ev_select.c only when select backend is enabled (which is by default)
ev_poll.c only when poll backend is enabled (disabled by default)
ev_epoll.c only when the epoll backend is enabled (disabled by default)
ev_select.c only when select backend is enabled (which is by default)
ev_poll.c only when poll backend is enabled (disabled by default)
ev_epoll.c only when the epoll backend is enabled (disabled by default)