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

rev 7746 : 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:
rev 7747 : [mq]: 8058354-jon-fixes

*** 32,52 ****
  
  // 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;
  
    // Bitmap used to keep track of which pages are dirty or not for _special
--- 32,58 ----
  
  // 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 commit/uncommit granularity in bytes.
!   size_t _commit_size;
  
    // Bitmap used for verification of commit/uncommit operations.
    BitMap _committed;
  
    // Bitmap used to keep track of which pages are dirty or not for _special
*** 60,75 ****
    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;
--- 66,89 ----
    bool _special;
  
    // Indicates whether the committed space should be executable.
    bool _executable;
  
+   // Commit the given memory range by using _commit_size pages as much as possible
+   // and the remainder with small sized pages. The start address must be _commit_size
+   // aligned.
+   void commit_internal(char* start, char* end);
+   // Uncommit the given memory range.
+   void uncommit_internal(char* start, char* end);
+ 
    // 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 address of the end of the page given the page index ranging
!   // from 0..size_in_pages-2. For the last page, return _high_boundary.
!   char*  page_end(uintptr_t index);
  
    // 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;
*** 83,93 ****
    // 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.
--- 97,109 ----
    // 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();
!   // Initialize the given reserved space with the given base address and actual size.
!   // Prefer to commit in commit_size chunks.
!   bool initialize_with_granularity(ReservedSpace rs, size_t actual_size, size_t commit_size);
  
    // Destruction
    ~G1PageBasedVirtualSpace();
  
    // Amount of reserved memory.