kttcp —
kernel support for testing network throughput
This driver provides kernel support for testing network throughput from the
  perspective of the kernel. It is similar in spirit to the classic ttcp network
  benchmark program, the main difference being that with kttcp, the kernel is
  the source and sink of the data.
Testing like this is useful for a few reasons:
  - This allows us to know what kind of performance we can expect from network
      applications that run in the kernel space, such as the NFS server or the
      NFS client. These applications don't have to move the data to/from
      userspace, and so benchmark programs which run in userspace don't give us
      an accurate model.
- Since data received is just thrown away, the receiver is very fast. This
      can provide better exercise for the sender at the other end.
- Since the NetBSD kernel currently uses a
      run-to-completion scheduling model, kttcp provides a benchmark model where
      preemption of the benchmark program is not an issue.
pkgsrc/benchmarks/kttcp,
  pkgsrc/benchmarks/ttcp