--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Wed Aug 09 17:27:42 2017 +0200
@@ -3237,7 +3237,7 @@
         // investigate this in CR 7178365.
         double sample_end_time_sec = os::elapsedTime();
         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
-        size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScannedCards);
+        size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
         g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
 
         evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());

--- a/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.cpp	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.cpp	Wed Aug 09 17:27:42 2017 +0200
@@ -81,14 +81,18 @@
   _gc_par_phases[Other] = new WorkerDataArray<double>(max_gc_threads, "GC Worker Other (ms):");
 
   _scan_rs_scanned_cards = new WorkerDataArray<size_t>(max_gc_threads, "Scanned Cards:");
-  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_scanned_cards, ScannedCards);
+  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_scanned_cards, ScanRSScannedCards);
   _scan_rs_claimed_cards = new WorkerDataArray<size_t>(max_gc_threads, "Claimed Cards:");
-  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_claimed_cards, ClaimedCards);
+  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_claimed_cards, ScanRSClaimedCards);
   _scan_rs_skipped_cards = new WorkerDataArray<size_t>(max_gc_threads, "Skipped Cards:");
-  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_skipped_cards, SkippedCards);
+  _gc_par_phases[ScanRS]->link_thread_work_items(_scan_rs_skipped_cards, ScanRSSkippedCards);
 
   _update_rs_processed_buffers = new WorkerDataArray<size_t>(max_gc_threads, "Processed Buffers:");
-  _gc_par_phases[UpdateRS]->link_thread_work_items(_update_rs_processed_buffers);
+  _gc_par_phases[UpdateRS]->link_thread_work_items(_update_rs_processed_buffers, UpdateRSProcessedBuffers);
+  _update_rs_scanned_cards = new WorkerDataArray<size_t>(max_gc_threads, "Scanned Cards:");
+  _gc_par_phases[UpdateRS]->link_thread_work_items(_update_rs_scanned_cards, UpdateRSScannedCards);
+  _update_rs_skipped_cards = new WorkerDataArray<size_t>(max_gc_threads, "Skipped Cards:");
+  _gc_par_phases[UpdateRS]->link_thread_work_items(_update_rs_skipped_cards, ScanRSSkippedCards);
 
   _termination_attempts = new WorkerDataArray<size_t>(max_gc_threads, "Termination Attempts:");
   _gc_par_phases[Termination]->link_thread_work_items(_termination_attempts);

--- a/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.hpp	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1GCPhaseTimes.hpp	Wed Aug 09 17:27:42 2017 +0200
@@ -78,9 +78,15 @@
   };
 
   enum GCScanRSWorkItems {
-    ScannedCards,
-    ClaimedCards,
-    SkippedCards
+    ScanRSScannedCards,
+    ScanRSClaimedCards,
+    ScanRSSkippedCards
+  };
+
+  enum GCUpdateRSWorkItems {
+    UpdateRSProcessedBuffers,
+    UpdateRSScannedCards,
+    UpdateRSSkippedCards
   };
 
  private:
@@ -92,6 +98,8 @@
   WorkerDataArray<double>* _gc_par_phases[GCParPhasesSentinel];
 
   WorkerDataArray<size_t>* _update_rs_processed_buffers;
+  WorkerDataArray<size_t>* _update_rs_scanned_cards;
+  WorkerDataArray<size_t>* _update_rs_skipped_cards;
 
   WorkerDataArray<size_t>* _scan_rs_scanned_cards;
   WorkerDataArray<size_t>* _scan_rs_claimed_cards;

--- a/hotspot/src/share/vm/gc/g1/g1RemSet.cpp	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1RemSet.cpp	Wed Aug 09 17:27:42 2017 +0200
@@ -429,9 +429,9 @@
   G1GCPhaseTimes* p = _g1p->phase_times();
 
   p->record_time_secs(G1GCPhaseTimes::ScanRS, worker_i, scan_rs_time_sec);
-  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_scanned(), G1GCPhaseTimes::ScannedCards);
-  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_claimed(), G1GCPhaseTimes::ClaimedCards);
-  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_skipped(), G1GCPhaseTimes::SkippedCards);
+  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_scanned(), G1GCPhaseTimes::ScanRSScannedCards);
+  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_claimed(), G1GCPhaseTimes::ScanRSClaimedCards);
+  p->record_thread_work_item(G1GCPhaseTimes::ScanRS, worker_i, cl.cards_skipped(), G1GCPhaseTimes::ScanRSSkippedCards);
 
   p->record_time_secs(G1GCPhaseTimes::CodeRoots, worker_i, cl.strong_code_root_scan_time_sec());
 }
@@ -440,9 +440,12 @@
 class G1RefineCardClosure: public CardTableEntryClosure {
   G1RemSet* _g1rs;
   G1ScanObjsDuringUpdateRSClosure* _update_rs_cl;
+
+  size_t _cards_scanned;
+  size_t _cards_skipped;
 public:
   G1RefineCardClosure(G1CollectedHeap* g1h, G1ScanObjsDuringUpdateRSClosure* update_rs_cl) :
-    _g1rs(g1h->g1_rem_set()), _update_rs_cl(update_rs_cl)
+    _g1rs(g1h->g1_rem_set()), _update_rs_cl(update_rs_cl), _cards_scanned(0), _cards_skipped(0)
   {}
 
   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
@@ -452,9 +455,18 @@
     // In this case worker_i should be the id of a GC worker thread.
     assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
 
-    _g1rs->refine_card_during_gc(card_ptr, _update_rs_cl);
+    bool card_scanned = _g1rs->refine_card_during_gc(card_ptr, _update_rs_cl);
+
+    if (card_scanned) {
+      _cards_scanned++;
+    } else {
+      _cards_skipped++;
+    }
     return true;
   }
+
+  size_t cards_scanned() const { return _cards_scanned; }
+  size_t cards_skipped() const { return _cards_skipped; }
 };
 
 void G1RemSet::update_rem_set(G1ParScanThreadState* pss, uint worker_i) {
@@ -469,6 +481,10 @@
   }
   // Apply the closure to all remaining log entries.
   _g1->iterate_dirty_card_closure(&refine_card_cl, worker_i);
+
+  G1GCPhaseTimes* p = _g1p->phase_times();
+  p->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, refine_card_cl.cards_scanned(), G1GCPhaseTimes::UpdateRSScannedCards);
+  p->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, refine_card_cl.cards_skipped(), G1GCPhaseTimes::UpdateRSSkippedCards);
 }
 
 void G1RemSet::cleanupHRRS() {
@@ -680,7 +696,7 @@
   }
 }
 
-void G1RemSet::refine_card_during_gc(jbyte* card_ptr,
+bool G1RemSet::refine_card_during_gc(jbyte* card_ptr,
                                      G1ScanObjsDuringUpdateRSClosure* update_rs_cl) {
   assert(_g1->is_gc_active(), "Only call during GC");
 
@@ -689,7 +705,7 @@
   // If the card is no longer dirty, nothing to do. This covers cards that were already
   // scanned as parts of the remembered sets.
   if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
-    return;
+    return false;
   }
 
   // We claim lazily (so races are possible but they're benign), which reduces the
@@ -705,7 +721,7 @@
   HeapWord* scan_limit = _scan_state->scan_top(card_region_idx);
   if (scan_limit <= card_start) {
     // If the card starts above the area in the region containing objects to scan, skip it.
-    return;
+    return false;
   }
 
   // Don't use addr_for(card_ptr + 1) which can ask for
@@ -718,6 +734,7 @@
   update_rs_cl->set_region(card_region);
   bool card_processed = card_region->oops_on_card_seq_iterate_careful<true>(dirty_region, update_rs_cl);
   assert(card_processed, "must be");
+  return true;
 }
 
 void G1RemSet::print_periodic_summary_info(const char* header, uint period_count) {

--- a/hotspot/src/share/vm/gc/g1/g1RemSet.hpp	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1RemSet.hpp	Wed Aug 09 17:27:42 2017 +0200
@@ -128,7 +128,8 @@
 
   // Refine the card corresponding to "card_ptr", applying the given closure to
   // all references found. Must only be called during gc.
-  void refine_card_during_gc(jbyte* card_ptr, G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
+  // Returns whether the card has been scanned.
+  bool refine_card_during_gc(jbyte* card_ptr, G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
 
   // Print accumulated summary info from the start of the VM.
   void print_summary_info();

--- a/hotspot/test/gc/g1/TestGCLogMessages.java	Tue Aug 08 22:58:44 2017 +0200
+++ b/hotspot/test/gc/g1/TestGCLogMessages.java	Wed Aug 09 17:27:42 2017 +0200
@@ -96,6 +96,8 @@
         // Update RS
         new LogMessageWithLevel("Update RS", Level.DEBUG),
         new LogMessageWithLevel("Processed Buffers", Level.DEBUG),
+        new LogMessageWithLevel("Scanned Cards", Level.DEBUG),
+        new LogMessageWithLevel("Skipped Cards", Level.DEBUG),
         new LogMessageWithLevel("Scan HCC", Level.TRACE),
         // Scan RS
         new LogMessageWithLevel("Scan RS", Level.DEBUG),