Re: fedora 14 kernel performance with ip forwarding workload

[Eric Dumazet <eric.dumazet@gmail.com>]

Le mercredi 06 avril 2011 à 13:02 -0700, David Miller a écrit :
> From: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Date: Wed, 6 Apr 2011 16:57:19 -0300
> 
> > Something like ftrace code changing when the user inserts the first
> > rule?
> > 
> > People wanting top performance disable it in the build, but thos wanting
> > to stick to vendor provided kernels don't have that choice :)
> 
> Using ftrace-like stubs would be an interesting idea, and I highly encourage
> people to work on something like that.
> 
> However I want to reiterate that I think that real rules are installed
> in Jesse's case, and once he removes those the majority of the
> overhead will disappear.  The FC14 workstation I'm using right now, on
> which I've made no modifications to the installer's netfilter settings,
> has the following rules:
> 
> --------------------
> [root@ilbolle davem]# iptables -L
> Chain INPUT (policy ACCEPT)
> target     prot opt source               destination         
> ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED 
> ACCEPT     icmp --  anywhere             anywhere            
> ACCEPT     all  --  anywhere             anywhere            
> ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ssh 
> ACCEPT     udp  --  anywhere             anywhere            state NEW udp dpt:ipp 
> ACCEPT     udp  --  anywhere             224.0.0.251         state NEW udp dpt:mdns 
> ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp dpt:ipp 
> ACCEPT     udp  --  anywhere             anywhere            state NEW udp dpt:ipp 
> REJECT     all  --  anywhere             anywhere            reject-with icmp-host-prohibited 
> 
> Chain FORWARD (policy ACCEPT)
> target     prot opt source               destination         
> REJECT     all  --  anywhere             anywhere            reject-with icmp-host-prohibited 
> 
> Chain OUTPUT (policy ACCEPT)
> target     prot opt source               destination         
> [root@ilbolle davem]# 
> --------------------
> 
> I suspect Jesse has something similar on his test box.
> 

I suspect problem is worse than that.

I remember last time I work on a fedora kernel, it had conntrack enabled

And yes, conntrack can really slowdown a router, because of default
parameters.

cat /proc/sys/net/nf_conntrack_max