src/share/vm/gc_implementation/shared/parGCAllocBuffer.hpp

@@ -43,10 +43,11 @@
   HeapWord* _end;           // Last allocatable address + 1
   HeapWord* _hard_end;      // _end + AlignmentReserve
   // In support of ergonomic sizing of PLAB's
   size_t    _allocated;     // in HeapWord units
   size_t    _wasted;        // in HeapWord units
+  size_t    _undo_wasted;
   char      tail[32];
   static size_t AlignmentReserve;
 
   // Force future allocations to fail and queries for contains()
   // to return false. Returns the amount of unused space in this PLAB.

@@ -96,14 +97,21 @@
     assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
     assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
     _top = obj;
   }
 
+  void add_undo_waste(size_t word_sz) {
+    _undo_wasted += word_sz;
+  }
+
   // The total (word) size of the buffer, including both allocated and
   // unallocated space.
   size_t word_sz() { return _word_sz; }
 
+  size_t wasted() { return _wasted; }
+  size_t undo_wasted() { return _undo_wasted; }
+
   // Should only be done if we are about to reset with a new buffer of the
   // given size.
   void set_word_size(size_t new_word_sz) {
     assert(new_word_sz > AlignmentReserve, "Too small");
     _word_sz = new_word_sz;