Here's an interesting kqueue v epoll benchmark I picked up somewhere when this t...

trentnelson · on June 17, 2015

Registered I/O on Windows is about three to four decades ahead, conceptually.

(As in, the stuff that facilitates registered I/O is based on concepts that can be traced back to VMS, released in 1977. Namely, the Irp, plus, a kernel designed around waitable events, not runnable processes.)

15155 · on June 17, 2015

kqueue allows more sophisticated action to occur with each call.

epoll requires more syscalls to do the same stuff.

that's not responsible for the differences speed, but at this level syscalls are a meaningful expense.