Binary package “apache2-mpm-event” in ubuntu precise

Apache HTTP Server - event driven model

 Each Apache Multi-Processing Module provides a different "flavor" of
 web server binary, compiled with a different processing model.
 The event MPM is designed to allow more requests to be served
 simultaneously by passing off some processing work to supporting
 threads, freeing up the main threads to work on new requests. It is
 especially suitable for sites that see extensive KeepAlive traffic.
 This MPM is experimental and less tested than the worker and prefork MPMs.