The Morph system provides a framework for automatic collection and management of profile information and application of profile-driven optimizations. In this paper, we focus on the operating system support that is required to collect and manage profile information on an end-user's workstation in an automatic, continuous, and transparent manner. Our implementation for a Digital Alpha machine running Digital UNIX 4.0 achieves run-time overheads of less than 0.3% during profile collection. Through the application of three code layout optimizations, we further show that Morph can use statistical profiles to improve application performance. With appropriate system support, automatic profiling and optimization is both possible and effective.

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