From: Alexander Duyck <redacted>
Date: Thu, 26 Jul 2012 19:14:55 -0700

Any idea why these look-ups are so expensive in the first place?  When
I dump fib_trie it doesn't look like I have much there.  I would have
thought the table would be pretty static with just 8 flows all going
to the same destination address, but it seems like I was getting hit
with cache misses for some reason.

A lot of the overhead comes from write traffic that results from
filling in the "fib_result" structure onto the callers stack.

The return value from a fib_lookup() has far too many components.  But
simplifying things is not easy.