src/share/vm/runtime/os.hpp

rev 7180 : 8067469: G1 ignores AlwaysPreTouch
Summary: Factor out pretouch code of the various virtual space management classes and use them everywhere including in G1.
Reviewed-by: stefank, ehelin, dholmes
rev 7181 : 8049864: TestParallelHeapSizeFlags fails with unexpected heap size
Reviewed-by: sjohanss, jmasa
rev 7183 : 8066875: VirtualSpace does not use large pages
Reviewed-by: stefank, tschatzl, anoll, thartmann

@@ -147,10 +147,11 @@
                              bool allow_exec);
   static bool   pd_unmap_memory(char *addr, size_t bytes);
   static void   pd_free_memory(char *addr, size_t bytes, size_t alignment_hint);
   static void   pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint);
 
+  static size_t page_size_for_region(size_t region_size, size_t min_pages, bool must_be_aligned);
 
  public:
   static void init(void);                      // Called before command line parsing
   static void init_before_ergo(void);          // Called after command line parsing
                                                // before VM ergonomics processing.

@@ -265,12 +266,17 @@
   // Return the default page size.
   static int    vm_page_size();
 
   // Returns the page size to use for a region of memory.
   // region_size / min_pages will always be greater than or equal to the
-  // returned value.
-  static size_t page_size_for_region(size_t region_size, size_t min_pages);
+  // returned value. The returned value will divide region_size.
+  static size_t page_size_for_region_aligned(size_t region_size, size_t min_pages);
+
+  // Returns the page size to use for a region of memory.
+  // region_size / min_pages will always be greater than or equal to the
+  // returned value. The returned value might not divide region_size.
+  static size_t page_size_for_region_unaligned(size_t region_size, size_t min_pages);
 
   // Return the largest page size that can be used
   static size_t max_page_size() {
     // The _page_sizes array is sorted in descending order.
     return _page_sizes[0];