Changes in the network interface queueing handoff model

[Petri Helenius]

Robert Watson wrote:
>
> I tend to agree, but implemented full queueing support for if_em to 
> make sure I understood to complexity implications of completely 
> removing queueing from the ifnet side dispatch.  I guess an 
> interesting question for us is how we decide what the right threshold 
> is to implement software queuing.  Do any if_em cards need software 
> queueing, or do they all have adequate in-hardware queues as is?  
> Entirely cutting the queue code would significantly simplify 
> em_startmbuf.
Actually most em cards support 4096 descriptors each way.

Pete