src/share/vm/gc/shared/threadLocalAllocBuffer.hpp

*** 42,59 ****
    friend class JVMCIVMStructs;
  private:
    HeapWord* _start;                              // address of TLAB
    HeapWord* _top;                                // address after last allocation
    HeapWord* _pf_top;                             // allocation prefetch watermark
!   HeapWord* _end;                                // allocation end (excluding alignment_reserve)
    size_t    _desired_size;                       // desired size   (including alignment_reserve)
    size_t    _refill_waste_limit;                 // hold onto tlab if free() is larger than this
    size_t    _allocated_before_last_gc;           // total bytes allocated up until the last gc
  
    static size_t   _max_size;                          // maximum size of any TLAB
    static int      _reserve_for_allocation_prefetch;   // Reserve at the end of the TLAB
    static unsigned _target_refills;                    // expected number of refills between GCs
  
    unsigned  _number_of_refills;
    unsigned  _fast_refill_waste;
    unsigned  _slow_refill_waste;
    unsigned  _gc_waste;
--- 42,63 ----
    friend class JVMCIVMStructs;
  private:
    HeapWord* _start;                              // address of TLAB
    HeapWord* _top;                                // address after last allocation
    HeapWord* _pf_top;                             // allocation prefetch watermark
!   HeapWord* _end;                                // allocation end (can be the sampling end point or
!                                                  //                 the actual TLAB end, excluding alignment_reserve)
!   HeapWord* _actual_end;                         // allocation actual_end (actual TLAB end, excluding alignment_reserve)
    size_t    _desired_size;                       // desired size   (including alignment_reserve)
    size_t    _refill_waste_limit;                 // hold onto tlab if free() is larger than this
    size_t    _allocated_before_last_gc;           // total bytes allocated up until the last gc
  
    static size_t   _max_size;                          // maximum size of any TLAB
    static int      _reserve_for_allocation_prefetch;   // Reserve at the end of the TLAB
    static unsigned _target_refills;                    // expected number of refills between GCs
+   size_t _bytes_until_sample;                         // bytes until sample.
+   size_t _extra_space;                                // extra space due to sampling logic.
  
    unsigned  _number_of_refills;
    unsigned  _fast_refill_waste;
    unsigned  _slow_refill_waste;
    unsigned  _gc_waste;
*** 64,77 ****
--- 68,83 ----
    void accumulate_statistics();
    void initialize_statistics();
  
    void set_start(HeapWord* start)                { _start = start; }
    void set_end(HeapWord* end)                    { _end = end; }
+   void set_actual_end(HeapWord* actual_end)      { _actual_end = actual_end; }
    void set_top(HeapWord* top)                    { _top = top; }
    void set_pf_top(HeapWord* pf_top)              { _pf_top = pf_top; }
    void set_desired_size(size_t desired_size)     { _desired_size = desired_size; }
    void set_refill_waste_limit(size_t waste)      { _refill_waste_limit = waste;  }
+   void set_bytes_until_sample(size_t bytes)      { _bytes_until_sample = bytes;  }
  
    size_t initial_refill_waste_limit()            { return desired_size() / TLABRefillWasteFraction; }
  
    static int    target_refills()                 { return _target_refills; }
    size_t initial_desired_size();
*** 113,123 ****
    static size_t max_size_in_bytes()              { return max_size() * BytesPerWord; }
    static void set_max_size(size_t max_size)      { _max_size = max_size; }
  
    HeapWord* start() const                        { return _start; }
    HeapWord* end() const                          { return _end; }
!   HeapWord* hard_end() const                     { return _end + alignment_reserve(); }
    HeapWord* top() const                          { return _top; }
    HeapWord* pf_top() const                       { return _pf_top; }
    size_t desired_size() const                    { return _desired_size; }
    size_t used() const                            { return pointer_delta(top(), start()); }
    size_t used_bytes() const                      { return pointer_delta(top(), start(), 1); }
--- 119,129 ----
    static size_t max_size_in_bytes()              { return max_size() * BytesPerWord; }
    static void set_max_size(size_t max_size)      { _max_size = max_size; }
  
    HeapWord* start() const                        { return _start; }
    HeapWord* end() const                          { return _end; }
!   HeapWord* hard_end() const                     { return _actual_end + alignment_reserve(); }
    HeapWord* top() const                          { return _top; }
    HeapWord* pf_top() const                       { return _pf_top; }
    size_t desired_size() const                    { return _desired_size; }
    size_t used() const                            { return pointer_delta(top(), start()); }
    size_t used_bytes() const                      { return pointer_delta(top(), start(), 1); }
*** 157,174 ****
--- 163,188 ----
    static void accumulate_statistics_before_gc();
  
    // Resize tlabs for all threads
    static void resize_all_tlabs();
  
+   void set_back_actual_end() { _end = _actual_end; }
    void fill(HeapWord* start, HeapWord* top, size_t new_size);
    void initialize();
  
+   void pick_next_sample();
+   void handle_sample(Thread* thread, HeapWord* result, size_t size);
+   size_t bytes_until_sample() { return _bytes_until_sample; }
+   size_t *bytes_until_sample_addr() { return &_bytes_until_sample; }
+   bool should_sample() { return bytes_until_sample() == 0; }
+ 
    static size_t refill_waste_limit_increment()   { return TLABWasteIncrement; }
  
    // Code generation support
    static ByteSize start_offset()                 { return byte_offset_of(ThreadLocalAllocBuffer, _start); }
    static ByteSize end_offset()                   { return byte_offset_of(ThreadLocalAllocBuffer, _end  ); }
+   static ByteSize actual_end_offset()            { return byte_offset_of(ThreadLocalAllocBuffer, _actual_end  ); }
    static ByteSize top_offset()                   { return byte_offset_of(ThreadLocalAllocBuffer, _top  ); }
    static ByteSize pf_top_offset()                { return byte_offset_of(ThreadLocalAllocBuffer, _pf_top  ); }
    static ByteSize size_offset()                  { return byte_offset_of(ThreadLocalAllocBuffer, _desired_size ); }
    static ByteSize refill_waste_limit_offset()    { return byte_offset_of(ThreadLocalAllocBuffer, _refill_waste_limit ); }