Performance analysis on a CC-NUMA prototype

Cache-coherent nonuniform memory access (CC-NUMA) machines have been shown to be a promising paradigm for exploiting distributed execution. CC-NUMA systems can provide performance typically associated with parallel machines, without the high cost associated with parallel programming. This is because a single image of memory is provided on a CC-NUMA machine. Past research on CC-NUMA machines has focused on modifications to the memory hierarchy, interconnect topology, and memory consistency protocols, which are all areas critical to achieving scalable performance. The research described here expands this focus to issues associated with operating system structures which can increase system scalability. We describe a hardware/software prototyping study which investigates how changes to the operating system of a commercial IBM AS/400® system can provide scalable performance when running transaction processing workloads. The project described was a joint effort between researchers at the IBM Thomas J. Wats on Research Center and a team from the AS/400 development laboratory in Rochester, Minnesota. This paper describes various aspects of the project, including changes made to the operating system to enable scalable performance, and the associated hardware and software performance tools developed to identify bottlenecks in the existing operating system structures.