--- old/src/hotspot/share/gc/g1/g1Policy.cpp	2019-11-20 14:56:37.077025344 +0100
+++ new/src/hotspot/share/gc/g1/g1Policy.cpp	2019-11-20 14:56:36.734014727 +0100
@@ -722,7 +722,11 @@
                                       p->sum_thread_work_items(G1GCPhaseTimes::OptMergeRS, G1GCPhaseTimes::MergeRSDirtyCards) +
                                       total_log_buffer_cards;
 
-    if (total_cards_merged > 10) {
+    // The threshold for the number of cards in a given sampling which we consider
+    // large enough so that the impact from setup and other costs is negligible.
+    size_t const CardsNumSamplingThreshold = 10;
+    
+    if (total_cards_merged > CardsNumSamplingThreshold) {
       double avg_time_merge_cards = average_time_ms(G1GCPhaseTimes::MergeER) +
                                     average_time_ms(G1GCPhaseTimes::MergeRS) +
                                     average_time_ms(G1GCPhaseTimes::MergeHCC) +
@@ -735,7 +739,7 @@
     size_t const total_cards_scanned = p->sum_thread_work_items(G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ScanHRScannedCards) +
                                        p->sum_thread_work_items(G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::ScanHRScannedCards);
 
-    if (total_cards_scanned > 10) {
+    if (total_cards_scanned > CardsNumSamplingThreshold) {
       double avg_time_dirty_card_scan = average_time_ms(G1GCPhaseTimes::ScanHR) +
                                         average_time_ms(G1GCPhaseTimes::OptScanHR);