NIC rx/tx ring size vs XSK rx/tx ring size

Hello,

Please what is the relation between NIC ring sizes and XDP socket ring sizes?
If my app sets XDP_RX_RING and XDP_TX_RING, what are the optimal values for ethtool -G rx/tx?

Also I don't understand why changing TX ring size changes some XDP ring size for the ice driver (Kernel 5.13):
[  424.542118] ice 0000:41:00.0 enp65s0f0: Changing Tx descriptor count from 256 to 2048
[  424.542176] ice 0000:41:00.0 enp65s0f0: Changing XDP descriptor count from 256 to 2048   <- What is that?

In the case of the i40e driver, there is no XDP ring logged:
[847243.925269] i40e 0000:81:00.0 enp129s0f0: Changing Tx descriptor count from 256 to 2048.

Thank you,
Daniel