Kqueue

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Kqueue is a scalable event notification interface that first appeared in FreeBSD 4.1. Kqueue enables the user to receive alerts regarding events on specified targets very quickly. NetBSD, OpenBSD and Darwin also include Kqueue ports. Kqueue provides efficient input and output event pipelines between the kernel and userland. Thus, it is possible to modify event filters as well as receive pending events while using only a single system call to kevent(2) per main event loop iteration. This contrasts with older traditional polling system calls such as poll(2) and select(2) which are less efficient, especially when polling for events on a large number of file descriptors.