FreeBSD 7.1 taskq em performance

[Joseph Kuan]

Hi all,
  I have been hitting some barrier with FreeBSD 7.1 network performance. I
have written an application which contains two kernel threads that takes
mbufs directly from a network interface and forwards to another network
interface. This idea is to simulate different network environment.

  I have been using FreeBSD 6.4 amd64 and tested with an Ixia box
(specialised hardware firing very high packet rate). The PC was a Core2 2.6
GHz with dual ports Intel PCIE Gigabit network card. It can manage up to 1.2
million pps.

  I have a higher spec PC with FreeBSD 7.1 amd64 and Quadcore 2.3 GHz and
PCIE Gigabit network card. The performance can only achieve up to 600k pps.
I notice the 'taskq em0' and 'taskq em1' is solid 100% CPU but it is not in
FreeBSD 6.4.

  Any advice?

  Many thanks in advance

  Joe