changeset 5004:8695497c703c

6412968: CMS: Long initial mark pauses 6990419: CMS: Remaining work for 6572569: consistently skewed work distribution in (long) re-mark pauses Summary: Backport of fixes for 6412968 and 6990419 Reviewed-by: jmasa
author poonam
date Mon, 17 Feb 2014 18:14:21 -0800
parents 63bf5b308fc7
children d788d77bc087
files src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp src/share/vm/memory/defNewGeneration.cpp src/share/vm/memory/generation.hpp src/share/vm/memory/sharedHeap.cpp src/share/vm/runtime/globals.hpp
diffstat 7 files changed, 273 insertions(+), 52 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp	Mon Feb 17 18:14:21 2014 -0800
@@ -58,8 +58,22 @@
   MarkRefsIntoClosure(MemRegion span, CMSBitMap* bitMap);
   virtual void do_oop(oop* p);
   virtual void do_oop(narrowOop* p);
-  inline void do_oop_nv(oop* p)       { MarkRefsIntoClosure::do_oop_work(p); }
-  inline void do_oop_nv(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); }
+
+  Prefetch::style prefetch_style() {
+    return Prefetch::do_read;
+  }
+};
+
+class Par_MarkRefsIntoClosure: public OopsInGenClosure {
+ private:
+  const MemRegion _span;
+  CMSBitMap*      _bitMap;
+ protected:
+  DO_OOP_WORK_DEFN
+ public:
+  Par_MarkRefsIntoClosure(MemRegion span, CMSBitMap* bitMap);
+  virtual void do_oop(oop* p);
+  virtual void do_oop(narrowOop* p);
   bool do_header() { return true; }
   Prefetch::style prefetch_style() {
     return Prefetch::do_read;
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Mon Feb 17 18:14:21 2014 -0800
@@ -575,6 +575,7 @@
   _restart_addr(NULL),
   _overflow_list(NULL),
   _stats(cmsGen),
+  _eden_chunk_lock(new Mutex(Mutex::leaf + 1, "CMS_eden_chunk_lock", true)),
   _eden_chunk_array(NULL),     // may be set in ctor body
   _eden_chunk_capacity(0),     // -- ditto --
   _eden_chunk_index(0),        // -- ditto --
@@ -754,7 +755,7 @@
   assert(_eden_chunk_array != NULL || _eden_chunk_capacity == 0, "Error");
 
   // Support for parallelizing survivor space rescan
-  if (CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) {
+  if ((CMSParallelRemarkEnabled && CMSParallelSurvivorRemarkEnabled) || CMSParallelInitialMarkEnabled) {
     const size_t max_plab_samples =
       ((DefNewGeneration*)_young_gen)->max_survivor_size()/MinTLABSize;
 
@@ -2136,6 +2137,39 @@
 }
 
 
+void CMSCollector::print_eden_and_survivor_chunk_arrays() {
+  DefNewGeneration* dng = _young_gen->as_DefNewGeneration();
+  EdenSpace* eden_space = dng->eden();
+  ContiguousSpace* from_space = dng->from();
+  ContiguousSpace* to_space   = dng->to();
+  // Eden
+  if (_eden_chunk_array != NULL) {
+    gclog_or_tty->print_cr("eden " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")",
+                           eden_space->bottom(), eden_space->top(),
+                           eden_space->end(), eden_space->capacity());
+    gclog_or_tty->print_cr("_eden_chunk_index=" SIZE_FORMAT ", "
+                           "_eden_chunk_capacity=" SIZE_FORMAT,
+                           _eden_chunk_index, _eden_chunk_capacity);
+    for (size_t i = 0; i < _eden_chunk_index; i++) {
+      gclog_or_tty->print_cr("_eden_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT,
+                             i, _eden_chunk_array[i]);
+    }
+  }
+  // Survivor
+  if (_survivor_chunk_array != NULL) {
+    gclog_or_tty->print_cr("survivor " PTR_FORMAT "-" PTR_FORMAT "-" PTR_FORMAT "(" SIZE_FORMAT ")",
+                           from_space->bottom(), from_space->top(),
+                           from_space->end(), from_space->capacity());
+    gclog_or_tty->print_cr("_survivor_chunk_index=" SIZE_FORMAT ", "
+                           "_survivor_chunk_capacity=" SIZE_FORMAT,
+                           _survivor_chunk_index, _survivor_chunk_capacity);
+    for (size_t i = 0; i < _survivor_chunk_index; i++) {
+      gclog_or_tty->print_cr("_survivor_chunk_array[" SIZE_FORMAT "]=" PTR_FORMAT,
+                             i, _survivor_chunk_array[i]);
+    }
+  }
+}
+
 void CMSCollector::getFreelistLocks() const {
   // Get locks for all free lists in all generations that this
   // collector is responsible for
@@ -3526,6 +3560,31 @@
 
 // CMS work
 
+// The common parts of CMSParInitialMarkTask and CMSParRemarkTask.
+class CMSParMarkTask : public AbstractGangTask {
+ protected:
+  CMSCollector*     _collector;
+  int               _n_workers;
+  CMSParMarkTask(const char* name, CMSCollector* collector, int n_workers) :
+      AbstractGangTask(name),
+      _collector(collector),
+      _n_workers(n_workers) {}
+  // Work method in support of parallel rescan ... of young gen spaces
+  void do_young_space_rescan(uint worker_id, OopsInGenClosure* cl,
+                             ContiguousSpace* space,
+                             HeapWord** chunk_array, size_t chunk_top);
+  void work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl);
+};
+
+// Parallel initial mark task
+class CMSParInitialMarkTask: public CMSParMarkTask {
+ public:
+  CMSParInitialMarkTask(CMSCollector* collector, int n_workers) :
+      CMSParMarkTask("Scan roots and young gen for initial mark in parallel",
+                     collector, n_workers) {}
+  void work(uint worker_id);
+};
+
 // Checkpoint the roots into this generation from outside
 // this generation. [Note this initial checkpoint need only
 // be approximate -- we'll do a catch up phase subsequently.]
@@ -3615,20 +3674,42 @@
   // weak reference processing has not started yet.
   ref_processor()->set_enqueuing_is_done(false);
 
+  if (CMSPrintEdenSurvivorChunks) {
+    print_eden_and_survivor_chunk_arrays();
+  }
+
   {
     // This is not needed. DEBUG_ONLY(RememberKlassesChecker imx(true);)
     COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;)
-    gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
-    gch->gen_process_strong_roots(_cmsGen->level(),
-                                  true,   // younger gens are roots
-                                  true,   // activate StrongRootsScope
-                                  true,   // collecting perm gen
-                                  SharedHeap::ScanningOption(roots_scanning_options()),
-                                  &notOlder,
-                                  true,   // walk all of code cache if (so & SO_CodeCache)
-                                  NULL);
-  }
-
+    if (CMSParallelInitialMarkEnabled && CollectedHeap::use_parallel_gc_threads()) {
+      // The parallel version.
+      FlexibleWorkGang* workers = gch->workers();
+      assert(workers != NULL, "Need parallel worker threads.");
+      int n_workers = workers->active_workers();
+      CMSParInitialMarkTask tsk(this, n_workers);
+      gch->set_par_threads(n_workers);
+      initialize_sequential_subtasks_for_young_gen_rescan(n_workers);
+      if (n_workers > 1) {
+        GenCollectedHeap::StrongRootsScope srs(gch);
+        workers->run_task(&tsk);
+      } else {
+        GenCollectedHeap::StrongRootsScope srs(gch);
+        tsk.work(0);
+      }
+      gch->set_par_threads(0);
+    } else {
+      // The serial version.
+      gch->rem_set()->prepare_for_younger_refs_iterate(false); // Not parallel.
+      gch->gen_process_strong_roots(_cmsGen->level(),
+                                    true,   // younger gens are roots
+                                    true,   // activate StrongRootsScope
+                                    true,   // collecting perm gen
+                                    SharedHeap::ScanningOption(roots_scanning_options()),
+                                    &notOlder,
+                                    true,   // walk all of code cache if (so & SO_CodeCache)
+                                    NULL);
+    }
+  }
   // Clear mod-union table; it will be dirtied in the prologue of
   // CMS generation per each younger generation collection.
 
@@ -4410,7 +4491,9 @@
   verify_overflow_empty();
   _abort_preclean = false;
   if (CMSPrecleaningEnabled) {
-    _eden_chunk_index = 0;
+    if (!CMSEdenChunksRecordAlways) {
+      _eden_chunk_index = 0;
+    }
     size_t used = get_eden_used();
     size_t capacity = get_eden_capacity();
     // Don't start sampling unless we will get sufficiently
@@ -4519,7 +4602,9 @@
   if (!_start_sampling) {
     return;
   }
-  if (_eden_chunk_array) {
+  // When CMSEdenChunksRecordAlways is true, the eden chunk array
+  // is populated by the young generation.
+  if (_eden_chunk_array != NULL && !CMSEdenChunksRecordAlways) {
     if (_eden_chunk_index < _eden_chunk_capacity) {
       _eden_chunk_array[_eden_chunk_index] = *_top_addr;   // take sample
       assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr,
@@ -4996,6 +5081,10 @@
     // Update the saved marks which may affect the root scans.
     gch->save_marks();
 
+    if (CMSPrintEdenSurvivorChunks) {
+      print_eden_and_survivor_chunk_arrays();
+    }
+
     {
       COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact;)
 
@@ -5103,10 +5192,51 @@
   }
 }
 
+void CMSParInitialMarkTask::work(uint worker_id) {
+  elapsedTimer _timer;
+  ResourceMark rm;
+  HandleMark   hm;
+
+  // ---------- scan from roots --------------
+  _timer.start();
+  GenCollectedHeap* gch = GenCollectedHeap::heap();
+  Par_MarkRefsIntoClosure par_mri_cl(_collector->_span, &(_collector->_markBitMap));
+
+  // ---------- young gen roots --------------
+  {
+    work_on_young_gen_roots(worker_id, &par_mri_cl);
+    _timer.stop();
+    if (PrintCMSStatistics != 0) {
+      gclog_or_tty->print_cr(
+        "Finished young gen initial mark scan work in %dth thread: %3.3f sec",
+        worker_id, _timer.seconds());
+    }
+  }
+
+  // ---------- remaining roots --------------
+  _timer.reset();
+  _timer.start();
+  gch->gen_process_strong_roots(_collector->_cmsGen->level(),
+                                false,     // yg was scanned above
+                                false,     // this is parallel code
+                                true,      // collecting perm gen
+                                SharedHeap::ScanningOption(_collector->CMSCollector::roots_scanning_options()),
+                                &par_mri_cl,
+                                true,   // walk all of code cache if (so & SO_CodeCache)
+                                NULL);
+  assert(_collector->should_unload_classes()
+         || (_collector->CMSCollector::roots_scanning_options() & SharedHeap::SO_CodeCache),
+         "if we didn't scan the code cache, we have to be ready to drop nmethods with expired weak oops");
+  _timer.stop();
+  if (PrintCMSStatistics != 0) {
+    gclog_or_tty->print_cr(
+      "Finished remaining root initial mark scan work in %dth thread: %3.3f sec",
+      worker_id, _timer.seconds());
+  }
+}
+
 // Parallel remark task
-class CMSParRemarkTask: public AbstractGangTask {
-  CMSCollector* _collector;
-  int           _n_workers;
+class CMSParRemarkTask: public CMSParMarkTask {
   CompactibleFreeListSpace* _cms_space;
   CompactibleFreeListSpace* _perm_space;
 
@@ -5122,10 +5252,9 @@
                    CompactibleFreeListSpace* perm_space,
                    int n_workers, FlexibleWorkGang* workers,
                    OopTaskQueueSet* task_queues):
-    AbstractGangTask("Rescan roots and grey objects in parallel"),
-    _collector(collector),
+    CMSParMarkTask("Rescan roots and grey objects in parallel",
+                   collector, n_workers),
     _cms_space(cms_space), _perm_space(perm_space),
-    _n_workers(n_workers),
     _task_queues(task_queues),
     _term(n_workers, task_queues) { }
 
@@ -5139,11 +5268,6 @@
   void work(uint worker_id);
 
  private:
-  // Work method in support of parallel rescan ... of young gen spaces
-  void do_young_space_rescan(int i, Par_MarkRefsIntoAndScanClosure* cl,
-                             ContiguousSpace* space,
-                             HeapWord** chunk_array, size_t chunk_top);
-
   // ... of  dirty cards in old space
   void do_dirty_card_rescan_tasks(CompactibleFreeListSpace* sp, int i,
                                   Par_MarkRefsIntoAndScanClosure* cl);
@@ -5152,6 +5276,25 @@
   void do_work_steal(int i, Par_MarkRefsIntoAndScanClosure* cl, int* seed);
 };
 
+void CMSParMarkTask::work_on_young_gen_roots(uint worker_id, OopsInGenClosure* cl) {
+  DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration();
+  EdenSpace* eden_space = dng->eden();
+  ContiguousSpace* from_space = dng->from();
+  ContiguousSpace* to_space   = dng->to();
+
+  HeapWord** eca = _collector->_eden_chunk_array;
+  size_t     ect = _collector->_eden_chunk_index;
+  HeapWord** sca = _collector->_survivor_chunk_array;
+  size_t     sct = _collector->_survivor_chunk_index;
+
+  assert(ect <= _collector->_eden_chunk_capacity, "out of bounds");
+  assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds");
+
+  do_young_space_rescan(worker_id, cl, to_space, NULL, 0);
+  do_young_space_rescan(worker_id, cl, from_space, sca, sct);
+  do_young_space_rescan(worker_id, cl, eden_space, eca, ect);
+}
+
 // work_queue(i) is passed to the closure
 // Par_MarkRefsIntoAndScanClosure.  The "i" parameter
 // also is passed to do_dirty_card_rescan_tasks() and to
@@ -5176,23 +5319,7 @@
   // work first.
   // ---------- young gen roots --------------
   {
-    DefNewGeneration* dng = _collector->_young_gen->as_DefNewGeneration();
-    EdenSpace* eden_space = dng->eden();
-    ContiguousSpace* from_space = dng->from();
-    ContiguousSpace* to_space   = dng->to();
-
-    HeapWord** eca = _collector->_eden_chunk_array;
-    size_t     ect = _collector->_eden_chunk_index;
-    HeapWord** sca = _collector->_survivor_chunk_array;
-    size_t     sct = _collector->_survivor_chunk_index;
-
-    assert(ect <= _collector->_eden_chunk_capacity, "out of bounds");
-    assert(sct <= _collector->_survivor_chunk_capacity, "out of bounds");
-
-    do_young_space_rescan(worker_id, &par_mrias_cl, to_space, NULL, 0);
-    do_young_space_rescan(worker_id, &par_mrias_cl, from_space, sca, sct);
-    do_young_space_rescan(worker_id, &par_mrias_cl, eden_space, eca, ect);
-
+    work_on_young_gen_roots(worker_id, &par_mrias_cl);
     _timer.stop();
     if (PrintCMSStatistics != 0) {
       gclog_or_tty->print_cr(
@@ -5253,8 +5380,8 @@
 
 // Note that parameter "i" is not used.
 void
-CMSParRemarkTask::do_young_space_rescan(int i,
-  Par_MarkRefsIntoAndScanClosure* cl, ContiguousSpace* space,
+CMSParMarkTask::do_young_space_rescan(uint worker_id,
+  OopsInGenClosure* cl, ContiguousSpace* space,
   HeapWord** chunk_array, size_t chunk_top) {
   // Until all tasks completed:
   // . claim an unclaimed task
@@ -5450,6 +5577,32 @@
          "Else our work is not yet done");
 }
 
+// Record object boundaries in _eden_chunk_array by sampling the eden
+// top in the slow-path eden object allocation code path and record
+// the boundaries, if CMSEdenChunksRecordAlways is true. If
+// CMSEdenChunksRecordAlways is false, we use the other asynchronous
+// sampling in sample_eden() that activates during the part of the
+// preclean phase.
+void CMSCollector::sample_eden_chunk() {
+  if (CMSEdenChunksRecordAlways && _eden_chunk_array != NULL) {
+    if (_eden_chunk_lock->try_lock()) {
+      // Record a sample. This is the critical section. The contents
+      // of the _eden_chunk_array have to be non-decreasing in the
+      // address order.
+      _eden_chunk_array[_eden_chunk_index] = *_top_addr;
+      assert(_eden_chunk_array[_eden_chunk_index] <= *_end_addr,
+             "Unexpected state of Eden");
+      if (_eden_chunk_index == 0 ||
+          ((_eden_chunk_array[_eden_chunk_index] > _eden_chunk_array[_eden_chunk_index-1]) &&
+           (pointer_delta(_eden_chunk_array[_eden_chunk_index],
+                          _eden_chunk_array[_eden_chunk_index-1]) >= CMSSamplingGrain))) {
+        _eden_chunk_index++;  // commit sample
+      }
+      _eden_chunk_lock->unlock();
+    }
+  }
+}
+
 // Return a thread-local PLAB recording array, as appropriate.
 void* CMSCollector::get_data_recorder(int thr_num) {
   if (_survivor_plab_array != NULL &&
@@ -5473,12 +5626,13 @@
 
 // Merge the per-thread plab arrays into the global survivor chunk
 // array which will provide the partitioning of the survivor space
-// for CMS rescan.
+// for CMS initial scan and rescan.
 void CMSCollector::merge_survivor_plab_arrays(ContiguousSpace* surv,
                                               int no_of_gc_threads) {
   assert(_survivor_plab_array  != NULL, "Error");
   assert(_survivor_chunk_array != NULL, "Error");
-  assert(_collectorState == FinalMarking, "Error");
+  assert(_collectorState == FinalMarking ||
+         (CMSParallelInitialMarkEnabled && _collectorState == InitialMarking), "Error");
   for (int j = 0; j < no_of_gc_threads; j++) {
     _cursor[j] = 0;
   }
@@ -5541,7 +5695,7 @@
 }
 
 // Set up the space's par_seq_tasks structure for work claiming
-// for parallel rescan of young gen.
+// for parallel initial scan and rescan of young gen.
 // See ParRescanTask where this is currently used.
 void
 CMSCollector::
@@ -6691,6 +6845,28 @@
 void MarkRefsIntoClosure::do_oop(oop* p)       { MarkRefsIntoClosure::do_oop_work(p); }
 void MarkRefsIntoClosure::do_oop(narrowOop* p) { MarkRefsIntoClosure::do_oop_work(p); }
 
+Par_MarkRefsIntoClosure::Par_MarkRefsIntoClosure(
+  MemRegion span, CMSBitMap* bitMap):
+    _span(span),
+    _bitMap(bitMap)
+{
+    assert(_ref_processor == NULL, "deliberately left NULL");
+    assert(_bitMap->covers(_span), "_bitMap/_span mismatch");
+}
+
+void Par_MarkRefsIntoClosure::do_oop(oop obj) {
+  // if p points into _span, then mark corresponding bit in _markBitMap
+  assert(obj->is_oop(), "expected an oop");
+  HeapWord* addr = (HeapWord*)obj;
+  if (_span.contains(addr)) {
+    // this should be made more efficient
+    _bitMap->par_mark(addr);
+  }
+}
+
+void Par_MarkRefsIntoClosure::do_oop(oop* p)       { Par_MarkRefsIntoClosure::do_oop_work(p); }
+void Par_MarkRefsIntoClosure::do_oop(narrowOop* p) { Par_MarkRefsIntoClosure::do_oop_work(p); }
+
 // A variant of the above, used for CMS marking verification.
 MarkRefsIntoVerifyClosure::MarkRefsIntoVerifyClosure(
   MemRegion span, CMSBitMap* verification_bm, CMSBitMap* cms_bm):
@@ -9356,7 +9532,6 @@
     return;
   }
 }
-
 // Transfer some number of overflown objects to usual marking
 // stack. Return true if some objects were transferred.
 bool MarkRefsIntoAndScanClosure::take_from_overflow_list() {
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp	Mon Feb 17 18:14:21 2014 -0800
@@ -516,6 +516,8 @@
   friend class ConcurrentMarkSweepThread;
   friend class ConcurrentMarkSweepGeneration;
   friend class CompactibleFreeListSpace;
+  friend class CMSParMarkTask;
+  friend class CMSParInitialMarkTask;
   friend class CMSParRemarkTask;
   friend class CMSConcMarkingTask;
   friend class CMSRefProcTaskProxy;
@@ -752,6 +754,7 @@
   Generation* _young_gen;  // the younger gen
   HeapWord** _top_addr;    // ... Top of Eden
   HeapWord** _end_addr;    // ... End of Eden
+  Mutex*     _eden_chunk_lock;
   HeapWord** _eden_chunk_array; // ... Eden partitioning array
   size_t     _eden_chunk_index; // ... top (exclusive) of array
   size_t     _eden_chunk_capacity;  // ... max entries in array
@@ -953,6 +956,7 @@
 
   // Support for parallel remark of survivor space
   void* get_data_recorder(int thr_num);
+  void sample_eden_chunk();
 
   CMSBitMap* markBitMap()  { return &_markBitMap; }
   void directAllocated(HeapWord* start, size_t size);
@@ -1031,6 +1035,8 @@
 
   // Initialization errors
   bool completed_initialization() { return _completed_initialization; }
+
+  void print_eden_and_survivor_chunk_arrays();
 };
 
 class CMSExpansionCause : public AllStatic  {
@@ -1317,6 +1323,10 @@
     //Delegate to collector
     return collector()->get_data_recorder(thr_num);
   }
+  void sample_eden_chunk() {
+    //Delegate to collector
+    return collector()->sample_eden_chunk();
+  }
 
   // Printing
   const char* name() const;
--- a/src/share/vm/memory/defNewGeneration.cpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/memory/defNewGeneration.cpp	Mon Feb 17 18:14:21 2014 -0800
@@ -1004,6 +1004,9 @@
   // have to use it here, as well.
   HeapWord* result = eden()->par_allocate(word_size);
   if (result != NULL) {
+    if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
+      _next_gen->sample_eden_chunk();
+    }
     return result;
   }
   do {
@@ -1034,13 +1037,19 @@
   // circular dependency at compile time.
   if (result == NULL) {
     result = allocate_from_space(word_size);
+  } else if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
+    _next_gen->sample_eden_chunk();
   }
   return result;
 }
 
 HeapWord* DefNewGeneration::par_allocate(size_t word_size,
                                          bool is_tlab) {
-  return eden()->par_allocate(word_size);
+  HeapWord* res = eden()->par_allocate(word_size);
+  if (CMSEdenChunksRecordAlways && _next_gen != NULL) {
+    _next_gen->sample_eden_chunk();
+  }
+  return res;
 }
 
 void DefNewGeneration::gc_prologue(bool full) {
--- a/src/share/vm/memory/generation.hpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/memory/generation.hpp	Mon Feb 17 18:14:21 2014 -0800
@@ -457,6 +457,7 @@
   // expected to be GC worker thread-local, with the worker index
   // indicated by "thr_num".
   virtual void* get_data_recorder(int thr_num) { return NULL; }
+  virtual void sample_eden_chunk() {}
 
   // Some generations may require some cleanup actions before allowing
   // a verification.
--- a/src/share/vm/memory/sharedHeap.cpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/memory/sharedHeap.cpp	Mon Feb 17 18:14:21 2014 -0800
@@ -64,7 +64,8 @@
   }
   _sh = this;  // ch is static, should be set only once.
   if ((UseParNewGC ||
-      (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
+      (UseConcMarkSweepGC && (CMSParallelInitialMarkEnabled ||
+                              CMSParallelRemarkEnabled)) ||
        UseG1GC) &&
       ParallelGCThreads > 0) {
     _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
--- a/src/share/vm/runtime/globals.hpp	Tue Jan 21 20:05:28 2014 -0800
+++ b/src/share/vm/runtime/globals.hpp	Mon Feb 17 18:14:21 2014 -0800
@@ -1697,6 +1697,9 @@
   product(bool, CMSAbortSemantics, false,                                   \
           "Whether abort-on-overflow semantics is implemented")             \
                                                                             \
+  product(bool, CMSParallelInitialMarkEnabled, false,                       \
+          "Use the parallel initial mark.")                                 \
+                                                                            \
   product(bool, CMSParallelRemarkEnabled, true,                             \
           "Whether parallel remark enabled (only if ParNewGC)")             \
                                                                             \
@@ -1708,6 +1711,14 @@
           "Whether to always record survivor space PLAB bdries"             \
           " (effective only if CMSParallelSurvivorRemarkEnabled)")          \
                                                                             \
+  product(bool, CMSEdenChunksRecordAlways, false,                           \
+          "Whether to always record eden chunks used for "                  \
+          "the parallel initial mark or remark of eden" )                   \
+                                                                            \
+  product(bool, CMSPrintEdenSurvivorChunks, false,                          \
+          "Print the eden and the survivor chunks used for the parallel "   \
+          "initial mark or remark of the eden/survivor spaces")             \
+                                                                            \
   product(bool, CMSConcurrentMTEnabled, true,                               \
           "Whether multi-threaded concurrent work enabled (if ParNewGC)")   \
                                                                             \