Small correction: DDIO is not limited to Intel NICs, it's a mostly-transparent-to-the-hardware mechanism by which DMAs are snooped and some fraction of the NIC-

Small correction: DDIO is not limited to Intel NICs, it's a mostly-transparent-to-the-hardware mechanism by which DMAs are snooped and some fraction of the NIC-local (in the case of multi socket systems) L3 cache is filled with incoming data.