l try it again with 10gbps early next year once back in 
> the office again.  The more interesting transition is between the link 
> layer and the network layer, which is high on my list of topics to look 
> into in the next few weeks.  In particular, reworking the ifqueue 
> handoff.  The tricky bit is balancing latency, overhead, and concurrency...
> 
> FYI, there are several sets of patches floating around to modify if_em 
> to hand off queues of packets to the link layer, etc.  They probably 
> need updating, of course, since if_em has changed quite a bit in the 
> last year.  In my implementaiton, I add a new input routine that accepts 
> mbuf packet queues.
> 

Have you tested this with more than just your simple netblast and 
netperf tests?  Have you measured CPU usage during your tests?  With 
10Gb coming, pipelined processing of RX packets is becoming an 
interesting topic for all OSes from a number of companies.  I understand
your feeling about the bottleneck being higher up than at just if_input.
We'll see how this holds up.

Scott