An ontology and constraint based approach to cache preloading

The verification of modern microprocessor-based systems requires stressing the cache hierarchy and effectively covering its huge state space. Cache hierarchy initialization (or preloading) is a technique that enables simulation to start from a rich, complex system-level setup, thereby simplifying the task of dynamically driving the hierarchy into the required corner cases. In this paper we introduce CacheLoader, a new, design-independent cache-preloading technology. The tool's architecture follows the principles of ontology-based software to achieve complete separation between the cache-preloading engine and design dependent knowledge. Constraint satisfaction techniques are used to generate valid, interesting system initialization, and to satisfy explicit user directives. CacheLoader is currently being used by verification teams of several large scale designs in IBM. Results show that this technique provides superior coverage and user controllability, speeds up the construction of mature verification environments, simplifies maintenance, encourages encapsulation of domain knowledge, and enables reuse across verification environments and cache hierarchy designs.