[$] A kernel event notification mechanism

The kernel has a range of mechanisms for notifying user space whensomething of interest happens. These include dnotify and inotify for filesystem events,signals, poll(), tracepoints, uevents, and more. One might think thatthere would be little need for yet another, but there are still events ofinterest that user space can only learn about by polling. In an attempt tofix this problem, David Howells, not content with his recent attempt to add seven new system calls for filesystemmounting, has put forward a proposal for ageneral-purpose event notification mechanism for Linux.