We have implemented a prototype exokernel operating system.
Measurements show that most primitive kernel operations (such
as exception handling and protected control transfer) are ten to 100
times faster than in Ultrix, a mature monolithic UNIX operating system.
In addition, we demonstrate that an exokemel allows applications
to control machine resources in ways not possible in traditional
operating systems. For instance, virtual memory and interprocess
communication abstractions are implemented entirely within an
application-level library. Measurements show that application-level
virtual memory and interprocess communication primitives are five
to 40 times faster than Ultrix’s kernel primitives. Compared to
state-of-the-art implementations from the literature, the prototype
exokemel system is at least five times faster on operations such as
exception dispatching and interprocess communication.