Tom Herbert [off-list ref] wrote:

We still need hash perturbation for the mapping to a small number of
queues which can be done after retrieving skb_get_hash, but the
probability that two different flows match perfectly in skb_get_hash()
should be 1/2^32-- so are hash collisions really a concern here?

I'm not concerned about accidental collisions, how predictable is skb_get_hash()?
Is skb_get_hash() guaranteed to e.g. contain L4 information?

AFAIK answer to both is "depends on nic/driver", so I feel its better to use
software flow dissector.