--- a/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp Thu Apr 02 16:42:24 2015 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp Tue Apr 07 10:53:51 2015 +0200
@@ -34,6 +34,12 @@
// 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 page size.
+// The actual size requested need not be aligned to that page size, but the size
+// of the reservation passed may be rounded up to this page size. Any fragment
+// (less than the page 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 {
@@ -43,7 +49,11 @@
char* _low_boundary;
char* _high_boundary;
- // The commit/uncommit granularity in bytes.
+ // The size of the tail in bytes of the handled space that needs to be committed
+ // using small pages.
+ size_t _tail_size;
+
+ // The preferred page size used for commit/uncommit in bytes.
size_t _page_size;
// Bitmap used for verification of commit/uncommit operations.
@@ -62,30 +72,55 @@
// Indicates whether the committed space should be executable.
bool _executable;
+ // Helper function for committing memory. Commit the given memory range by using
+ // _page_size pages as much as possible and the remainder with small sized pages.
+ void commit_internal(size_t start_page, size_t end_page);
+ // Commit num_pages pages of _page_size size starting from start. All argument
+ // checking has been performed.
+ void commit_preferred_pages(size_t start_page, size_t end_page);
+ // Commit space at the high end of the space that needs to be committed with small
+ // sized pages.
+ 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(uintptr_t index);
- // Returns the byte size of the given number of pages.
- size_t byte_size_for_pages(size_t num);
+ char* page_start(size_t index) const;
+
+ // Is the given page index the last page?
+ bool is_last_page(size_t index) const { return index == (_committed.size() - 1); }
+ // Is the given page index the first after last page?
+ bool is_after_last_page(size_t index) const;
+ // Is the last page only partially covered by this space?
+ bool is_last_page_partial() const { 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) const;
// Returns true if the entire area is backed by committed memory.
- bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
+ bool is_area_committed(size_t start_page, 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;
+ bool is_area_uncommitted(size_t start_page, 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(uintptr_t start, size_t size_in_pages);
+ bool commit(size_t start_page, 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);
+ void uncommit(size_t start_page, size_t size_in_pages);
- // Initialization
- G1PageBasedVirtualSpace();
- bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
+ // 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();