Re: why does netfilter make upload very slow? (was: Re: e1000 -> 82540EM on linux 2.6.0-test[45] very slow in one direction)

Harald Welte wrote:

quoted

Would somebody like to explain why netfilter (in kernel, but not in use)
makes upload go very slow? I am by no means a network guru, but eager to
learn :-)

let's get this straight.  There are five possible cases

a) CONFIG_NETFILTER disabled.  you won't even have the netfilter hooks
   in the network stack (so certainly no netfilter-using modules loaded)

no problem

b) CONFIG_NETFILTER enabled, but _no_ modules (iptable_filter,
   ip_conntrack, ...) attached to the netfilter hook

no problem

c) CONFIG_NETFILTER enabled and iptable_filter.o (which pulls ip_tables.o)
   loaded, NO RULES in the table

no problem

d) CONFIG_NETFILTER enabled and iptable_filter.o (which pulls ip_tables.o)
   loaded, RULES in the table

no problem (as long as i dont load any rules that require ip_conntrack)

e) CONFIG_NETFILTER enabled and ip_conntrack.o loaded, iptable_filter
   loaded or not, rules or not

*boink*

whenever i try to load ip_conntrack the nic performance drops from 5mb/s 
to 200k/s.

still using 2.6.0-test6.

regards,
Florian