--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Fri Feb 26 13:02:30 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Fri Feb 26 13:02:30 2016 +0100
@@ -4398,6 +4398,8 @@
   { }
 
   void work(uint worker_id) {
+    G1GCParPhaseTimesTracker x(_g1h->g1_policy()->phase_times(), G1GCPhaseTimes::PreserveCMReferents, worker_id);
+
     ResourceMark rm;
     HandleMark   hm;
 
@@ -4461,13 +4463,8 @@
   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
 }
 
-// Weak Reference processing during an evacuation pause (part 1).
-void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
-  double ref_proc_start = os::elapsedTime();
-
-  ReferenceProcessor* rp = _ref_processor_stw;
-  assert(rp->discovery_enabled(), "should have been enabled");
-
+void G1CollectedHeap::preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states) {
+  double preserve_cm_referents_start = os::elapsedTime();
   // Any reference objects, in the collection set, that were 'discovered'
   // by the CM ref processor should have already been copied (either by
   // applying the external root copy closure to the discovered lists, or
@@ -4495,9 +4492,18 @@
                                                  per_thread_states,
                                                  no_of_gc_workers,
                                                  _task_queues);
-
   workers()->run_task(&keep_cm_referents);
 
+  g1_policy()->phase_times()->record_preserve_cm_referents_time_ms((os::elapsedTime() - preserve_cm_referents_start) * 1000.0);
+}
+
+// Weak Reference processing during an evacuation pause (part 1).
+void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
+  double ref_proc_start = os::elapsedTime();
+
+  ReferenceProcessor* rp = _ref_processor_stw;
+  assert(rp->discovery_enabled(), "should have been enabled");
+
   // Closure to test whether a referent is alive.
   G1STWIsAliveClosure is_alive(this);
 
@@ -4529,6 +4535,8 @@
                                               NULL,
                                               _gc_timer_stw);
   } else {
+    uint no_of_gc_workers = workers()->active_workers();
+
     // Parallel reference processing
     assert(rp->num_q() == no_of_gc_workers, "sanity");
     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
@@ -4644,6 +4652,7 @@
   // objects (and their reachable sub-graphs) that were
   // not copied during the pause.
   if (g1_policy()->should_process_references()) {
+    preserve_cm_referents(per_thread_states);
     process_discovered_references(per_thread_states);
   } else {
     ref_processor_stw()->verify_no_references_recorded();

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Fri Feb 26 13:02:30 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Fri Feb 26 13:02:30 2016 +0100
@@ -511,6 +511,9 @@
   // allocated block, or else "NULL".
   HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
 
+  // Preserve any referents discovered by concurrent marking that have not yet been
+  // copied by the STW pause.
+  void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
   // Process any reference objects discovered during
   // an incremental evacuation pause.
   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);

--- a/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.cpp	Fri Feb 26 13:02:30 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.cpp	Fri Feb 26 13:02:30 2016 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -129,6 +129,8 @@
   _gc_par_phases[RedirtyCards] = new WorkerDataArray<double>(max_gc_threads, "Parallel Redirty:", true, 3);
   _redirtied_cards = new WorkerDataArray<size_t>(max_gc_threads, "Redirtied Cards:", true, 3);
   _gc_par_phases[RedirtyCards]->link_thread_work_items(_redirtied_cards);
+
+  _gc_par_phases[PreserveCMReferents] = new WorkerDataArray<double>(max_gc_threads, "Parallel Preserve CM Refs:", true, 3);
 }
 
 void G1GCPhaseTimes::note_gc_start(uint active_gc_threads) {
@@ -392,10 +394,12 @@
   print_stats(Indents[2], "Choose CSet",
     (_recorded_young_cset_choice_time_ms +
     _recorded_non_young_cset_choice_time_ms));
+  print_stats(Indents[2], "Preserve CM Refs", _recorded_preserve_cm_referents_time_ms);
   print_stats(Indents[2], "Ref Proc", _cur_ref_proc_time_ms);
   print_stats(Indents[2], "Ref Enq", _cur_ref_enq_time_ms);
   print_stats(Indents[2], "Redirty Cards", _recorded_redirty_logged_cards_time_ms);
   par_phase_printer.print(RedirtyCards);
+  par_phase_printer.print(PreserveCMReferents);
   if (G1EagerReclaimHumongousObjects) {
     print_stats(Indents[2], "Humongous Register", _cur_fast_reclaim_humongous_register_time_ms);
 

--- a/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.hpp	Fri Feb 26 13:02:30 2016 +0100
+++ b/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.hpp	Fri Feb 26 13:02:30 2016 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -69,6 +69,7 @@
     StringDedupQueueFixup,
     StringDedupTableFixup,
     RedirtyCards,
+    PreserveCMReferents,
     GCParPhasesSentinel
   };
 
@@ -108,6 +109,8 @@
 
   double _recorded_redirty_logged_cards_time_ms;
 
+  double _recorded_preserve_cm_referents_time_ms;
+
   double _recorded_young_free_cset_time_ms;
   double _recorded_non_young_free_cset_time_ms;
 
@@ -234,6 +237,10 @@
     _recorded_redirty_logged_cards_time_ms = time_ms;
   }
 
+  void record_preserve_cm_referents_time_ms(double time_ms) {
+    _recorded_preserve_cm_referents_time_ms = time_ms;
+  }
+
   void record_cur_collection_start_sec(double time_ms) {
     _cur_collection_start_sec = time_ms;
   }

--- a/hotspot/test/gc/g1/TestGCLogMessages.java	Fri Feb 26 13:02:30 2016 +0100
+++ b/hotspot/test/gc/g1/TestGCLogMessages.java	Fri Feb 26 13:02:30 2016 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,7 +23,7 @@
 
 /*
  * @test TestGCLogMessages
- * @bug 8035406 8027295 8035398 8019342 8027959 8048179 8027962 8069330
+ * @bug 8035406 8027295 8035398 8019342 8027959 8048179 8027962 8069330 8076463
  * @summary Ensure the output for a minor GC with G1
  * includes the expected necessary messages.
  * @key gc
@@ -86,6 +86,8 @@
         // Humongous Eager Reclaim
         new LogMessageWithLevel("Humongous Reclaim", Level.DEBUG),
         new LogMessageWithLevel("Humongous Register", Level.DEBUG),
+        // Preserve CM Referents
+        new LogMessageWithLevel("Preserve CM Refs", Level.DEBUG),
     };
 
     void checkMessagesAtLevel(OutputAnalyzer output, LogMessageWithLevel messages[], Level level) throws Exception {