mental ray:
RC 0.2 info : type number per eye ray
RC 0.2 info : eye rays 971978 1.00
RC 0.2 info : shadow rays 458468 0.47
rendering time: 9 seconds
elvish ray:
number of eye rays: 867168
number of shadow rays: 427724
shadow rays per eye ray: 0.493242
rendering time: 5 seconds