tinc throughput on alix machines

[michael-dev]

Hi,

I've setup a wlan ap using a an alix 2d2 (AMD Geode LX 500 Mhz + AES
Offload)
and am now trying to encapsulate the wlan traffic into a vpn (tap bridge).
Though even when disabling crypto and digest (there is a crypto engine
onboard 
can be setup to handle tinc encryption), the best throughput I get
is aroung 2,9 MByte per second (wget+http) (even if the client is run
locally).
The network card and the source do support up to 11 MByte/s and when using
tinc
the cpu loads go into the limits, so I guess to just copying memory or
calculating way too much.
Looking at the source, it looks like there isn't much copying at all,
the only place it wasn't clear to me why copying occurs is at the
beginning in route_mac
when source and destination mac are copying into local variables, though
changing that does
not gain a lot. Running gprof it reports no time spent but only function
calls, which
hints that all time is lost in the kernel.

Does somebody have any numbers around on what one could expect on a 500
Mhz machine
using tinc with/without encryption or on what to try out to improve
throughput?

Thanks a lot,
 Michael Braun