Flow ID, LACP, and igb

[T.C. Gubatayao]

> No problem with fnv_hash().

Doesn't it have bad mixing?  Good distribution is important since this code is
for load balancing.

FNV is also slower compared to most of the newer non-cryptographic hashes,
certainly on large keys, but even on small ones.  Of course, performance will
vary with the architecture.

> While I agree that it is likely that siphash24() is slower if you could afford
> the time do a test run it would be great to from guess to know.

+1

You might want to consider lookup3 too, since it's also readily available in the
kernel [1].

T.C.

[1] http://svnweb.freebsd.org/base/head/sys/libkern/jenkins_hash.c?view=markup