--- old/src/hotspot/share/gc/g1/g1Analytics.cpp	2019-11-20 14:56:34.536946729 +0100
+++ new/src/hotspot/share/gc/g1/g1Analytics.cpp	2019-11-20 14:56:34.202936391 +0100
@@ -244,7 +244,7 @@
 }
 
 size_t G1Analytics::predict_scan_card_num(size_t rs_length, bool for_young_gc) const {
-  if (for_young_gc || _mixed_card_merge_to_scan_ratio_seq->num() < 3) {
+  if (for_young_gc || !enough_samples_available(_mixed_card_merge_to_scan_ratio_seq)) {
     return (size_t) (rs_length * predict_young_card_merge_to_scan_ratio());
   } else {
     return (size_t) (rs_length * get_new_prediction(_mixed_card_merge_to_scan_ratio_seq));
@@ -252,7 +252,7 @@
 }
 
 double G1Analytics::predict_card_merge_time_ms(size_t card_num, bool for_young_gc) const {
-  if (for_young_gc || _mixed_cost_per_card_merge_ms_seq->num() < 3) {
+  if (for_young_gc || !enough_samples_available(_mixed_cost_per_card_merge_ms_seq->num())) {
     return card_num * get_new_prediction(_young_cost_per_card_merge_ms_seq);
   } else {
     return card_num * get_new_prediction(_mixed_cost_per_card_merge_ms_seq);
@@ -260,7 +260,7 @@
 }
 
 double G1Analytics::predict_card_scan_time_ms(size_t card_num, bool for_young_gc) const {
-  if (for_young_gc || _mixed_cost_per_card_scan_ms_seq->num() < 3) {
+  if (for_young_gc || !enough_samples_available(_mixed_cost_per_card_scan_ms_seq->num())) {
     return card_num * get_new_prediction(_young_cost_per_card_scan_ms_seq);
   } else {
     return card_num * get_new_prediction(_mixed_cost_per_card_scan_ms_seq);
@@ -268,7 +268,7 @@
 }
 
 double G1Analytics::predict_object_copy_time_ms_during_cm(size_t bytes_to_copy) const {
-  if (_cost_per_byte_ms_during_cm_seq->num() < 3) {
+  if (!enough_samples_available(_cost_per_byte_ms_during_cm_seq)) {
     return (1.1 * bytes_to_copy) * get_new_prediction(_copy_cost_per_byte_ms_seq);
   } else {
     return bytes_to_copy * get_new_prediction(_cost_per_byte_ms_during_cm_seq);