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

   1 /*
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   6  * under the terms of the GNU General Public License version 2 only, as
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "memory/memRegion.hpp"
  30 #include "runtime/virtualspace.hpp"
  31 #include "utilities/bitMap.hpp"
  32 
  33 // Virtual space management helper for a virtual space with an OS page allocation
  34 // granularity.
  35 // (De-)Allocation requests are always OS page aligned by passing a page index
  36 // and multiples of pages.
  37 // For systems that only commits of memory in a given size (always greater than
  38 // page size) the base address is required to be aligned to that commit size.
  39 // The actual size requested need not be aligned to the commit size, but the size
  40 // of the reservation passed may be rounded up to the commit size. Any fragment
  41 // (less than the commit size) of the actual size at the tail of the request will
  42 // be committed using OS small pages.
  43 // The implementation gives an error when trying to commit or uncommit pages that
  44 // have already been committed or uncommitted.
  45 class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
  46   friend class VMStructs;
  47  private:
  48   // Reserved area addresses.
  49   char* _low_boundary;
  50   char* _high_boundary;
  51 
  52   // The preferred commit/uncommit granularity in bytes.
  53   size_t _commit_size;
  54 
  55   // Bitmap used for verification of commit/uncommit operations.
  56   BitMap _committed;
  57 
  58   // Bitmap used to keep track of which pages are dirty or not for _special
  59   // spaces. This is needed because for those spaces the underlying memory
  60   // will only be zero filled the first time it is committed. Calls to commit
  61   // will use this bitmap and return whether or not the memory is zero filled.
  62   BitMap _dirty;
  63 
  64   // Indicates that the entire space has been committed and pinned in memory,
  65   // os::commit_memory() or os::uncommit_memory() have no function.
  66   bool _special;
  67 
  68   // Indicates whether the committed space should be executable.
  69   bool _executable;
  70 
  71   // Commit the given memory range by using _commit_size pages as much as possible
  72   // and the remainder with small sized pages. The start address must be _commit_size
  73   // aligned.
  74   void commit_internal(char* start, char* end);
  75   // Uncommit the given memory range.
  76   void uncommit_internal(char* start, char* end);
  77 
  78   // Returns the index of the page which contains the given address.
  79   uintptr_t  addr_to_page_index(char* addr) const;
  80   // Returns the address of the given page index.
  81   char*  page_start(uintptr_t index);
  82   // Returns the address of the end of the page given the page index ranging
  83   // from 0..size_in_pages-2. For the last page, return _high_boundary.
  84   char*  page_end(uintptr_t index);
  85 
  86   // Returns true if the entire area is backed by committed memory.
  87   bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
  88   // Returns true if the entire area is not backed by committed memory.
  89   bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  90 
  91  public:
  92 
  93   // Commit the given area of pages starting at start being size_in_pages large.
  94   // Returns true if the given area is zero filled upon completion.
  95   bool commit(uintptr_t start, size_t size_in_pages);
  96 
  97   // Uncommit the given area of pages starting at start being size_in_pages large.
  98   void uncommit(uintptr_t start, size_t size_in_pages);
  99 
 100   // Initialization
 101   G1PageBasedVirtualSpace();
 102   // Initialize the given reserved space with the given base address and actual size.
 103   // Prefer to commit in commit_size chunks.
 104   bool initialize_with_granularity(ReservedSpace rs, size_t actual_size, size_t commit_size);
 105 
 106   // Destruction
 107   ~G1PageBasedVirtualSpace();
 108 
 109   // Amount of reserved memory.
 110   size_t reserved_size() const;
 111   // Memory used in this virtual space.
 112   size_t committed_size() const;
 113   // Memory left to use/expand in this virtual space.
 114   size_t uncommitted_size() const;
 115 
 116   bool contains(const void* p) const;
 117 
 118   MemRegion reserved() {
 119     MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
 120     return x;
 121   }
 122 
 123   void release();
 124 
 125   void check_for_contiguity() PRODUCT_RETURN;
 126 
 127   // Debugging
 128   void print_on(outputStream* out) PRODUCT_RETURN;
 129   void print();
 130 };
 131 
 132 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
--- EOF ---