--- a/src/hotspot/share/gc/g1/g1DefaultPolicy.hpp	Mon Oct 23 11:46:12 2017 +0200
+++ b/src/hotspot/share/gc/g1/g1DefaultPolicy.hpp	Mon Oct 23 11:46:25 2017 +0200
@@ -238,6 +238,9 @@
   uint calc_min_old_cset_length() const;
   uint calc_max_old_cset_length() const;
 
+  // Returns the given amount of reclaimable bytes (that represents
+  // the amount of reclaimable space still to be collected) as a
+  // percentage of the current heap capacity.
   double reclaimable_bytes_perc(size_t reclaimable_bytes) const;
 
   jlong collection_pause_end_millis() { return _collection_pause_end_millis; }