From: Ralph Doncaster <ralph@xxxxxxxxx>
Date: Tue, 10 Jun 2003 17:39:44 -0400 (EDT)
Looking at Simon's profile numbers, these seem to contribute a lot more
Ignore all the fib_rule*() and associated overhead, Simon
is going to turn of policy routing support so that stuff
drops out of the profiles.
The fib_lookup() will decrease significantly from the profiles
if fib_validate_source() is deleted, and this is what I want
confirmed from such an experiment.
1237 ipt_route_hook 19.3281
3120 do_gettimeofday 21.6667
8299 ip_packet_match 24.6994
8031 fib_lookup 25.0969
1877 fib_rule_put 29.3281
What's the do_gettimeofday for?
Every packet records a timestamp.
I traced back the fib_lookup to ip_forward_finish, which seems to only
call ip_forward_options when there's IP options (go figure!), which would
make sense for a SYN packet (juno).
You're thinking TCP options, not IP options.
What I can't think of is why we'd want to have special routing
considerations for TCP SYN packets (and other IP packets with
ip_forward_options() has to update things like record-route
IP options, which record hop-by-hop information for diagnostic
tools like traceroute.