EVBACKEND_EPOLL
if (EV_USE_EPOLL ) flags |= EVBACKEND_EPOLL;
int flags = EVBACKEND_EPOLL | EVBACKEND_KQUEUE | EVBACKEND_PORT;
flags &= ~EVBACKEND_EPOLL;
if (!backend && (flags & EVBACKEND_EPOLL )) backend = epoll_init (EV_A_ flags);
if (backend == EVBACKEND_EPOLL ) epoll_destroy (EV_A);
if (backend == EVBACKEND_EPOLL ) epoll_fork (EV_A);