SR-IOV: Using both PF and VFs

Hey,

I created 2 VFs on a 10 Gigabit port (Intel 82599 10 Gigabit NIC).

Should only VFs be used as 2 5-Gigabit virtual ports?

Or PF is also usable? If it is, then if I use both PF and VFs - each of them gets 3.33-Gigabit of throughput?

Can I assign both PF and VFs to a single VM?

What is the recommeded use?

Thanks,

Shaham