Subject: Re: [PATCH net-next 3/6] flow_dissector: Add hash_extra field to flow_keys struct

From: Florian Westphal <[email-masked]>
Date: Sun, 1 Mar 2015 20:43:48 +0100

Tom Herbert <[email-masked]> 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.