IPFW questions

[Staffan Ulfberg]

I've played around a bit more with my 300 MHz firewall now.  Actually,
even if I completely disable natd, and use only a single pass-all
firewall rule, I can't get over about 30 MBps, at 2500 packets per
second, through the machine.  (I used netstat -i -b to measure
traffic.)

I tried the link0 option for both interfaces (fxp), which helped only
slightly.  (If anyone remembers the original post, I'm testing by
transferring files from fxp1 to fxp3.)

I also tried compiling a kernel with DEVICE_POLLING.  At 500 Hz,
routing performance is about the same as with normal interrupts, but
with slightly better overall system response.  Over that (tried 1000,
2000 Hz) and the system is very unresponsive and I believed it had
hanged several times (but it hadn't).

BTW, can anyone tell me why the system clock gets slowed down a factor
of two or more when using DEVICE_POLLING?  (And, of course, if there's
a fix...)

Is this machine simply too slow to use even as a simple router for 100
Mbps traffic?  I must say I'm a bit surprised.  Or any tuning
suggestions?

Staffan