src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp

rev 7989 : 8058354: SPECjvm2008-Derby -2.7% performance regression on Solaris-X64 starting with 9-b29
Summary: Allow partial use of large pages for auxiliary data structures in G1.
Reviewed-by: jmasa
rev 7990 : imported patch 8058354-stefank-review
rev 7991 : imported patch 8058354-more-stefank-review
rev 7992 : imported patch 8058354-more-more-stefank-review
rev 7993 : imported patch per-comments

*** 32,51 ****
  
  // Virtual space management helper for a virtual space with an OS page allocation
  // granularity.
  // (De-)Allocation requests are always OS page aligned by passing a page index
  // and multiples of pages.
  // The implementation gives an error when trying to commit or uncommit pages that
  // have already been committed or uncommitted.
  class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
    friend class VMStructs;
   private:
    // Reserved area addresses.
    char* _low_boundary;
    char* _high_boundary;
  
!   // The commit/uncommit granularity in bytes.
    size_t _page_size;
  
    // Bitmap used for verification of commit/uncommit operations.
    BitMap _committed;
  
--- 32,57 ----
  
  // Virtual space management helper for a virtual space with an OS page allocation
  // granularity.
  // (De-)Allocation requests are always OS page aligned by passing a page index
  // and multiples of pages.
+ // For systems that only commits of memory in a given size (always greater than
+ // page size) the base address is required to be aligned to that commit size.
+ // The actual size requested need not be aligned to the commit size, but the size
+ // of the reservation passed may be rounded up to the commit size. Any fragment
+ // (less than the commit size) of the actual size at the tail of the request will
+ // be committed using OS small pages.
  // The implementation gives an error when trying to commit or uncommit pages that
  // have already been committed or uncommitted.
  class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
    friend class VMStructs;
   private:
    // Reserved area addresses.
    char* _low_boundary;
    char* _high_boundary;
  
!   // The preferred page size used for commit/uncommit in bytes.
    size_t _page_size;
  
    // Bitmap used for verification of commit/uncommit operations.
    BitMap _committed;
  
*** 60,93 ****
    bool _special;
  
    // Indicates whether the committed space should be executable.
    bool _executable;
  
    // Returns the index of the page which contains the given address.
    uintptr_t  addr_to_page_index(char* addr) const;
    // Returns the address of the given page index.
!   char*  page_start(uintptr_t index);
!   // Returns the byte size of the given number of pages.
!   size_t byte_size_for_pages(size_t num);
  
    // Returns true if the entire area is backed by committed memory.
!   bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
    // Returns true if the entire area is not backed by committed memory.
!   bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  
   public:
  
    // Commit the given area of pages starting at start being size_in_pages large.
    // Returns true if the given area is zero filled upon completion.
!   bool commit(uintptr_t start, size_t size_in_pages);
  
    // Uncommit the given area of pages starting at start being size_in_pages large.
!   void uncommit(uintptr_t start, size_t size_in_pages);
  
!   // Initialization
!   G1PageBasedVirtualSpace();
!   bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
  
    // Destruction
    ~G1PageBasedVirtualSpace();
  
    // Amount of reserved memory.
--- 66,124 ----
    bool _special;
  
    // Indicates whether the committed space should be executable.
    bool _executable;
  
+   // Commit the given memory range by using _page_size pages as much as possible
+   // and the remainder with small sized pages. The start address must be _page_size
+   // aligned.
+   void commit_internal(size_t start_page, size_t end_page);
+   // Commit num_pages full pages of _page_size size starting from start. All argument
+   // checking has been performed.
+   void commit_full_pages(size_t start_page, size_t end_page);
+   // Commit the tail area.
+   void commit_tail();
+ 
+   // Uncommit the given memory range.
+   void uncommit_internal(size_t start_page, size_t end_page);
+ 
+   // Pretouch the given memory range.
+   void pretouch_internal(size_t start_page, size_t end_page);
+ 
    // Returns the index of the page which contains the given address.
    uintptr_t  addr_to_page_index(char* addr) const;
    // Returns the address of the given page index.
!   char*  page_start(size_t index);
! 
!   // Is the given page index the last page?
!   bool is_last_page(size_t index) { return index == (_committed.size() - 1); }
!   // Is the given page index the first after last page?
!   bool is_after_last_page(size_t index);
!   // Is the last page only partially covered by this space?
!   bool is_last_page_partial() { return !is_ptr_aligned(_high_boundary, _page_size); }
!   // Returns the end address of the given page bounded by the reserved space.
!   char* bounded_end_addr(size_t end_page);
   
    // Returns true if the entire area is backed by committed memory.
!   bool is_area_committed(size_t start, size_t size_in_pages) const;
    // Returns true if the entire area is not backed by committed memory.
!   bool is_area_uncommitted(size_t start, size_t size_in_pages) const;
  
+   void initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size);
   public:
  
    // Commit the given area of pages starting at start being size_in_pages large.
    // Returns true if the given area is zero filled upon completion.
!   bool commit(size_t start, size_t size_in_pages);
  
    // Uncommit the given area of pages starting at start being size_in_pages large.
!   void uncommit(size_t start, size_t size_in_pages);
  
!   // Initialize the given reserved space with the given base address and the size
!   // actually used.
!   // Prefer to commit in page_size chunks.
!   G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size);
  
    // Destruction
    ~G1PageBasedVirtualSpace();
  
    // Amount of reserved memory.