The principal difference between the libphenom event dispatcher and the other event libraries is that libphenom can wakeup and dispatch IO events to any of the IO scheduling threads (no thread affinity).

Contrast with the libevent approach of using an application specific scheme to assign descriptors to an event base associated with a thread (strong thread affinity).

This makes more of a difference if you have chatty protocols and/or long lived sessions and no way to rebalance your fd -> event_base mapping.