--- old/src/share/vm/gc/g1/g1RemSet.cpp	2017-07-03 15:54:22.937018578 +0200
+++ new/src/share/vm/gc/g1/g1RemSet.cpp	2017-07-03 15:54:22.806014542 +0200
@@ -724,7 +724,7 @@
       sdcq->enqueue(card_ptr);
     }
   } else {
-    _num_conc_refined_cards++;
+    _num_conc_refined_cards++; // Unsynchronized update, only used for logging.
   }
 }
 
--- old/src/share/vm/gc/g1/g1RemSet.hpp	2017-07-03 15:54:23.565037930 +0200
+++ new/src/share/vm/gc/g1/g1RemSet.hpp	2017-07-03 15:54:23.434033893 +0200
@@ -76,7 +76,7 @@
   void update_rem_set(DirtyCardQueue* into_cset_dcq, G1ParScanThreadState* pss, uint worker_i);
 
   G1CollectedHeap* _g1;
-  size_t _num_conc_refined_cards;
+  size_t _num_conc_refined_cards; // Number of cards refined concurrently to the mutator.
 
   CardTableModRefBS*     _ct_bs;
   G1Policy*              _g1p;
--- old/src/share/vm/gc/g1/g1RemSetSummary.cpp	2017-07-03 15:54:24.206057682 +0200
+++ new/src/share/vm/gc/g1/g1RemSetSummary.cpp	2017-07-03 15:54:24.074053614 +0200
@@ -52,7 +52,7 @@
 };
 
 void G1RemSetSummary::update() {
-  _num_refined_cards = remset()->num_conc_refined_cards();
+  _num_conc_refined_cards = remset()->num_conc_refined_cards();
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   _num_processed_buf_mutator = dcqs.processed_buffers_mut();
   _num_processed_buf_rs_threads = dcqs.processed_buffers_rs_thread();
@@ -93,7 +93,7 @@
 
 G1RemSetSummary::G1RemSetSummary() :
   _remset(NULL),
-  _num_refined_cards(0),
+  _num_conc_refined_cards(0),
   _num_processed_buf_mutator(0),
   _num_processed_buf_rs_threads(0),
   _num_coarsenings(0),
@@ -113,7 +113,7 @@
   assert(remset() == other->remset(), "just checking");
   assert(_num_vtimes == other->_num_vtimes, "just checking");
 
-  _num_refined_cards = other->num_refined_cards();
+  _num_conc_refined_cards = other->num_conc_refined_cards();
 
   _num_processed_buf_mutator = other->num_processed_buf_mutator();
   _num_processed_buf_rs_threads = other->num_processed_buf_rs_threads();
@@ -130,7 +130,7 @@
   assert(remset() == other->remset(), "just checking");
   assert(_num_vtimes == other->_num_vtimes, "just checking");
 
-  _num_refined_cards = other->num_refined_cards() - _num_refined_cards;
+  _num_conc_refined_cards = other->num_conc_refined_cards() - _num_conc_refined_cards;
 
   _num_processed_buf_mutator = other->num_processed_buf_mutator() - _num_processed_buf_mutator;
   _num_processed_buf_rs_threads = other->num_processed_buf_rs_threads() - _num_processed_buf_rs_threads;
@@ -352,7 +352,7 @@
 
 void G1RemSetSummary::print_on(outputStream* out) {
   out->print_cr(" Recent concurrent refinement statistics");
-  out->print_cr("  Processed " SIZE_FORMAT " cards", num_refined_cards());
+  out->print_cr("  Processed " SIZE_FORMAT " cards concurrently", num_conc_refined_cards());
   out->print_cr("  Of " SIZE_FORMAT " completed buffers:", num_processed_buf_total());
   out->print_cr("     " SIZE_FORMAT_W(8) " (%5.1f%%) by concurrent RS threads.",
                 num_processed_buf_total(),
--- old/src/share/vm/gc/g1/g1RemSetSummary.hpp	2017-07-03 15:54:24.839077187 +0200
+++ new/src/share/vm/gc/g1/g1RemSetSummary.hpp	2017-07-03 15:54:24.709073182 +0200
@@ -42,7 +42,7 @@
     return _remset;
   }
 
-  size_t _num_refined_cards;
+  size_t _num_conc_refined_cards;
   size_t _num_processed_buf_mutator;
   size_t _num_processed_buf_rs_threads;
 
@@ -82,8 +82,8 @@
     return _sampling_thread_vtime;
   }
 
-  size_t num_refined_cards() const {
-    return _num_refined_cards;
+  size_t num_conc_refined_cards() const {
+    return _num_conc_refined_cards;
   }
 
   size_t num_processed_buf_mutator() const {