--- old/src/hotspot/share/gc/g1/g1HeapSizingPolicy.hpp	2020-02-17 17:22:56.808265615 +0800
+++ new/src/hotspot/share/gc/g1/g1HeapSizingPolicy.hpp	2020-02-17 17:22:56.810265687 +0800
@@ -45,6 +45,9 @@
   double _ratio_over_threshold_sum;
   uint _pauses_since_start;
 
+  // Mininum heap capacity after last concurrent mark
+  size_t _minimum_desired_bytes_after_last_cm;
+
 
 protected:
   G1HeapSizingPolicy(const G1CollectedHeap* g1h, const G1Analytics* analytics);
@@ -52,8 +55,12 @@
 
   // If an expansion would be appropriate, because recent GC overhead had
   // exceeded the desired limit, return an amount to expand by.
-  virtual size_t expansion_amount();
+  virtual size_t expansion_amount_after_young_collection();
+  virtual size_t expansion_amount_after_concurrent_mark();
+  virtual size_t shrink_amount_after_mixed_collections();
 
+  // Calculate the target capacity based on used bytes and free ratio
+  virtual size_t target_heap_capacity(size_t used_bytes,  uintx free_ratio);
   // Clear ratio tracking data used by expansion_amount().
   void clear_ratio_check_data();