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

*** 263,285 ****
    // OS interface to Virtual Memory
  
    // Return the default page size.
    static int    vm_page_size();
  
!   // Return the page size to use for a region of memory.  The min_pages argument
!   // is a hint intended to limit fragmentation; it says the returned page size
!   // should be <= region_max_size / min_pages.  Because min_pages is a hint,
!   // this routine may return a size larger than region_max_size / min_pages.
!   //
!   // The current implementation ignores min_pages if a larger page size is an
!   // exact multiple of both region_min_size and region_max_size.  This allows
!   // larger pages to be used when doing so would not cause fragmentation; in
!   // particular, a single page can be used when region_min_size ==
!   // region_max_size == a supported page size.
!   static size_t page_size_for_region(size_t region_min_size,
!                                      size_t region_max_size,
!                                      uint 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];
    }
--- 263,277 ----
    // OS interface to Virtual Memory
  
    // 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);
! 
    // 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];
    }