FreeBSD box as router adding latency

Aloha Guy alohaguy123 at
Thu Feb 26 13:53:44 PST 2004

Chris Dillon <cdillon at> wrote: 
On Wed, 25 Feb 2004, Aloha Guy wrote:

> You're right that additional delay while adding a hop is to be
> expected, which is less than 0.1ms to the FreeBSD box but everything
> past the FreeBSD machine is adding atleast 5ms up to 300ms in the
> traceroutes when the normal is no more than 20ms for the same
> traceroute. I've already checked the NICs and they are all
> configured at their full rated speeds and full duplex. I even try
> using a Cardbus PCMCIA fxp0 Intel Pro/100S card on the FreeBSD box
> and it still had the same problem. I am using a September 2003
> -CURRENT so I don't know if it's a issue with the current networking
> code back then or not.

What do you have HZ set to (see sysctl kern.clockrate)? I think I
remember your original message showing you using pipes and queues and
the HZ setting can affect those. Also see if your latency improves if
you remove all pipe and queue rules (other ipfw rules are OK).

Here is the HZ setting: 

kern.clockrate: { hz = 100, tick = 10000, profhz = 1024, stathz = 128 }

I'm not sure how to remove the pipe since I don't think the pipe works until the queue is defined.  When I removed the queues that are configured for the pipe, the latency is back to normal though. 



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