epoll_create - 打开一个epoll的文件描述符
int epoll_create(int size)
Open an epoll file descriptor by requesting the kernel allocate an event backing store dimensioned for size descriptors. The size is not the maximum size of the backing store but just a hint to the kernel about how to dimension internal structures. The returned file descriptor will be used for all the subsequent calls to the epoll interface. The file descriptor returned by epoll_create(2) must be closed by using close(2).
When successful, epoll_create(2) returns a non-negative integer identifying the descriptor. When an error occurs, epoll_create(2) returns -1 and errno is set appropriately.
|EINVAL||size is not positive.|
|ENFILE||The system limit on the total number of open files has been reached.|
|ENOMEM||There was insufficient memory to create the kernel object.|
epoll_create(2) 在Linux内核2.5.44 推出了一个新的API。该接口应该由Linux kernel 2.5.66。