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

*** 43,52 ****
--- 43,53 ----
    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.
*** 60,69 ****
--- 61,83 ----
  
    // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
    // the amount of remaining space.
    size_t retire_internal();
    
+   void add_undo_waste(HeapWord* obj, size_t word_sz) {
+     CollectedHeap::fill_with_object(obj, word_sz);
+     _undo_wasted += word_sz;
+   }
+   
+   // Undo the last allocation in the buffer, which is required to be of the
+   // "obj" of the given "word_sz".
+   void undo_last_allocation(HeapWord* obj, size_t word_sz) {
+     assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
+     assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
+     _top = obj;
+   }
+ 
  public:
    // Initializes the buffer to be empty, but with the given "word_sz".
    // Must get initialized with "set_buf" for an allocation to succeed.
    ParGCAllocBuffer(size_t word_sz);
    virtual ~ParGCAllocBuffer() {}
*** 88,109 ****
    }
  
    // Allocate the object aligned to "alignment_in_bytes".
    HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
  
!   // Undo the last allocation in the buffer, which is required to be of the
    // "obj" of the given "word_sz".
    void undo_allocation(HeapWord* obj, size_t word_sz) {
!     assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
!     assert(pointer_delta(_top, obj)     == word_sz, "Bad undo");
!     _top = obj;
    }
  
    // The total (word) size of the buffer, including both allocated and
    // unallocated space.
    size_t word_sz() { return _word_sz; }
  
    // 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;
--- 102,131 ----
    }
  
    // Allocate the object aligned to "alignment_in_bytes".
    HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
  
!   // Undo any allocation in the buffer, which is required to be of the
    // "obj" of the given "word_sz".
    void undo_allocation(HeapWord* obj, size_t word_sz) {
!     // Is the alloc in the current alloc buffer?
!     if (contains(obj)) {
!       assert(contains(obj + word_sz - 1),
!              "should contain whole object");
!       undo_last_allocation(obj, word_sz);
!     } else {
!       add_undo_waste(obj,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;
*** 144,167 ****
--- 166,192 ----
  
  // PLAB book-keeping.
  class PLABStats VALUE_OBJ_CLASS_SPEC {
    size_t _allocated;      // Total allocated
    size_t _wasted;         // of which wasted (internal fragmentation)
+   size_t _undo_wasted;    // of which wasted on undo (is not used for calculation of PLAB size)
    size_t _unused;         // Unused in last buffer
    size_t _desired_plab_sz;// Output of filter (below), suitably trimmed and quantized
    AdaptiveWeightedAverage
           _filter;         // Integrator with decay
  
    void reset() {
      _allocated   = 0;
      _wasted      = 0;
+     _undo_wasted = 0;
      _unused      = 0;
    }
   public:
    PLABStats(size_t desired_plab_sz_, unsigned wt) :
      _allocated(0),
      _wasted(0),
+     _undo_wasted(0),
      _unused(0),
      _desired_plab_sz(desired_plab_sz_),
      _filter(wt)
    { }
  
*** 190,197 ****
--- 215,226 ----
    }
  
    void add_wasted(size_t v) {
      Atomic::add_ptr(v, &_wasted);
    }
+   
+   void add_undo_wasted(size_t v) {
+     Atomic::add_ptr(v, &_undo_wasted);
+   }
  };
  
  #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP