>So, then, what does kqueue buy us, exactly?

It lets you write really _big_ nonthreaded apps, with low latency,
without the overhead of copying huge bitvectors or huge pollsets in
and out of the kernel.  (Think tens of thousands of open sockets.)

And its cleaner than similar-performing alternatives (e.g., the Usenix
paper by Gaurav Banga and Jeff Mogul).