On: One Million Concurrent TCP connections

[gorset]

That's actually accept_filter(9). The man page for freebsd has a interesting info:

    The accept filter concept was pioneered by David Filo at Yahoo! and
    refined to be a loadable module system by Alfred Perlstein.

The closest you can get by using kqueue is to set a low water mark, so that a read event is only returned when there's enough data ready.

[Flow → gorset]

Ah, that's it! Thanks for finding it.