NUMA-aware Scalable Graph Traversal on SGI UV Systems

Breadth-first search (BFS) is one of the most fundamental processing algorithms in graph theory. We previously presented a scalable BFS algorithm based on Beamer's direction-optimizing algorithm for non-uniform memory access (NUMA)-based systems, in which the NUMA architecture was carefully considered. This paper presents our new implementation that reduces remote memory access in a top-down direction of direction-optimizing algorithm. We also discuss numerical results obtained on the SGI UV 2000 and UV 300 systems, which are shared-memory supercomputers based on a cache coherent (cc)-NUMA architecture that can handle thousands of threads on a single operating system. Our implementation has achieved performance rates of 219 billion edges per second on a Kronecker graph with 234 vertices and 238 edges on a rack of an SGI UV 300 system with 1,152 threads. This result exceeds the fastest entry for a shared-memory system on the current Graph500 list presented in November 2015, which includes our previous implementation.