diff -r 13dbe89e447c -r 8ba0078861d4 src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp	Fri Sep 26 20:09:02 2014 -0700
+++ b/src/share/vm/runtime/arguments.cpp	Sat Sep 27 15:11:41 2014 +0200
@@ -1646,6 +1646,12 @@
                      Abstract_VM_Version::parallel_worker_threads());
   }
 
+#if INCLUDE_ALL_GCS
+  if (G1ConcRefinementThreads == 0) {
+    FLAG_SET_DEFAULT(G1ConcRefinementThreads, ParallelGCThreads);
+  }
+#endif
+
   // MarkStackSize will be set (if it hasn't been set by the user)
   // when concurrent marking is initialized.
   // Its value will be based upon the number of parallel marking threads.