src/share/vm/runtime/virtualspace.cpp

rev 7555 : imported patch 8067469-g1-ignores-alwayspretouch

*** 613,635 ****
        _upper_high += upper_needs;
      }
    }
  
    if (pre_touch || AlwaysPreTouch) {
!     int vm_ps = os::vm_page_size();
!     for (char* curr = previous_high;
!          curr < unaligned_new_high;
!          curr += vm_ps) {
!       // Note the use of a write here; originally we tried just a read, but
!       // since the value read was unused, the optimizer removed the read.
!       // If we ever have a concurrent touchahead thread, we'll want to use
!       // a read, to avoid the potential of overwriting data (if a mutator
!       // thread beats the touchahead thread to a page).  There are various
!       // ways of making sure this read is not optimized away: for example,
!       // generating the code for a read procedure at runtime.
!       *curr = 0;
!     }
    }
  
    _high += bytes;
    return true;
  }
--- 613,623 ----
        _upper_high += upper_needs;
      }
    }
  
    if (pre_touch || AlwaysPreTouch) {
!     os::pretouch_memory(previous_high, unaligned_new_high);
    }
  
    _high += bytes;
    return true;
  }