--- old/src/hotspot/share/gc/g1/g1Analytics.cpp	2019-12-04 15:38:55.882621296 +0100
+++ new/src/hotspot/share/gc/g1/g1Analytics.cpp	2019-12-04 15:38:55.666619647 +0100
@@ -94,6 +94,7 @@
     _rs_length_seq(new TruncatedSeq(TruncatedSeqLength)),
     _cost_per_byte_ms_during_cm_seq(new TruncatedSeq(TruncatedSeqLength)),
     _recent_prev_end_times_for_all_gcs_sec(new TruncatedSeq(NumPrevPausesForHeuristics)),
+    _survivor_ratio(new TruncatedSeq(TruncatedSeqLength)),
     _recent_avg_pause_time_ratio(0.0),
     _last_pause_time_ratio(0.0) {
 
@@ -119,6 +120,8 @@
   // start conservatively (around 50ms is about right)
   _concurrent_mark_remark_times_ms->add(0.05);
   _concurrent_mark_cleanup_times_ms->add(0.20);
+
+  _survivor_ratio->add(0.5);
 }
 
 bool G1Analytics::enough_samples_available(TruncatedSeq const* seq) const {
@@ -228,6 +231,10 @@
   _rs_length_seq->add(rs_length);
 }
 
+void G1Analytics::report_survivor_ratio(double ratio) {
+  _survivor_ratio->add(ratio);
+}
+
 double G1Analytics::predict_alloc_rate_ms() const {
   return predict_zero_bounded(_alloc_rate_ms_seq);
 }
@@ -284,6 +291,10 @@
   }
 }
 
+double G1Analytics::predict_survivor_ratio() const {
+  return predict_in_unit_interval(_survivor_ratio);
+}
+
 double G1Analytics::predict_constant_other_time_ms() const {
   return predict_zero_bounded(_constant_other_time_ms_seq);
 }