https://github.com/deadtrickster/eventfd.git
git clone 'https://github.com/deadtrickster/eventfd.git'
(ql:quickload :eventfd)
eventfd() creates an “eventfd object” that can be used as an event wait/notify mechanism by user-space applications, and by the kernel to notify user-space applications of events. The object contains an unsigned 64-bit integer (uint64_t) counter that is maintained by the kernel. This counter is initialized with the value specified in the argument initval.