of any live object spanning onto
+// the region (part of AAA if it is live) from the front, all live objects
+// contained in the region (BBB and/or CCC if they are live), and the part of
+// any live objects covered by the region that extends off the region (part of
+// DDD if it is live).  The marking phase uses multiple GC threads and marking
+// is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
+// done atomically as is the accumulation of the size of the live objects
+// covered by a region.
 //
-// The summary phase calculates the total live data to the left of
-// each chunk XXX.  Based on that total and the bottom of the space,
-// it can calculate the starting location of the live data in XXX.
-// The summary phase calculates for each chunk XXX quantites such as
+// The summary phase calculates the total live data to the left of each region
+// XXX.  Based on that total and the bottom of the space, it can calculate the
+// starting location of the live data in XXX.  The summary phase calculates for
+// each region XXX quantites such as
 //
-//      - the amount of live data at the beginning of a chunk from an object
-//      entering the chunk.
-//      - the location of the first live data on the chunk
-//      - a count of the number of chunks receiving live data from XXX.
+//      - the amount of live data at the beginning of a region from an object
+//        entering the region.
+//      - the location of the first live data on the region
+//      - a count of the number of regions receiving live data from XXX.
 //
 // See ParallelCompactData for precise details.  The summary phase also
-// calculates the dense prefix for the compaction.  The dense prefix
-// is a portion at the beginning of the space that is not moved.  The
-// objects in the dense prefix do need to have their object references
-// updated.  See method summarize_dense_prefix().
+// calculates the dense prefix for the compaction.  The dense prefix is a
+// portion at the beginning of the space that is not moved.  The objects in the
+// dense prefix do need to have their object references updated.  See method
+// summarize_dense_prefix().
 //
 // The summary phase is done using 1 GC thread.
 //
-// The compaction phase moves objects to their new location and updates
-// all references in the object.
+// The compaction phase moves objects to their new location and updates all
+// references in the object.
 //
-// A current exception is that objects that cross a chunk boundary
-// are moved but do not have their references updated.  References are
-// not updated because it cannot easily be determined if the klass
-// pointer KKK for the object AAA has been updated.  KKK likely resides
-// in a chunk to the left of the chunk containing AAA.  These AAA's
-// have there references updated at the end in a clean up phase.
-// See the method PSParallelCompact::update_deferred_objects().  An
-// alternate strategy is being investigated for this deferral of updating.
+// A current exception is that objects that cross a region boundary are moved
+// but do not have their references updated.  References are not updated because
+// it cannot easily be determined if the klass pointer KKK for the object AAA
+// has been updated.  KKK likely resides in a region to the left of the region
+// containing AAA.  These AAA's have there references updated at the end in a
+// clean up phase.  See the method PSParallelCompact::update_deferred_objects().
+// An alternate strategy is being investigated for this deferral of updating.
 //
-// Compaction is done on a chunk basis.  A chunk that is ready to be
-// filled is put on a ready list and GC threads take chunk off the list
-// and fill them.  A chunk is ready to be filled if it
-// empty of live objects.  Such a chunk may have been initially
-// empty (only contained
-// dead objects) or may have had all its live objects copied out already.
-// A chunk that compacts into itself is also ready for filling.  The
-// ready list is initially filled with empty chunks and chunks compacting
-// into themselves.  There is always at least 1 chunk that can be put on
-// the ready list.  The chunks are atomically added and removed from
-// the ready list.
-//
+// Compaction is done on a region basis.  A region that is ready to be filled is
+// put on a ready list and GC threads take region off the list and fill them.  A
+// region is ready to be filled if it empty of live objects.  Such a region may
+// have been initially empty (only contained dead objects) or may have had all
+// its live objects copied out already.  A region that compacts into itself is
+// also ready for filling.  The ready list is initially filled with empty
+// regions and regions compacting into themselves.  There is always at least 1
+// region that can be put on the ready list.  The regions are atomically added
+// and removed from the ready list.
+
 class PSParallelCompact : AllStatic {
  public:
   // Convenient access to type names.
   typedef ParMarkBitMap::idx_t idx_t;
-  typedef ParallelCompactData::ChunkData ChunkData;
+  typedef ParallelCompactData::RegionData RegionData;
   typedef ParallelCompactData::BlockData BlockData;
 
   typedef enum {
@@ -977,26 +972,26 @@
   // not reclaimed).
   static double dead_wood_limiter(double density, size_t min_percent);
 
-  // Find the first (left-most) chunk in the range [beg, end) that has at least
+  // Find the first (left-most) region in the range [beg, end) that has at least
   // dead_words of dead space to the left.  The argument beg must be the first
-  // chunk in the space that is not completely live.
-  static ChunkData* dead_wood_limit_chunk(const ChunkData* beg,
-                                          const ChunkData* end,
-                                          size_t dead_words);
+  // region in the space that is not completely live.
+  static RegionData* dead_wood_limit_region(const RegionData* beg,
+                                            const RegionData* end,
+                                            size_t dead_words);
 
-  // Return a pointer to the first chunk in the range [beg, end) that is not
+  // Return a pointer to the first region in the range [beg, end) that is not
   // completely full.
-  static ChunkData* first_dead_space_chunk(const ChunkData* beg,
-                                           const ChunkData* end);
+  static RegionData* first_dead_space_region(const RegionData* beg,
+                                             const RegionData* end);
 
   // Return a value indicating the benefit or 'yield' if the compacted region
   // were to start (or equivalently if the dense prefix were to end) at the
-  // candidate chunk.  Higher values are better.
+  // candidate region.  Higher values are better.
   //
   // The value is based on the amount of space reclaimed vs. the costs of (a)
   // updating references in the dense prefix plus (b) copying objects and
   // updating references in the compacted region.
-  static inline double reclaimed_ratio(const ChunkData* const candidate,
+  static inline double reclaimed_ratio(const RegionData* const candidate,
                                        HeapWord* const bottom,
                                        HeapWord* const top,
                                        HeapWord* const new_top);
@@ -1005,9 +1000,9 @@
   static HeapWord* compute_dense_prefix(const SpaceId id,
                                         bool maximum_compaction);
 
-  // Return true if dead space crosses onto the specified Chunk; bit must be the
-  // bit index corresponding to the first word of the Chunk.
-  static inline bool dead_space_crosses_boundary(const ChunkData* chunk,
+  // Return true if dead space crosses onto the specified Region; bit must be
+  // the bit index corresponding to the first word of the Region.
+  static inline bool dead_space_crosses_boundary(const RegionData* region,
                                                  idx_t bit);
 
   // Summary phase utility routine to fill dead space (if any) at the dense
@@ -1038,16 +1033,16 @@
   static void compact_perm(ParCompactionManager* cm);
   static void compact();
 
-  // Add available chunks to the stack and draining tasks to the task queue.
-  static void enqueue_chunk_draining_tasks(GCTaskQueue* q,
-                                           uint parallel_gc_threads);
+  // Add available regions to the stack and draining tasks to the task queue.
+  static void enqueue_region_draining_tasks(GCTaskQueue* q,
+                                            uint parallel_gc_threads);
 
   // Add dense prefix update tasks to the task queue.
   static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
                                          uint parallel_gc_threads);
 
-  // Add chunk stealing tasks to the task queue.
-  static void enqueue_chunk_stealing_tasks(
+  // Add region stealing tasks to the task queue.
+  static void enqueue_region_stealing_tasks(
                                        GCTaskQueue* q,
                                        ParallelTaskTerminator* terminator_ptr,
                                        uint parallel_gc_threads);
@@ -1154,56 +1149,56 @@
   // Move and update the live objects in the specified space.
   static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
 
-  // Process the end of the given chunk range in the dense prefix.
+  // Process the end of the given region range in the dense prefix.
   // This includes saving any object not updated.
-  static void dense_prefix_chunks_epilogue(ParCompactionManager* cm,
-                                           size_t chunk_start_index,
-                                           size_t chunk_end_index,
-                                           idx_t exiting_object_offset,
-                                           idx_t chunk_offset_start,
-                                           idx_t chunk_offset_end);
+  static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
+                                            size_t region_start_index,
+                                            size_t region_end_index,
+                                            idx_t exiting_object_offset,
+                                            idx_t region_offset_start,
+                                            idx_t region_offset_end);
 
-  // Update a chunk in the dense prefix.  For each live object
-  // in the chunk, update it's interior references.  For each
+  // Update a region in the dense prefix.  For each live object
+  // in the region, update it's interior references.  For each
   // dead object, fill it with deadwood. Dead space at the end
-  // of a chunk range will be filled to the start of the next
-  // live object regardless of the chunk_index_end.  None of the
+  // of a region range will be filled to the start of the next
+  // live object regardless of the region_index_end.  None of the
   // objects in the dense prefix move and dead space is dead
   // (holds only dead objects that don't need any processing), so
   // dead space can be filled in any order.
   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
                                                   SpaceId space_id,
-                                                  size_t chunk_index_start,
-                                                  size_t chunk_index_end);
+                                                  size_t region_index_start,
+                                                  size_t region_index_end);
 
   // Return the address of the count + 1st live word in the range [beg, end).
   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
 
   // Return the address of the word to be copied to dest_addr, which must be
-  // aligned to a chunk boundary.
+  // aligned to a region boundary.
   static HeapWord* first_src_addr(HeapWord* const dest_addr,
-                                  size_t src_chunk_idx);
+                                  size_t src_region_idx);
 
-  // Determine the next source chunk, set closure.source() to the start of the
-  // new chunk return the chunk index.  Parameter end_addr is the address one
+  // Determine the next source region, set closure.source() to the start of the
+  // new region return the region index.  Parameter end_addr is the address one
   // beyond the end of source range just processed.  If necessary, switch to a
   // new source space and set src_space_id (in-out parameter) and src_space_top
   // (out parameter) accordingly.
-  static size_t next_src_chunk(MoveAndUpdateClosure& closure,
-                               SpaceId& src_space_id,
-                               HeapWord*& src_space_top,
-                               HeapWord* end_addr);
+  static size_t next_src_region(MoveAndUpdateClosure& closure,
+                                SpaceId& src_space_id,
+                                HeapWord*& src_space_top,
+                                HeapWord* end_addr);
 
-  // Decrement the destination count for each non-empty source chunk in the
-  // range [beg_chunk, chunk(chunk_align_up(end_addr))).
+  // Decrement the destination count for each non-empty source region in the
+  // range [beg_region, region(region_align_up(end_addr))).
   static void decrement_destination_counts(ParCompactionManager* cm,
-                                           size_t beg_chunk,
+                                           size_t beg_region,
                                            HeapWord* end_addr);
 
-  // Fill a chunk, copying objects from one or more source chunks.
-  static void fill_chunk(ParCompactionManager* cm, size_t chunk_idx);
-  static void fill_and_update_chunk(ParCompactionManager* cm, size_t chunk) {
-    fill_chunk(cm, chunk);
+  // Fill a region, copying objects from one or more source regions.
+  static void fill_region(ParCompactionManager* cm, size_t region_idx);
+  static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
+    fill_region(cm, region);
   }
 
   // Update the deferred objects in the space.
@@ -1259,7 +1254,7 @@
 #ifndef PRODUCT
   // Debugging support.
   static const char* space_names[last_space_id];
-  static void print_chunk_ranges();
+  static void print_region_ranges();
   static void print_dense_prefix_stats(const char* const algorithm,
                                        const SpaceId id,
                                        const bool maximum_compaction,
@@ -1267,7 +1262,7 @@
 #endif  // #ifndef PRODUCT
 
 #ifdef  ASSERT
-  // Verify that all the chunks have been emptied.
+  // Verify that all the regions have been emptied.
   static void verify_complete(SpaceId space_id);
 #endif  // #ifdef ASSERT
 };
@@ -1376,17 +1371,17 @@
 }
 
 inline bool
-PSParallelCompact::dead_space_crosses_boundary(const ChunkData* chunk,
+PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
                                                idx_t bit)
 {
-  assert(bit > 0, "cannot call this for the first bit/chunk");
-  assert(_summary_data.chunk_to_addr(chunk) == _mark_bitmap.bit_to_addr(bit),
+  assert(bit > 0, "cannot call this for the first bit/region");
+  assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
          "sanity check");
 
   // Dead space crosses the boundary if (1) a partial object does not extend
-  // onto the chunk, (2) an object does not start at the beginning of the chunk,
-  // and (3) an object does not end at the end of the prior chunk.
-  return chunk->partial_obj_size() == 0 &&
+  // onto the region, (2) an object does not start at the beginning of the
+  // region, and (3) an object does not end at the end of the prior region.
+  return region->partial_obj_size() == 0 &&
     !_mark_bitmap.is_obj_beg(bit) &&
     !_mark_bitmap.is_obj_end(bit - 1);
 }
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/runtime/globals.hpp
--- a/hotspot/src/share/vm/runtime/globals.hpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/runtime/globals.hpp	Tue Sep 30 12:20:22 2008 -0700
@@ -1157,9 +1157,9 @@
           "In the Parallel Old garbage collector use parallel dense"        \
           " prefix update")                                                 \
                                                                             \
-  develop(bool, UseParallelOldGCChunkPointerCalc, true,                     \
-          "In the Parallel Old garbage collector use chucks to calculate"   \
-          " new object locations")                                          \
+  develop(bool, UseParallelOldGCRegionPointerCalc, true,                    \
+          "In the Parallel Old garbage collector use regions to calculate"  \
+          "new object locations")                                           \
                                                                             \
   product(uintx, HeapMaximumCompactionInterval, 20,                         \
           "How often should we maximally compact the heap (not allowing "   \
@@ -1195,8 +1195,8 @@
   develop(bool, ParallelOldMTUnsafeUpdateLiveData, false,                   \
           "Use the Parallel Old MT unsafe in update of live size")          \
                                                                             \
-  develop(bool, TraceChunkTasksQueuing, false,                              \
-          "Trace the queuing of the chunk tasks")                           \
+  develop(bool, TraceRegionTasksQueuing, false,                             \
+          "Trace the queuing of the region tasks")                          \
                                                                             \
   product(uintx, ParallelMarkingThreads, 0,                                 \
           "Number of marking threads concurrent gc will use")               \
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/utilities/taskqueue.cpp
--- a/hotspot/src/share/vm/utilities/taskqueue.cpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/utilities/taskqueue.cpp	Tue Sep 30 12:20:22 2008 -0700
@@ -109,72 +109,72 @@
   }
 }
 
-bool ChunkTaskQueueWithOverflow::is_empty() {
-  return (_chunk_queue.size() == 0) &&
+bool RegionTaskQueueWithOverflow::is_empty() {
+  return (_region_queue.size() == 0) &&
          (_overflow_stack->length() == 0);
 }
 
-bool ChunkTaskQueueWithOverflow::stealable_is_empty() {
-  return _chunk_queue.size() == 0;
+bool RegionTaskQueueWithOverflow::stealable_is_empty() {
+  return _region_queue.size() == 0;
 }
 
-bool ChunkTaskQueueWithOverflow::overflow_is_empty() {
+bool RegionTaskQueueWithOverflow::overflow_is_empty() {
   return _overflow_stack->length() == 0;
 }
 
-void ChunkTaskQueueWithOverflow::initialize() {
-  _chunk_queue.initialize();
+void RegionTaskQueueWithOverflow::initialize() {
+  _region_queue.initialize();
   assert(_overflow_stack == 0, "Creating memory leak");
   _overflow_stack =
-    new (ResourceObj::C_HEAP) GrowableArray<ChunkTask>(10, true);
+    new (ResourceObj::C_HEAP) GrowableArray<RegionTask>(10, true);
 }
 
-void ChunkTaskQueueWithOverflow::save(ChunkTask t) {
-  if (TraceChunkTasksQueuing && Verbose) {
+void RegionTaskQueueWithOverflow::save(RegionTask t) {
+  if (TraceRegionTasksQueuing && Verbose) {
     gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
   }
-  if(!_chunk_queue.push(t)) {
+  if(!_region_queue.push(t)) {
     _overflow_stack->push(t);
   }
 }
 
-// Note that using this method will retrieve all chunks
+// Note that using this method will retrieve all regions
 // that have been saved but that it will always check
 // the overflow stack.  It may be more efficient to
 // check the stealable queue and the overflow stack
 // separately.
-bool ChunkTaskQueueWithOverflow::retrieve(ChunkTask& chunk_task) {
-  bool result = retrieve_from_overflow(chunk_task);
+bool RegionTaskQueueWithOverflow::retrieve(RegionTask& region_task) {
+  bool result = retrieve_from_overflow(region_task);
   if (!result) {
-    result = retrieve_from_stealable_queue(chunk_task);
+    result = retrieve_from_stealable_queue(region_task);
   }
-  if (TraceChunkTasksQueuing && Verbose && result) {
+  if (TraceRegionTasksQueuing && Verbose && result) {
     gclog_or_tty->print_cr("  CTQ: retrieve " PTR_FORMAT, result);
   }
   return result;
 }
 
-bool ChunkTaskQueueWithOverflow::retrieve_from_stealable_queue(
-                                   ChunkTask& chunk_task) {
-  bool result = _chunk_queue.pop_local(chunk_task);
-  if (TraceChunkTasksQueuing && Verbose) {
-    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+bool RegionTaskQueueWithOverflow::retrieve_from_stealable_queue(
+                                   RegionTask& region_task) {
+  bool result = _region_queue.pop_local(region_task);
+  if (TraceRegionTasksQueuing && Verbose) {
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
   }
   return result;
 }
 
-bool ChunkTaskQueueWithOverflow::retrieve_from_overflow(
-                                        ChunkTask& chunk_task) {
+bool
+RegionTaskQueueWithOverflow::retrieve_from_overflow(RegionTask& region_task) {
   bool result;
   if (!_overflow_stack->is_empty()) {
-    chunk_task = _overflow_stack->pop();
+    region_task = _overflow_stack->pop();
     result = true;
   } else {
-    chunk_task = (ChunkTask) NULL;
+    region_task = (RegionTask) NULL;
     result = false;
   }
-  if (TraceChunkTasksQueuing && Verbose) {
-    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+  if (TraceRegionTasksQueuing && Verbose) {
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
   }
   return result;
 }
diff -r e5e2b519fc11 -r 9006b01ba3fd hotspot/src/share/vm/utilities/taskqueue.hpp
--- a/hotspot/src/share/vm/utilities/taskqueue.hpp	Tue Sep 30 11:49:31 2008 -0700
+++ b/hotspot/src/share/vm/utilities/taskqueue.hpp	Tue Sep 30 12:20:22 2008 -0700
@@ -557,32 +557,32 @@
 typedef GenericTaskQueue<StarTask>     OopStarTaskQueue;
 typedef GenericTaskQueueSet<StarTask>  OopStarTaskQueueSet;
 
-typedef size_t ChunkTask;  // index for chunk
-typedef GenericTaskQueue<ChunkTask>    ChunkTaskQueue;
-typedef GenericTaskQueueSet<ChunkTask> ChunkTaskQueueSet;
+typedef size_t RegionTask;  // index for region
+typedef GenericTaskQueue<RegionTask>    RegionTaskQueue;
+typedef GenericTaskQueueSet<RegionTask> RegionTaskQueueSet;
 
-class ChunkTaskQueueWithOverflow: public CHeapObj {
+class RegionTaskQueueWithOverflow: public CHeapObj {
  protected:
-  ChunkTaskQueue              _chunk_queue;
-  GrowableArray<ChunkTask>*   _overflow_stack;
+  RegionTaskQueue              _region_queue;
+  GrowableArray<RegionTask>*   _overflow_stack;
 
  public:
-  ChunkTaskQueueWithOverflow() : _overflow_stack(NULL) {}
+  RegionTaskQueueWithOverflow() : _overflow_stack(NULL) {}
   // Initialize both stealable queue and overflow
   void initialize();
   // Save first to stealable queue and then to overflow
-  void save(ChunkTask t);
+  void save(RegionTask t);
   // Retrieve first from overflow and then from stealable queue
-  bool retrieve(ChunkTask& chunk_index);
+  bool retrieve(RegionTask& region_index);
   // Retrieve from stealable queue
-  bool retrieve_from_stealable_queue(ChunkTask& chunk_index);
+  bool retrieve_from_stealable_queue(RegionTask& region_index);
   // Retrieve from overflow
-  bool retrieve_from_overflow(ChunkTask& chunk_index);
+  bool retrieve_from_overflow(RegionTask& region_index);
   bool is_empty();
   bool stealable_is_empty();
   bool overflow_is_empty();
-  juint stealable_size() { return _chunk_queue.size(); }
-  ChunkTaskQueue* task_queue() { return &_chunk_queue; }
+  juint stealable_size() { return _region_queue.size(); }
+  RegionTaskQueue* task_queue() { return &_region_queue; }
 };
 
-#define USE_ChunkTaskQueueWithOverflow
+#define USE_RegionTaskQueueWithOverflow