--- a/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp	Wed Dec 17 18:09:24 2014 +0100
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp	Thu Dec 18 09:37:02 2014 +0100
@@ -131,6 +131,9 @@
   _committed.set_range(start, start + size_in_pages);
 
   MemRegion result((HeapWord*)page_start(start), byte_size_for_pages(size_in_pages) / HeapWordSize);
+  if (AlwaysPreTouch) {
+    os::pretouch_memory((char*)result.start(), (char*)result.end());
+  }
   return result;
 }