linux kernel中eventfd的使用

什么是eventfd?

An “eventfd object” can be used as an event wait/notify mechanism by user-space applications, and by the kernel to notify user-space applications of events. It has been added to kernel since Linux 2.6.22. 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.