--- old/src/hotspot/share/gc/g1/g1RegionToSpaceMapper.hpp	2020-01-03 17:56:51.092840116 +0800
+++ new/src/hotspot/share/gc/g1/g1RegionToSpaceMapper.hpp	2020-01-03 17:56:51.094840187 +0800
@@ -97,6 +97,9 @@
                                                    size_t region_granularity,
                                                    size_t byte_translation_factor,
                                                    MemoryType type);
+
+  // If the mapper can commit/uncommit region parallelly
+  virtual bool can_parallelly_commit_and_uncommit() const = 0;
 };
 
 // G1RegionToSpaceMapper implementation where
@@ -120,5 +123,7 @@
 
   virtual void commit_regions(uint start_idx, size_t num_regions = 1, WorkGang* pretouch_workers = NULL);
   virtual void uncommit_regions(uint start_idx, size_t num_regions = 1);
+
+  virtual bool can_parallelly_commit_and_uncommit() const;
 };
 #endif // SHARE_GC_G1_G1REGIONTOSPACEMAPPER_HPP