Help: FreeBSD 6.3 - em driver & taskqueue & priority

Joe Kuan joe.kuan at
Tue Jul 8 11:08:45 UTC 2008

Hi all,

    I have implemented an network application in kernel space and it  
is working fine. The application involves 3 network interfaces that  
FreeBSD 6.3 can forward mbuf between em0 and em1 in a rate 1.3 - 1.4  
millions packets per second. Em2 is used for controlling the network  

    The problem is that when em0 and em1 are transmitting in 1.3 - 1.4  
millions packets per second, the em2 interface becomes irresponsive.  
However, my goal is to make the kernelised network application  
response as soon as a control packet arrives in em2, ie jumps the  
queue ahead of all the packets in em0 and em1.

    I think the problem lies on the priority set on the task structure  
are all the same for all the em devices. Am I heading in the right  

    If not, please advise me.

Many thanks in advance

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