Early Experience on the Blue Gene/Q Supercomputing System

The Argonne Leadership Computing Facility (ALCF) is home to Mira, a 10 PF Blue Gene/Q (BG/Q) system. The BG/Q system is the third generation in Blue Gene architecture from IBM and like its predecessors combines system-onchip technology with a proprietary interconnect (5-D torus). Each compute node has 16 augmented PowerPC A2 processor cores with support for simultaneous multithreading, 4-wide double precision SIMD, and different data prefetching mechanisms. Mira offers several new opportunities for tuning and scaling scientific applications. This paper discusses our early experience with a subset of micro-benchmarks, MPI benchmarks, and a variety of science and engineering applications running at ALCF. Both performance and power are studied and results on BG/Q is compared with its predecessor BG/P. Several lessons gleaned from tuning applications on the BG/Q architecture for better performance and scalability are shared.