我们如何知道对epoll_wait（）的调用是边缘触发还是水平触发？

Question

我知道指定事件EPOLLET会将epoll从水平触发切换到边缘触发。 这是否意味着默认情况下调用epoll_wait()是水平触发？

Answer 1

请参阅http://man7.org/linux/man-pages/man7/epoll.7.html

By contrast, when used as a level-triggered interface (the default,
when EPOLLET is not specified), epoll is simply a faster poll(2), and
can be used wherever the latter is used since it shares the same
semantics.

因此，当未指定EPOLLET时，水平触发是默认选项。