Program specialization using the OMOS system

Abstraction and modularity provide many software engineering benefits. Hiding details of module internals can, however, prevent system implementors from being able to provide anything but a highly general implementation of a given module. We describe OMOS, a programmable linker/loader and system server that manages module implementations. OMOS allows system builders to describe system architectures in high-level terms, via a module construction scripting language. Using scripts, system implementors can provide modules that can test and react to both their static and run time environments. These modules, which we refer to as electric libraries, can produce implementations that are optimized at link or run time, without sacrificing modularity, expanding interfaces, or requiring changes in client programs. We identify and implement three types of specializations that OMOS can perform, and quantify the impact of two of them on a few standard Unix utilities: performance improvements ranged from 6% to 47%.?