r284988:
cxgbe(4): request an automatic tx update when a netmap tx queue idles.
The NIC tx queues already do this.
r285220:
cxgbe(4): Do not override the the global defaults for congestion drops.
The hw.cxgbe.cong_drop knob is not affected by this change because the
driver sets up congestion drop on a per-queue basis.
r285221:
cxgbe(4): Add a new knob that controls the congestion response of netmap
rx queues. The default is to drop rather than backpressure.
This decouples the congestion settings of NIC and netmap rx queues.
84fadb8369