fedora 14 kernel performance with ip forwarding workload
Arnaldo Carvalho de Melo
acme at ghostprotocols.net
Wed Apr 6 20:13:05 UTC 2011
Em Wed, Apr 06, 2011 at 01:02:39PM -0700, David Miller escreveu:
> From: Arnaldo Carvalho de Melo <acme at 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.
cool, these code modification and JIT mechanizms open up a lot of
possibilities indeed ;-)
> 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:
<SNIP>
> I suspect Jesse has something similar on his test box.
>
> When no rules are loaded, all the stubs make happen is a function call
> plus a list_empty() check. Nothing more. I really can't see that, all
> by itself, obliterating routing performance.
Yeah, would be nice, since he is playing with it, for him to post
numbers about the overheads.
> In fact I've done udp flood tests, as recently as a month ago, with just
> NETFILTER=y and no rules installed, and the impact was minimal.
>
> And that was on sparc64 where function calls are expensive :)
:-)
- Arnaldo
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