6725697: par compact - rename class ChunkData to RegionData

Reviewed-by: iveresov, tonyp

hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.cpp

@@ -146,7 +146,7 @@ void RefProcTaskExecutor::execute(ProcessTask& task)
 {
   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 @@ void StealMarkingTask::do_it(GCTaskManager* manager, uint which) {
 }
 
 //
-// StealChunkCompactionTask
+// StealRegionCompactionTask
 //
 
 
-StealChunkCompactionTask::StealChunkCompactionTask(ParallelTaskTerminator* t) :
+StealRegionCompactionTask::StealRegionCompactionTask(ParallelTaskTerminator* t):
-  _terminator(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)) {
+    if (ParCompactionManager::steal(which, &random_seed, region_index)) {
-      PSParallelCompact::fill_and_update_chunk(cm, chunk_index);
+      PSParallelCompact::fill_and_update_region(cm, region_index);
-      cm->drain_chunk_stacks();
+      cm->drain_region_stacks();
     } else {
       if (terminator()->offer_termination()) {
         break;
@@ -249,11 +249,10 @@ void StealChunkCompactionTask::do_it(GCTaskManager* manager, uint which) {
 
 UpdateDensePrefixTask::UpdateDensePrefixTask(
                                    PSParallelCompact::SpaceId space_id,
-                                   size_t chunk_index_start,
+                                   size_t region_index_start,
-                                   size_t chunk_index_end) :
+                                   size_t region_index_end) :
-  _space_id(space_id), _chunk_index_start(chunk_index_start),
+  _space_id(space_id), _region_index_start(region_index_start),
-  _chunk_index_end(chunk_index_end)
+  _region_index_end(region_index_end) {}
-{}
 
 void UpdateDensePrefixTask::do_it(GCTaskManager* manager, uint which) {
 
@@ -265,8 +264,8 @@ void UpdateDensePrefixTask::do_it(GCTaskManager* manager, uint which) {
 
   PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
                                                          _space_id,
-                                                         _chunk_index_start,
+                                                         _region_index_start,
-                                                         _chunk_index_end);
+                                                         _region_index_end);
 }
 
 void DrainStacksCompactionTask::do_it(GCTaskManager* manager, uint which) {
@@ -278,6 +277,6 @@ void DrainStacksCompactionTask::do_it(GCTaskManager* manager, uint which) {
   ParCompactionManager* cm =
     ParCompactionManager::gc_thread_compaction_manager(which);
 
-  // Process any chunks already in the compaction managers stacks.
+  // Process any regions already in the compaction managers stacks.
-  cm->drain_chunk_stacks();
+  cm->drain_region_stacks();
 }

hotspot/src/share/vm/gc_implementation/parallelScavenge/pcTasks.hpp

@@ -188,18 +188,18 @@ class StealMarkingTask : public GCTask {
 };
 
 //
-// 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 StealChunkCompactionTask : public GCTask {
 class UpdateDensePrefixTask : public GCTask {
  private:
   PSParallelCompact::SpaceId _space_id;
-  size_t _chunk_index_start;
+  size_t _region_index_start;
-  size_t _chunk_index_end;
+  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 region_index_start,
-                        size_t chunk_index_end);
+                        size_t region_index_end);
 
   virtual void do_it(GCTaskManager* manager, uint which);
 };
@@ -231,17 +231,17 @@ class UpdateDensePrefixTask : public GCTask {
 //
 // 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);
 };

hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.cpp

@@ -30,7 +30,7 @@ ParCompactionManager**  ParCompactionManager::_manager_array = NULL;
 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 @@ ParCompactionManager::ParCompactionManager() :
 
   // We want the overflow stack to be permanent
   _overflow_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(10, true);
-#ifdef USE_ChunkTaskQueueWithOverflow
+#ifdef USE_RegionTaskQueueWithOverflow
-  chunk_stack()->initialize();
+  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 @@ void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
 
   _stack_array = new OopTaskQueueSet(parallel_gc_threads);
   guarantee(_stack_array != NULL, "Count not initialize promotion manager");
-  _chunk_array = new ChunkTaskQueueSet(parallel_gc_threads);
+  _region_array = new RegionTaskQueueSet(parallel_gc_threads);
-  guarantee(_chunk_array != NULL, "Count not initialize promotion manager");
+  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
+#ifdef USE_RegionTaskQueueWithOverflow
-    chunk_array()->register_queue(i, _manager_array[i]->chunk_stack()->task_queue());
+    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 @@ oop ParCompactionManager::retrieve_for_scanning() {
   return NULL;
 }
 
-// Save chunk on a stack
+// Save region on a stack
-void ParCompactionManager::save_for_processing(size_t chunk_index) {
+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);
+  ParallelCompactData::RegionData* const region_ptr = sd.region(region_index);
-  assert(chunk_ptr->claimed(), "must be claimed");
+  assert(region_ptr->claimed(), "must be claimed");
-  assert(chunk_ptr->_pushed++ == 0, "should only be pushed once");
+  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
+#ifdef USE_RegionTaskQueueWithOverflow
-  chunk_stack()->save(chunk_index);
+  region_stack()->save(region_index);
 #else
-  if(!chunk_stack()->push(chunk_index)) {
+  if(!region_stack()->push(region_index)) {
-    chunk_overflow_stack()->push(chunk_index);
+    region_overflow_stack()->push(region_index);
   }
 #endif
 }
 
-bool ParCompactionManager::retrieve_for_processing(size_t& chunk_index) {
+bool ParCompactionManager::retrieve_for_processing(size_t& region_index) {
-#ifdef USE_ChunkTaskQueueWithOverflow
+#ifdef USE_RegionTaskQueueWithOverflow
-  return chunk_stack()->retrieve(chunk_index);
+  return region_stack()->retrieve(region_index);
 #else
   // Should not be used in the parallel case
   ShouldNotReachHere();
@@ -230,14 +230,14 @@ void ParCompactionManager::drain_marking_stacks(OopClosure* blk) {
   assert(overflow_stack()->length() == 0, "Sanity");
 }
 
-void ParCompactionManager::drain_chunk_overflow_stack() {
+void ParCompactionManager::drain_region_overflow_stack() {
-  size_t chunk_index = (size_t) -1;
+  size_t region_index = (size_t) -1;
-  while(chunk_stack()->retrieve_from_overflow(chunk_index)) {
+  while(region_stack()->retrieve_from_overflow(region_index)) {
-    PSParallelCompact::fill_and_update_chunk(this, chunk_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 @@ void ParCompactionManager::drain_chunk_stacks() {
 #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;
+    size_t region_index = (size_t) -1;
-    while(chunk_stack()->retrieve_from_overflow(chunk_index)) {
+    while(region_stack()->retrieve_from_overflow(region_index)) {
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+      PSParallelCompact::fill_and_update_region(this, region_index);
     }
 
-    while (chunk_stack()->retrieve_from_stealable_queue(chunk_index)) {
+    while (region_stack()->retrieve_from_stealable_queue(region_index)) {
-      PSParallelCompact::fill_and_update_chunk(this, chunk_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()) {
+    while(!region_overflow_stack()->is_empty()) {
-      size_t chunk_index = chunk_overflow_stack()->pop();
+      size_t region_index = region_overflow_stack()->pop();
-      PSParallelCompact::fill_and_update_chunk(this, chunk_index);
+      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) ||
+  } while((region_stack()->size() != 0) ||
-          (chunk_overflow_stack()->length() != 0));
+          (region_overflow_stack()->length() != 0));
 #endif
 
-#ifdef USE_ChunkTaskQueueWithOverflow
+#ifdef USE_RegionTaskQueueWithOverflow
-  assert(chunk_stack()->is_empty(), "Sanity");
+  assert(region_stack()->is_empty(), "Sanity");
 #else
-  assert(chunk_stack()->size() == 0, "Sanity");
+  assert(region_stack()->size() == 0, "Sanity");
-  assert(chunk_overflow_stack()->length() == 0, "Sanity");
+  assert(region_overflow_stack()->length() == 0, "Sanity");
 #endif
 #else
   oop obj;

hotspot/src/share/vm/gc_implementation/parallelScavenge/psCompactionManager.hpp

@@ -52,7 +52,7 @@ class ParCompactionManager : public CHeapObj {
   friend class ParallelTaskTerminator;
   friend class ParMarkBitMap;
   friend class PSParallelCompact;
-  friend class StealChunkCompactionTask;
+  friend class StealRegionCompactionTask;
   friend class UpdateAndFillClosure;
   friend class RefProcTaskExecutor;
 
@@ -75,20 +75,20 @@ class ParCompactionManager : public CHeapObj {
   static ParCompactionManager** _manager_array;
   static OopTaskQueueSet*       _stack_array;
   static ObjectStartArray*      _start_array;
-  static ChunkTaskQueueSet*    _chunk_array;
+  static RegionTaskQueueSet*    _region_array;
   static PSOldGen*              _old_gen;
 
   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
+#ifdef USE_RegionTaskQueueWithOverflow
-  ChunkTaskQueueWithOverflow   _chunk_stack;
+  RegionTaskQueueWithOverflow   _region_stack;
 #else
-  ChunkTaskQueue               _chunk_stack;
+  RegionTaskQueue               _region_stack;
-  GrowableArray<size_t>*       _chunk_overflow_stack;
+  GrowableArray<size_t>*        _region_overflow_stack;
 #endif
 
 #if 1  // does this happen enough to need a per thread stack?
@@ -106,15 +106,16 @@ class ParCompactionManager : public CHeapObj {
 
  protected:
   // Array of tasks.  Needed by the ParallelTaskTerminator.
-  static ChunkTaskQueueSet* chunk_array()   { return _chunk_array; }
+  static RegionTaskQueueSet* region_array()      { return _region_array; }
-
   OopTaskQueue*  marking_stack()                 { return &_marking_stack; }
   GrowableArray<oop>* overflow_stack()           { return _overflow_stack; }
-#ifdef USE_ChunkTaskQueueWithOverflow
+#ifdef USE_RegionTaskQueueWithOverflow
-  ChunkTaskQueueWithOverflow* chunk_stack() { return &_chunk_stack; }
+  RegionTaskQueueWithOverflow* region_stack()    { return &_region_stack; }
 #else
-  ChunkTaskQueue*  chunk_stack()          { return &_chunk_stack; }
+  RegionTaskQueue*  region_stack()               { return &_region_stack; }
-  GrowableArray<size_t>* chunk_overflow_stack() { return _chunk_overflow_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 @@ class ParCompactionManager : public CHeapObj {
   // 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 region stack.  If the region stack is full,
-  // pushes onto the chunk overflow stack.
+  // pushes onto the region overflow stack.
-  void chunk_stack_push(size_t chunk_index);
+  void region_stack_push(size_t region_index);
  public:
 
   Action action() { return _action; }
@@ -160,10 +161,10 @@ class ParCompactionManager : public CHeapObj {
   // Get a oop for scanning.  If returns null, no oop were found.
   oop retrieve_for_scanning();
 
-  // Save chunk for later processing.  Must not fail.
+  // Save region for later processing.  Must not fail.
-  void save_for_processing(size_t chunk_index);
+  void save_for_processing(size_t region_index);
-  // Get a chunk for processing.  If returns null, no chunk were found.
+  // Get a region for processing.  If returns null, no region were found.
-  bool retrieve_for_processing(size_t& chunk_index);
+  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 @@ class ParCompactionManager : public CHeapObj {
     return stack_array()->steal(queue_num, seed, t);
   }
 
-  static bool steal(int queue_num, int* seed, ChunkTask& t) {
+  static bool steal(int queue_num, int* seed, RegionTask& t) {
-    return chunk_array()->steal(queue_num, seed, 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

hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp

@@ -76,87 +76,87 @@ class ParallelCompactData
 {
 public:
   // Sizes are in HeapWords, unless indicated otherwise.
-  static const size_t Log2ChunkSize;
+  static const size_t Log2RegionSize;
-  static const size_t ChunkSize;
+  static const size_t RegionSize;
-  static const size_t ChunkSizeBytes;
+  static const size_t RegionSizeBytes;
 
-  // Mask for the bits in a size_t to get an offset within a chunk.
+  // Mask for the bits in a size_t to get an offset within a region.
-  static const size_t ChunkSizeOffsetMask;
+  static const size_t RegionSizeOffsetMask;
-  // Mask for the bits in a pointer to get an offset within a chunk.
+  // Mask for the bits in a pointer to get an offset within a region.
-  static const size_t ChunkAddrOffsetMask;
+  static const size_t RegionAddrOffsetMask;
-  // Mask for the bits in a pointer to get the address of the start of a chunk.
+  // Mask for the bits in a pointer to get the address of the start of a region.
-  static const size_t ChunkAddrMask;
+  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.
+    // The first region containing data destined for this region.
-    size_t source_chunk() const { return _source_chunk; }
+    size_t source_region() const { return _source_region; }
 
-    // The object (if any) starting in this chunk and ending in a different
+    // The object (if any) starting in this region and ending in a different
-    // chunk that could not be updated during the main (parallel) compaction
+    // 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
+    // Size of live data that lies within this region due to objects that start
-    // in this chunk (words).  This does not include the partial object
+    // in this region (words).  This does not include the partial object
-    // extending onto the chunk (if any), or the part of an object that extends
+    // extending onto the region (if any), or the part of an object that extends
-    // onto the next chunk (if any).
+    // 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
+    // The destination_count is the number of other regions to which data from
-    // this chunk will be copied.  At the end of the summary phase, the valid
+    // 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
+    // 0 - data from the region will be compacted completely into itself, or the
-    //     chunk is empty.  The chunk can be claimed and then filled.
+    //     region is empty.  The region can be claimed and then filled.
-    // 1 - data from the chunk will be compacted into 1 other chunk; some
+    // 1 - data from the region will be compacted into 1 other region; some
-    //     data from the chunk may also be compacted into the chunk itself.
+    //     data from the region may also be compacted into the region itself.
-    // 2 - data from the chunk will be copied to 2 other chunks.
+    // 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
+    // A region is claimed for processing by atomically changing the
-    // destination_count to the claimed value (dc_claimed).  After a chunk has
+    // 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
+    // Minor subtlety:  claimed() returns true if the region is marked
-    // completed(), which is desirable since a chunk must be claimed before it
+    // 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 @@ public:
 
     // 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);
@@ -184,24 +184,24 @@ public:
     inline bool claim();
 
   private:
-    // The type used to represent object sizes within a chunk.
+    // The type used to represent object sizes within a region.
-    typedef uint chunk_sz_t;
+    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 region_sz_t dc_shift;           // Shift amount.
-    static const chunk_sz_t dc_mask;            // Mask for destination count.
+    static const region_sz_t dc_mask;            // Mask for destination count.
-    static const chunk_sz_t dc_one;             // 1, shifted appropriately.
+    static const region_sz_t dc_one;             // 1, shifted appropriately.
-    static const chunk_sz_t dc_claimed;         // Chunk has been claimed.
+    static const region_sz_t dc_claimed;         // Region has been claimed.
-    static const chunk_sz_t dc_completed;       // Chunk has been completed.
+    static const region_sz_t dc_completed;       // Region has been completed.
-    static const chunk_sz_t los_mask;           // Mask for live obj size.
+    static const region_sz_t los_mask;           // Mask for live obj size.
 
     HeapWord*            _destination;
-    size_t              _source_chunk;
+    size_t               _source_region;
     HeapWord*            _partial_obj_addr;
-    chunk_sz_t          _partial_obj_size;
+    region_sz_t          _partial_obj_size;
-    chunk_sz_t volatile _dc_and_los;
+    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.
@@ -211,17 +211,17 @@ public:
 
 #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
+  // a region does not include any partial object extending into the
-  // the chunk.
+  // 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 @@ public:
   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.
+  // Convert region indices to/from RegionData pointers.
-  inline ChunkData* chunk(size_t chunk_idx) const;
+  inline RegionData* region(size_t region_idx) const;
-  inline size_t     chunk(const ChunkData* const chunk_ptr) const;
+  inline size_t     region(const RegionData* const region_ptr) const;
 
-  // Returns true if the given address is contained within the chunk
+  // Returns true if the given address is contained within the region
-  bool chunk_contains(size_t chunk_index, HeapWord* addr);
+  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.
+  // Returns true if the given block is in the given region.
-  static bool chunk_contains_block(size_t chunk_index, size_t block_index);
+  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
+  // Fill in the regions 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
+  // destination of region n is simply the start of region n.  The argument beg
-  // must be chunk-aligned; end need not be.
+  // 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 @@ public:
                  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.
+  // Convert addresses to/from a region index or region pointer.
-  inline size_t     addr_to_chunk_idx(const HeapWord* addr) const;
+  inline size_t     addr_to_region_idx(const HeapWord* addr) const;
-  inline ChunkData* addr_to_chunk_ptr(const HeapWord* addr) const;
+  inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
-  inline HeapWord*  chunk_to_addr(size_t chunk) const;
+  inline HeapWord*  region_to_addr(size_t region) const;
-  inline HeapWord*  chunk_to_addr(size_t chunk, size_t offset) const;
+  inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
-  inline HeapWord*  chunk_to_addr(const ChunkData* chunk) const;
+  inline HeapWord*  region_to_addr(const RegionData* region) const;
 
-  inline HeapWord*  chunk_align_down(HeapWord* addr) const;
+  inline HeapWord*  region_align_down(HeapWord* addr) const;
-  inline HeapWord*  chunk_align_up(HeapWord* addr) const;
+  inline HeapWord*  region_align_up(HeapWord* addr) const;
-  inline bool       is_chunk_aligned(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 @@ public:
   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 @@ public:
   // Same as calc_new_pointer() using blocks.
   HeapWord* block_calc_new_pointer(HeapWord* addr);
 
-  // Same as calc_new_pointer() using chunks.
+  // Same as calc_new_pointer() using regions.
-  HeapWord* chunk_calc_new_pointer(HeapWord* addr);
+  HeapWord* region_calc_new_pointer(HeapWord* addr);
 
   HeapWord* calc_new_pointer(oop p) {
     return calc_new_pointer((HeapWord*) p);
@@ -364,7 +364,7 @@ public:
   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 @@ public:
 
 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 @@ private:
   HeapWord*       _region_end;
 #endif  // #ifdef ASSERT
 
-  PSVirtualSpace* _chunk_vspace;
+  PSVirtualSpace* _region_vspace;
-  ChunkData*      _chunk_data;
+  RegionData*     _region_data;
-  size_t          _chunk_count;
+  size_t          _region_count;
 
   PSVirtualSpace* _block_vspace;
   BlockData*      _block_data;
@@ -397,64 +397,64 @@ private:
 };
 
 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 @@ inline bool ParallelCompactData::ChunkData::claim_unsafe()
   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 @@ inline void ParallelCompactData::ChunkData::set_highest_ref(HeapWord* addr)
 #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 @@ inline bool ParallelCompactData::ChunkData::claim()
   return old == los;
 }
 
-inline ParallelCompactData::ChunkData*
+inline ParallelCompactData::RegionData*
-ParallelCompactData::chunk(size_t chunk_idx) const
+ParallelCompactData::region(size_t region_idx) const
 {
-  assert(chunk_idx <= chunk_count(), "bad arg");
+  assert(region_idx <= region_count(), "bad arg");
-  return _chunk_data + chunk_idx;
+  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(region_ptr >= _region_data, "bad arg");
-  assert(chunk_ptr <= _chunk_data + chunk_count(), "bad arg");
+  assert(region_ptr <= _region_data + region_count(), "bad arg");
-  return pointer_delta(chunk_ptr, _chunk_data, sizeof(ChunkData));
+  return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 }
 
 inline ParallelCompactData::BlockData*
@@ -509,68 +509,69 @@ ParallelCompactData::block(size_t n) const {
 }
 
 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*
+inline ParallelCompactData::RegionData*
-ParallelCompactData::addr_to_chunk_ptr(const HeapWord* addr) const
+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");
+  assert(region <= _region_count, "region out of range");
-  return _region_start + (chunk << Log2ChunkSize);
+  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(region <= _region_count, "region out of range");
-  assert(offset < ChunkSize, "offset too big");  // This may be too strict.
+  assert(offset < RegionSize, "offset too big");  // This may be too strict.
-  return chunk_to_addr(chunk) + offset;
+  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");
+  assert(addr < _region_end + RegionSize, "bad addr");
-  return (HeapWord*)(size_t(addr) & ChunkAddrMask);
+  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 @@ class BitBlockUpdateClosure: public ParMarkBitMapClosure {
   // ParallelCompactData::BlockData::blk_ofs_t _live_data_left;
   size_t    _live_data_left;
   size_t    _cur_block;
-  HeapWord* _chunk_start;
+  HeapWord* _region_start;
-  HeapWord* _chunk_end;
+  HeapWord* _region_end;
-  size_t    _chunk_index;
+  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;
+  // Returns true if the current block is within the region for the closure;
-  bool chunk_contains_cur_block();
+  bool region_contains_cur_block();
 
-  // Set the chunk index and related chunk values for
+  // Set the region index and related region values for
-  // a new chunk.
+  // a new region.
-  void reset_chunk(size_t chunk_index);
+  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
+// The UseParallelOldGC collector is a stop-the-world garbage collector that
-// collector that does parts of the collection using parallel threads.
+// does parts of the collection using parallel threads.  The collection includes
-// The collection includes the tenured generation and the young
+// the tenured generation and the young generation.  The permanent generation is
-// generation.  The permanent generation is collected at the same
+// collected at the same time as the other two generations but the permanent
-// time as the other two generations but the permanent generation
+// generation is collect by a single GC thread.  The permanent generation is
-// is collect by a single GC thread.  The permanent generation is
+// collected serially because of the requirement that during the processing of a
-// collected serially because of the requirement that during the
+// klass AAA, any objects reference by AAA must already have been processed.
-// processing of a klass AAA, any objects reference by AAA must
+// This requirement is enforced by a left (lower address) to right (higher
-// already have been processed.  This requirement is enforced by
+// address) sliding compaction.
-// a left (lower address) to right (higher address) sliding compaction.
 //
 // There are four phases of the collection.
 //
@@ -740,80 +740,75 @@ class BitBlockUpdateClosure: public ParMarkBitMapClosure {
 //      - move the objects to their destination
 //      - update some references and reinitialize some variables
 //
-// These three phases are invoked in PSParallelCompact::invoke_no_policy().
+// These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
-// The marking phase is implemented in PSParallelCompact::marking_phase()
+// marking phase is implemented in PSParallelCompact::marking_phase() and does a
-// and does a complete marking of the heap.
+// complete marking of the heap.  The summary phase is implemented in
-// The summary phase is implemented in PSParallelCompact::summary_phase().
+// PSParallelCompact::summary_phase().  The move and update phase is implemented
-// The move and update phase is implemented in PSParallelCompact::compact().
+// in PSParallelCompact::compact().
 //
-// A space that is being collected is divided into chunks and with
+// A space that is being collected is divided into regions and with each region
-// each chunk is associated an object of type ParallelCompactData.
+// is associated an object of type ParallelCompactData.  Each region is of a
-// Each chunk is of a fixed size and typically will contain more than
+// fixed size and typically will contain more than 1 object and may have parts
-// 1 object and may have parts of objects at the front and back of the
+// of objects at the front and back of the region.
-// chunk.
 //
-// chunk            -----+---------------------+----------
+// region            -----+---------------------+----------
 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 //
-// The marking phase does a complete marking of all live objects in the
+// The marking phase does a complete marking of all live objects in the heap.
-// heap.  The marking also compiles the size of the data for
+// The marking also compiles the size of the data for all live objects covered
-// all live objects covered by the chunk.  This size includes the
+// by the region.  This size includes the part of any live object spanning onto
-// part of any live object spanning onto the chunk (part of AAA
+// the region (part of AAA if it is live) from the front, all live objects
-// if it is live) from the front, all live objects contained in the chunk
+// contained in the region (BBB and/or CCC if they are live), and the part of
-// (BBB and/or CCC if they are live), and the part of any live objects
+// any live objects covered by the region that extends off the region (part of
-// covered by the chunk that extends off the chunk (part of DDD if it is
+// DDD if it is live).  The marking phase uses multiple GC threads and marking
-// live).  The marking phase uses multiple GC threads and marking is
+// is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
-// done in a bit array of type ParMarkBitMap.  The marking of the
+// done atomically as is the accumulation of the size of the live objects
-// bit map is done atomically as is the accumulation of the size of the
+// covered by a region.
-// live objects covered by a chunk.
 //
-// The summary phase calculates the total live data to the left of
+// The summary phase calculates the total live data to the left of each region
-// each chunk XXX.  Based on that total and the bottom of the space,
+// XXX.  Based on that total and the bottom of the space, it can calculate the
-// it can calculate the starting location of the live data in XXX.
+// starting location of the live data in XXX.  The summary phase calculates for
-// The summary phase calculates for each chunk XXX quantites such as
+// each region XXX quantites such as
 //
-//      - the amount of live data at the beginning of a chunk from an object
+//      - the amount of live data at the beginning of a region from an object
-//      entering the chunk.
+//        entering the region.
-//      - the location of the first live data on the chunk
+//      - the location of the first live data on the region
-//      - a count of the number of chunks receiving live data from XXX.
+//      - 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
+// calculates the dense prefix for the compaction.  The dense prefix is a
-// is a portion at the beginning of the space that is not moved.  The
+// portion at the beginning of the space that is not moved.  The objects in the
-// objects in the dense prefix do need to have their object references
+// dense prefix do need to have their object references updated.  See method
-// updated.  See method summarize_dense_prefix().
+// summarize_dense_prefix().
 //
 // The summary phase is done using 1 GC thread.
 //
-// The compaction phase moves objects to their new location and updates
+// The compaction phase moves objects to their new location and updates all
-// all references in the object.
+// references in the object.
 //
-// A current exception is that objects that cross a chunk boundary
+// A current exception is that objects that cross a region boundary are moved
-// are moved but do not have their references updated.  References are
+// but do not have their references updated.  References are not updated because
-// not updated because it cannot easily be determined if the klass
+// it cannot easily be determined if the klass pointer KKK for the object AAA
-// pointer KKK for the object AAA has been updated.  KKK likely resides
+// has been updated.  KKK likely resides in a region to the left of the region
-// in a chunk to the left of the chunk containing AAA.  These AAA's
+// containing AAA.  These AAA's have there references updated at the end in a
-// have there references updated at the end in a clean up phase.
+// clean up phase.  See the method PSParallelCompact::update_deferred_objects().
-// See the method PSParallelCompact::update_deferred_objects().  An
+// An alternate strategy is being investigated for this deferral of updating.
-// 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 @@ class PSParallelCompact : AllStatic {
   // 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.
+  // region in the space that is not completely live.
-  static ChunkData* dead_wood_limit_chunk(const ChunkData* beg,
+  static RegionData* dead_wood_limit_region(const RegionData* beg,
-                                          const ChunkData* end,
+                                            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,
+  static RegionData* first_dead_space_region(const RegionData* beg,
-                                           const ChunkData* end);
+                                             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 @@ class PSParallelCompact : AllStatic {
   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
+  // Return true if dead space crosses onto the specified Region; bit must be
-  // bit index corresponding to the first word of the Chunk.
+  // the bit index corresponding to the first word of the Region.
-  static inline bool dead_space_crosses_boundary(const ChunkData* chunk,
+  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 @@ class PSParallelCompact : AllStatic {
   static void compact_perm(ParCompactionManager* cm);
   static void compact();
 
-  // Add available chunks to the stack and draining tasks to the task queue.
+  // Add available regions to the stack and draining tasks to the task queue.
-  static void enqueue_chunk_draining_tasks(GCTaskQueue* q,
+  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.
+  // Add region stealing tasks to the task queue.
-  static void enqueue_chunk_stealing_tasks(
+  static void enqueue_region_stealing_tasks(
                                        GCTaskQueue* q,
                                        ParallelTaskTerminator* terminator_ptr,
                                        uint parallel_gc_threads);
@@ -1154,56 +1149,56 @@ class PSParallelCompact : AllStatic {
   // 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,
+  static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
-                                           size_t chunk_start_index,
+                                            size_t region_start_index,
-                                           size_t chunk_end_index,
+                                            size_t region_end_index,
                                             idx_t exiting_object_offset,
-                                           idx_t chunk_offset_start,
+                                            idx_t region_offset_start,
-                                           idx_t chunk_offset_end);
+                                            idx_t region_offset_end);
 
-  // Update a chunk in the dense prefix.  For each live object
+  // Update a region in the dense prefix.  For each live object
-  // in the chunk, update it's interior references.  For each
+  // 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
+  // of a region range will be filled to the start of the next
-  // live object regardless of the chunk_index_end.  None of the
+  // 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 region_index_start,
-                                                  size_t chunk_index_end);
+                                                  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
+  // Determine the next source region, set closure.source() to the start of the
-  // new chunk return the chunk index.  Parameter end_addr is the address one
+  // 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,
+  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
+  // Decrement the destination count for each non-empty source region in the
-  // range [beg_chunk, chunk(chunk_align_up(end_addr))).
+  // 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.
+  // Fill a region, copying objects from one or more source regions.
-  static void fill_chunk(ParCompactionManager* cm, size_t chunk_idx);
+  static void fill_region(ParCompactionManager* cm, size_t region_idx);
-  static void fill_and_update_chunk(ParCompactionManager* cm, size_t chunk) {
+  static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
-    fill_chunk(cm, chunk);
+    fill_region(cm, region);
   }
 
   // Update the deferred objects in the space.
@@ -1259,7 +1254,7 @@ class PSParallelCompact : AllStatic {
 #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 @@ class PSParallelCompact : AllStatic {
 #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 double PSParallelCompact::normal_distribution(double density) {
 }
 
 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(bit > 0, "cannot call this for the first bit/region");
-  assert(_summary_data.chunk_to_addr(chunk) == _mark_bitmap.bit_to_addr(bit),
+  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,
+  // onto the region, (2) an object does not start at the beginning of the
-  // and (3) an object does not end at the end of the prior chunk.
+  // region, and (3) an object does not end at the end of the prior region.
-  return chunk->partial_obj_size() == 0 &&
+  return region->partial_obj_size() == 0 &&
     !_mark_bitmap.is_obj_beg(bit) &&
     !_mark_bitmap.is_obj_end(bit - 1);
 }

hotspot/src/share/vm/runtime/globals.hpp

@@ -1157,9 +1157,9 @@ class CommandLineFlags {
           "In the Parallel Old garbage collector use parallel dense"        \
           " prefix update")                                                 \
                                                                             \
-  develop(bool, UseParallelOldGCChunkPointerCalc, true,                     \
+  develop(bool, UseParallelOldGCRegionPointerCalc, true,                    \
-          "In the Parallel Old garbage collector use chucks to calculate"   \
+          "In the Parallel Old garbage collector use regions to calculate"  \
-          " new object locations")                                          \
+          "new object locations")                                           \
                                                                             \
   product(uintx, HeapMaximumCompactionInterval, 20,                         \
           "How often should we maximally compact the heap (not allowing "   \
@@ -1195,8 +1195,8 @@ class CommandLineFlags {
   develop(bool, ParallelOldMTUnsafeUpdateLiveData, false,                   \
           "Use the Parallel Old MT unsafe in update of live size")          \
                                                                             \
-  develop(bool, TraceChunkTasksQueuing, false,                              \
+  develop(bool, TraceRegionTasksQueuing, false,                             \
-          "Trace the queuing of the chunk tasks")                           \
+          "Trace the queuing of the region tasks")                          \
                                                                             \
   product(uintx, ParallelMarkingThreads, 0,                                 \
           "Number of marking threads concurrent gc will use")               \

hotspot/src/share/vm/utilities/taskqueue.cpp

@@ -109,72 +109,72 @@ void ParallelTaskTerminator::reset_for_reuse() {
   }
 }
 
-bool ChunkTaskQueueWithOverflow::is_empty() {
+bool RegionTaskQueueWithOverflow::is_empty() {
-  return (_chunk_queue.size() == 0) &&
+  return (_region_queue.size() == 0) &&
          (_overflow_stack->length() == 0);
 }
 
-bool ChunkTaskQueueWithOverflow::stealable_is_empty() {
+bool RegionTaskQueueWithOverflow::stealable_is_empty() {
-  return _chunk_queue.size() == 0;
+  return _region_queue.size() == 0;
 }
 
-bool ChunkTaskQueueWithOverflow::overflow_is_empty() {
+bool RegionTaskQueueWithOverflow::overflow_is_empty() {
   return _overflow_stack->length() == 0;
 }
 
-void ChunkTaskQueueWithOverflow::initialize() {
+void RegionTaskQueueWithOverflow::initialize() {
-  _chunk_queue.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) {
+void RegionTaskQueueWithOverflow::save(RegionTask t) {
-  if (TraceChunkTasksQueuing && Verbose) {
+  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 RegionTaskQueueWithOverflow::retrieve(RegionTask& region_task) {
-  bool result = retrieve_from_overflow(chunk_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(
+bool RegionTaskQueueWithOverflow::retrieve_from_stealable_queue(
-                                   ChunkTask& chunk_task) {
+                                   RegionTask& region_task) {
-  bool result = _chunk_queue.pop_local(chunk_task);
+  bool result = _region_queue.pop_local(region_task);
-  if (TraceChunkTasksQueuing && Verbose) {
+  if (TraceRegionTasksQueuing && Verbose) {
-    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
   }
   return result;
 }
 
-bool ChunkTaskQueueWithOverflow::retrieve_from_overflow(
+bool
-                                        ChunkTask& chunk_task) {
+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) {
+  if (TraceRegionTasksQueuing && Verbose) {
-    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, chunk_task);
+    gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
   }
   return result;
 }

hotspot/src/share/vm/utilities/taskqueue.hpp

@@ -557,32 +557,32 @@ class StarTask {
 typedef GenericTaskQueue<StarTask>     OopStarTaskQueue;
 typedef GenericTaskQueueSet<StarTask>  OopStarTaskQueueSet;
 
-typedef size_t ChunkTask;  // index for chunk
+typedef size_t RegionTask;  // index for region
-typedef GenericTaskQueue<ChunkTask>    ChunkTaskQueue;
+typedef GenericTaskQueue<RegionTask>    RegionTaskQueue;
-typedef GenericTaskQueueSet<ChunkTask> ChunkTaskQueueSet;
+typedef GenericTaskQueueSet<RegionTask> RegionTaskQueueSet;
 
-class ChunkTaskQueueWithOverflow: public CHeapObj {
+class RegionTaskQueueWithOverflow: public CHeapObj {
  protected:
-  ChunkTaskQueue              _chunk_queue;
+  RegionTaskQueue              _region_queue;
-  GrowableArray<ChunkTask>*   _overflow_stack;
+  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(); }
+  juint stealable_size() { return _region_queue.size(); }
-  ChunkTaskQueue* task_queue() { return &_chunk_queue; }
+  RegionTaskQueue* task_queue() { return &_region_queue; }
 };
 
-#define USE_ChunkTaskQueueWithOverflow
+#define USE_RegionTaskQueueWithOverflow