Communication patterns [message-passing patterns]

Parallel applications have message-passing patterns that are important to understand. Network topology, routing decisions, and connection and buffer management need to match the communication patterns of an application for it to run efficiently and scale well. These patterns are not easily discerned from the source code of an application, and even when the data is available it is not easy to categorize it appropriately such that meaningful knowledge emerges. We describe a novel system to gather the information we need to discover an application´s communication pattern. We create five categories that help us analyze that data and explain how information from each category can be useful in the design of networking hardware and software. We use the NAS parallel benchmarks as examples on how to apply our techniques