The licensed internal code (LIC) does not include SIE IOASSIST for the V=R
guest when the VM/ESA ESA Feature is running natively on it.The absence of
the assist does not change the behavior of the guest, but it effects the overall
performance offered when compared with other S/390 processors.IOASSIST
can also be turned off by the customer on an ES/9000 or other VM/ESA
supported processors.
Appendix A.Performance33