VNET performance

[Clint Armstrong]

What is the expected network performance of a VNET jail for network
communication between the jail and the host, or between multiple jails? I
expected it to approach the 10Gbps of the epair device, but I'm not seeing
that.

I see between 800 - 1200 Mbps in standard iperf tests both between the host
bridge interface and the vnet jail inteface. I see the same poor speeds if
I make 2 vnet jails and put one side of the epair in each and test between
them.

Is the overhead of vnet causing this? Is there anything I can do to improve
this performance.

I've tested and seen similar performance on 10.0-RELEASE and 11.0-CURRENT.