TibidaboI: Making the Case for an ARM-Based HPC System Nikola Rajovica,b,∗, Alejandro Ricoa,b, Nikola Puzovica, Chris Adeniyi-Jonesc, Alex Ramireza,b aComputer Sciences Department, Barcelona Supercomputing Center, Barcelona, Spain bDepartment d'Arquitectura de Computadors, Universitat Polit`ecnica de Catalunya - BarcelonaTech, Barcelona, Spain cARM Ltd., Cambridge, United Kingdom Abstract It is widely accepted that future HPC systems will be limited by their power consumption. Current HPC systems are built from commodity server pro- cessors, designed over years to achieve maximum performance, with energy efficiency being an after-thought. In this paper we advocate a different ap- proach: building HPC systems from low-power embedded and mobile tech- nology parts, over time designed for maximum energy efficiency, which now show promise for competitive performance. We introduce the architecture of Tibidabo, the first large-scale HPC clus- ter built from ARM multicore chips, and a detailed performance and energy efficiency evaluation. We present the lessons learned for the design and im- provement in energy efficiency of future HPC systems based on such low- power cores. Based on our experience with the prototype, we perform simu- lations to show that a theoretical cluster of 16-core ARM Cortex-A15 chips would increase the energy efficiency of our cluster by 8.7x, reaching an energy efficiency of 1046 MFLOPS/W. Keywords: high-performance computing, embedded processors, mobile ITibidabo is a mountain overlooking Barcelona ∗Corresponding author Email addresses:
[email protected] (Nikola Rajovic),
[email protected] (Alejandro Rico),
[email protected] (Nikola Puzovic),
[email protected] (Chris Adeniyi-Jones),
[email protected] (Alex Ramirez) Preprint of the article accepted for publication in Future Generation Computer Systems, Elsevier processors, low power, cortex-a9, cortex-a15, energy efficiency 1.