I am warming up to netmap but I want to deploy on Linux without distributing a kernel module.

Snabb Switch still uses its own built-in device drivers but if that was not an option I reckon we would be more likely to adopt netmap than DPDK because it is so much simpler.

From: https://patchwork.ozlabs.org/patch/396713/

  From: Daniel Borkmann
  ...
  With 1 core netmap does 10G line-rate on 64b; I don't
  know their numbers on 40G when run on decent hardware though.

So looks like netmap has not only nice API, driver-specific code is trivial, but also the performance might be good. If only netmap could do the "bifurcated driver" use case!

Last time I looked there was no way to limit access - if you have access to one netmap network device you have access to all of them.

Also check out Vale high performance network stack by the same group.

http://info.iet.unipi.it/~luigi/netmap/

I've seen netmap referenced occasionally over the years, but I've never actually seen anyone using it in the real world. Anyone have any links to projects/companies which use it?

Probably because it's in use on BSD-based network appliances you don't have access to look inside. It would be great for anti-DDoS and IPS/IDS devices.

It gets used in large high-throughput systems.

Just not a lot of need elsewhere, and most of those networks are running proprietary code, so you don't see much about it.