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src/hotspot/share/memory/heap.hpp

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rev 54914 : 8223444: Improve CodeHeap Free Space Management
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  34 
  35 class HeapBlock {
  36   friend class VMStructs;
  37 
  38  public:
  39   struct Header {
  40     size_t  _length;                             // the length in segments
  41     bool    _used;                               // Used bit
  42   };
  43 
  44  protected:
  45   union {
  46     Header _header;
  47     int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
  48                         // pad to 0 mod 8
  49   };
  50 
  51  public:
  52   // Initialization
  53   void initialize(size_t length)                 { _header._length = length; set_used(); }


  54 
  55   // Accessors
  56   void* allocated_space() const                  { return (void*)(this + 1); }
  57   size_t length() const                          { return _header._length; }
  58 
  59   // Used/free
  60   void set_used()                                { _header._used = true; }
  61   void set_free()                                { _header._used = false; }
  62   bool free()                                    { return !_header._used; }
  63 };
  64 
  65 class FreeBlock: public HeapBlock {
  66   friend class VMStructs;
  67  protected:
  68   FreeBlock* _link;
  69 
  70  public:
  71   // Initialization
  72   void initialize(size_t length)             { HeapBlock::initialize(length); _link= NULL; }
  73 
  74   // Merging
  75   void set_length(size_t l)                  { _header._length = l; }
  76 
  77   // Accessors
  78   FreeBlock* link() const                    { return _link; }
  79   void set_link(FreeBlock* link)             { _link = link; }
  80 };
  81 
  82 class CodeHeap : public CHeapObj<mtCode> {
  83   friend class VMStructs;
  84  protected:
  85   VirtualSpace _memory;                          // the memory holding the blocks
  86   VirtualSpace _segmap;                          // the memory holding the segment map
  87 
  88   size_t       _number_of_committed_segments;
  89   size_t       _number_of_reserved_segments;
  90   size_t       _segment_size;
  91   int          _log2_segment_size;
  92 
  93   size_t       _next_segment;
  94 
  95   FreeBlock*   _freelist;
  96   size_t       _freelist_segments;               // No. of segments in freelist


  98   size_t       _max_allocated_capacity;          // Peak capacity that was allocated during lifetime of the heap
  99 
 100   const char*  _name;                            // Name of the CodeHeap
 101   const int    _code_blob_type;                  // CodeBlobType it contains
 102   int          _blob_count;                      // Number of CodeBlobs
 103   int          _nmethod_count;                   // Number of nmethods
 104   int          _adapter_count;                   // Number of adapters
 105   int          _full_count;                      // Number of times the code heap was full
 106 
 107 
 108   enum { free_sentinel = 0xFF };
 109 
 110   // Helper functions
 111   size_t   size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
 112   size_t   segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
 113 
 114   size_t   segment_for(void* p) const            { return ((char*)p - _memory.low()) >> _log2_segment_size; }
 115   bool     is_segment_unused(int val) const      { return val == free_sentinel; }
 116   HeapBlock* block_at(size_t i) const            { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }
 117 

 118   void  mark_segmap_as_free(size_t beg, size_t end);
 119   void  mark_segmap_as_used(size_t beg, size_t end);



 120 
 121   // Freelist management helpers
 122   FreeBlock* following_block(FreeBlock* b);
 123   void insert_after(FreeBlock* a, FreeBlock* b);
 124   bool merge_right (FreeBlock* a);
 125 
 126   // Toplevel freelist management
 127   void add_to_freelist(HeapBlock* b);
 128   FreeBlock* search_freelist(size_t length);
 129 
 130   // Iteration helpers
 131   void*      next_used(HeapBlock* b) const;
 132   HeapBlock* block_start(void* p) const;
 133 
 134   // to perform additional actions on creation of executable code
 135   void on_code_mapping(char* base, size_t size);
 136   void clear();                                 // clears all heap contents
 137 
 138  public:
 139   CodeHeap(const char* name, const int code_blob_type);
 140 
 141   // Heap extents
 142   bool  reserve(ReservedSpace rs, size_t committed_size, size_t segment_size);
 143   bool  expand_by(size_t size);                  // expands committed memory by size
 144 
 145   // Memory allocation
 146   void* allocate (size_t size); // Allocate 'size' bytes in the code cache or return NULL
 147   void  deallocate(void* p);    // Deallocate memory
 148   // Free the tail of segments allocated by the last call to 'allocate()' which exceed 'used_size'.
 149   // ATTENTION: this is only safe to use if there was no other call to 'allocate()' after
 150   //            'p' was allocated. Only intended for freeing memory which would be otherwise
 151   //            wasted after the interpreter generation because we don't know the interpreter size
 152   //            beforehand and we also can't easily relocate the interpreter to a new location.
 153   void  deallocate_tail(void* p, size_t used_size);
 154 
 155   // Attributes
 156   char* low_boundary() const                     { return _memory.low_boundary(); }


 163     // Only the code they are pointing to is located in the AOTCodeHeap. All other CodeBlobs are allocated
 164     // directly in their corresponding CodeHeap with their code appended to the actual C++ object.
 165     // So all CodeBlobs except AOTCompiledMethod are continuous in memory with their data and code while
 166     // AOTCompiledMethod and their code/data is distributed in the C-Heap. This means we can use the
 167     // address of a CodeBlob object in order to locate it in its heap while we have to use the address
 168     // of the actual code an AOTCompiledMethod object is pointing to in order to locate it.
 169     // Notice that for an ordinary CodeBlob with code size zero, code_begin() may point beyond the object!
 170     const void* start = AOT_ONLY( (code_blob_type() == CodeBlobType::AOT) ? blob->code_begin() : ) (void*)blob;
 171     return contains(start);
 172   }
 173 
 174   virtual void* find_start(void* p)     const;   // returns the block containing p or NULL
 175   virtual CodeBlob* find_blob_unsafe(void* start) const;
 176   size_t alignment_unit()       const;           // alignment of any block
 177   size_t alignment_offset()     const;           // offset of first byte of any block, within the enclosing alignment unit
 178   static size_t header_size();                   // returns the header size for each heap block
 179 
 180   size_t segment_size()         const { return _segment_size; }  // for CodeHeapState
 181   HeapBlock* first_block() const;                                // for CodeHeapState
 182   HeapBlock* next_block(HeapBlock* b) const;                     // for CodeHeapState

 183 
 184   FreeBlock* freelist()         const { return _freelist; }      // for CodeHeapState
 185 
 186   size_t allocated_in_freelist() const           { return _freelist_segments * CodeCacheSegmentSize; }
 187   int    freelist_length()       const           { return _freelist_length; } // number of elements in the freelist
 188 
 189   // returns the first block or NULL
 190   virtual void* first() const                    { return next_used(first_block()); }
 191   // returns the next block given a block p or NULL
 192   virtual void* next(void* p) const              { return next_used(next_block(block_start(p))); }
 193 
 194   // Statistics
 195   size_t capacity() const;
 196   size_t max_capacity() const;
 197   int    allocated_segments() const;
 198   size_t allocated_capacity() const;
 199   size_t max_allocated_capacity() const          { return _max_allocated_capacity; }
 200   size_t unallocated_capacity() const            { return max_capacity() - allocated_capacity(); }
 201 
 202   // Returns true if the CodeHeap contains CodeBlobs of the given type




  34 
  35 class HeapBlock {
  36   friend class VMStructs;
  37 
  38  public:
  39   struct Header {
  40     size_t  _length;                             // the length in segments
  41     bool    _used;                               // Used bit
  42   };
  43 
  44  protected:
  45   union {
  46     Header _header;
  47     int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
  48                         // pad to 0 mod 8
  49   };
  50 
  51  public:
  52   // Initialization
  53   void initialize(size_t length)                 { _header._length = length; set_used(); }
  54   // Merging/splitting
  55   void set_length(size_t length)                 { _header._length = length; }
  56 
  57   // Accessors
  58   void* allocated_space() const                  { return (void*)(this + 1); }
  59   size_t length() const                          { return _header._length; }
  60 
  61   // Used/free
  62   void set_used()                                { _header._used = true; }
  63   void set_free()                                { _header._used = false; }
  64   bool free()                                    { return !_header._used; }
  65 };
  66 
  67 class FreeBlock: public HeapBlock {
  68   friend class VMStructs;
  69  protected:
  70   FreeBlock* _link;
  71 
  72  public:
  73   // Initialization
  74   void initialize(size_t length)             { HeapBlock::initialize(length); _link= NULL; }
  75 



  76   // Accessors
  77   FreeBlock* link() const                    { return _link; }
  78   void set_link(FreeBlock* link)             { _link = link; }
  79 };
  80 
  81 class CodeHeap : public CHeapObj<mtCode> {
  82   friend class VMStructs;
  83  protected:
  84   VirtualSpace _memory;                          // the memory holding the blocks
  85   VirtualSpace _segmap;                          // the memory holding the segment map
  86 
  87   size_t       _number_of_committed_segments;
  88   size_t       _number_of_reserved_segments;
  89   size_t       _segment_size;
  90   int          _log2_segment_size;
  91 
  92   size_t       _next_segment;
  93 
  94   FreeBlock*   _freelist;
  95   size_t       _freelist_segments;               // No. of segments in freelist


  97   size_t       _max_allocated_capacity;          // Peak capacity that was allocated during lifetime of the heap
  98 
  99   const char*  _name;                            // Name of the CodeHeap
 100   const int    _code_blob_type;                  // CodeBlobType it contains
 101   int          _blob_count;                      // Number of CodeBlobs
 102   int          _nmethod_count;                   // Number of nmethods
 103   int          _adapter_count;                   // Number of adapters
 104   int          _full_count;                      // Number of times the code heap was full
 105 
 106 
 107   enum { free_sentinel = 0xFF };
 108 
 109   // Helper functions
 110   size_t   size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
 111   size_t   segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
 112 
 113   size_t   segment_for(void* p) const            { return ((char*)p - _memory.low()) >> _log2_segment_size; }
 114   bool     is_segment_unused(int val) const      { return val == free_sentinel; }
 115   HeapBlock* block_at(size_t i) const            { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }
 116 
 117   // These methods take segment map indices as range boundaries
 118   void mark_segmap_as_free(size_t beg, size_t end);
 119   void mark_segmap_as_used(size_t beg, size_t end);
 120   void invalidate(size_t beg, size_t end, size_t header_bytes);
 121   void clear(size_t beg, size_t end);
 122   void clear();                                 // clears all heap contents
 123 
 124   // Freelist management helpers
 125   FreeBlock* following_block(FreeBlock* b);
 126   void insert_after(FreeBlock* a, FreeBlock* b);
 127   bool merge_right (FreeBlock* a);
 128 
 129   // Toplevel freelist management
 130   void add_to_freelist(HeapBlock* b);
 131   HeapBlock* search_freelist(size_t length);
 132 
 133   // Iteration helpers
 134   void*      next_used(HeapBlock* b) const;
 135   HeapBlock* block_start(void* p) const;
 136 
 137   // to perform additional actions on creation of executable code
 138   void on_code_mapping(char* base, size_t size);

 139 
 140  public:
 141   CodeHeap(const char* name, const int code_blob_type);
 142 
 143   // Heap extents
 144   bool  reserve(ReservedSpace rs, size_t committed_size, size_t segment_size);
 145   bool  expand_by(size_t size);                  // expands committed memory by size
 146 
 147   // Memory allocation
 148   void* allocate (size_t size); // Allocate 'size' bytes in the code cache or return NULL
 149   void  deallocate(void* p);    // Deallocate memory
 150   // Free the tail of segments allocated by the last call to 'allocate()' which exceed 'used_size'.
 151   // ATTENTION: this is only safe to use if there was no other call to 'allocate()' after
 152   //            'p' was allocated. Only intended for freeing memory which would be otherwise
 153   //            wasted after the interpreter generation because we don't know the interpreter size
 154   //            beforehand and we also can't easily relocate the interpreter to a new location.
 155   void  deallocate_tail(void* p, size_t used_size);
 156 
 157   // Attributes
 158   char* low_boundary() const                     { return _memory.low_boundary(); }


 165     // Only the code they are pointing to is located in the AOTCodeHeap. All other CodeBlobs are allocated
 166     // directly in their corresponding CodeHeap with their code appended to the actual C++ object.
 167     // So all CodeBlobs except AOTCompiledMethod are continuous in memory with their data and code while
 168     // AOTCompiledMethod and their code/data is distributed in the C-Heap. This means we can use the
 169     // address of a CodeBlob object in order to locate it in its heap while we have to use the address
 170     // of the actual code an AOTCompiledMethod object is pointing to in order to locate it.
 171     // Notice that for an ordinary CodeBlob with code size zero, code_begin() may point beyond the object!
 172     const void* start = AOT_ONLY( (code_blob_type() == CodeBlobType::AOT) ? blob->code_begin() : ) (void*)blob;
 173     return contains(start);
 174   }
 175 
 176   virtual void* find_start(void* p)     const;   // returns the block containing p or NULL
 177   virtual CodeBlob* find_blob_unsafe(void* start) const;
 178   size_t alignment_unit()       const;           // alignment of any block
 179   size_t alignment_offset()     const;           // offset of first byte of any block, within the enclosing alignment unit
 180   static size_t header_size();                   // returns the header size for each heap block
 181 
 182   size_t segment_size()         const { return _segment_size; }  // for CodeHeapState
 183   HeapBlock* first_block() const;                                // for CodeHeapState
 184   HeapBlock* next_block(HeapBlock* b) const;                     // for CodeHeapState
 185   HeapBlock* split_block(HeapBlock* b, size_t split_seg);        // split one block into two
 186 
 187   FreeBlock* freelist()         const { return _freelist; }      // for CodeHeapState
 188 
 189   size_t allocated_in_freelist() const           { return _freelist_segments * CodeCacheSegmentSize; }
 190   int    freelist_length()       const           { return _freelist_length; } // number of elements in the freelist
 191 
 192   // returns the first block or NULL
 193   virtual void* first() const                    { return next_used(first_block()); }
 194   // returns the next block given a block p or NULL
 195   virtual void* next(void* p) const              { return next_used(next_block(block_start(p))); }
 196 
 197   // Statistics
 198   size_t capacity() const;
 199   size_t max_capacity() const;
 200   int    allocated_segments() const;
 201   size_t allocated_capacity() const;
 202   size_t max_allocated_capacity() const          { return _max_allocated_capacity; }
 203   size_t unallocated_capacity() const            { return max_capacity() - allocated_capacity(); }
 204 
 205   // Returns true if the CodeHeap contains CodeBlobs of the given type


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