Abstract
Emergence of new parallel architectures presents new challenges for
application developers. Supercomputers vary in processor speed,
network topology, interconnect communication characteristics and
memory subsystems. This paper presents a performance comparison of
three of the fastest machines in the world: IBM's Blue Gene/P
installation at ANL (Intrepid), the SUN-Infiniband cluster at TACC
(Ranger) and Cray's XT4 installation at ORNL (Jaguar). Comparisons
are based on three applications selected by NSF for the Track 1
proposal to benchmark the Blue Waters system: NAMD, MILC and a
turbulence code, DNS. We present a comprehensive overview of the
architectural details of each of these machines and a comparison of
their basic performance parameters. Application performance is
presented for multiple problem sizes and the relative performance
on the selected machines is explained through micro-benchmarking
results. We hope that insights from this work will be useful to
managers making buying decisions for supercomputers and application
users trying to decide on a machine to run on. Based on the
performance analysis techniques used in the paper, we also suggest
a step-by-step procedure for estimating the suitability of a given
architecture for a highly parallel application.