JDK-8297796 GenShen: instrument the remembered set scan

src/hotspot/share/gc/shenandoah/shenandoahScanRemembered.inline.hpp

@@ -835,7 +835,7 @@ void ShenandoahScanRemembered<RememberedSet>::log_worker_card_stats(uint worker_
   assert(ShenandoahEnableCardStats, "Do not call");
 
   HdrSeq* worker_card_stats = card_stats(worker_id);
-  log_info(gc, remset)("Worker %u Card Stats Histo: ", worker_id);
+  log_info(gc, remset)("Worker %u Card Stats: ", worker_id);
   log_card_stats(worker_card_stats);
   // Merge worker stats into the cumulative stats & clear worker stats
   merge_worker_card_stats_cumulative(worker_card_stats, cum_stats);

src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp

@@ -546,7 +546,8 @@
           "Enable statistics collection related to clean & dirty cards")    \
                                                                             \
   notproduct(int, ShenandoahCardStatsLogInterval, 50,                       \
-          "Log cumulative card stats every so many cycles")                 \
+          "Log cumulative card stats every so many remembered set or "      \
+          "update refs scans")                                              \
   // end of GC_SHENANDOAH_FLAGS
 
 #endif // SHARE_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP