Profile-directed restructuring of operating system code

In this paper we describe how a profiling system can be successfully used to restructure the components of an operating system for improved overall performance. We discuss our choice of a profiling system and how it was applied to the AS/400® (Application System/400®) operating system for the purpose of reordering code. Previous work in the industry has been mainly useful only for application programs. Our work demonstrates how such techniques can be applied to operating system code, while preserving maintainability of the operating system in the customer's environment.