A Center for Sustainable Cloud Computing

The 2019 Spring Simulation Conference (SpringSim’19) concluded on May 2 at Tucson, Arizona. During the four-day event, many original papers were presented on the theory and practice of modeling and simulation in the scientific and engineering fields. The conference was especially significant for EPFL and EcoCloud because a paper co-authored by PhD scholar Yasir Mahmood Qureshi was selected for the “Runner-up Paper Award.”

In developing the paper “Gem5-X: A Gem5-Based System Level Simulation Framework to Optimize Many-Core Platforms,” Yasir Qureshi worked closely with co-authors William Andrew Simon, Marina Zapater, David Atienza (all from EPFL), and Katzalin Olcoz (Complutense University of Madrid). Addressing the two fundamental limitations of online services—power and latency—the paper presents gem5-X, a gem5-based system level simulation framework to optimize many-core systems. Gem5-X is a full-system simulation of ARM-64 in-order and Out-of-Order architectures running on a modern Linux OS.

The study showed that gem5-X can be used to identify bottlenecks and evaluate the potential benefits of architectural extensions such as in-cache computing and 3D stacked High Bandwidth Memory. Using case studies of real-time video transcoding and image classification with convolutional neural networks (CNNs), the researchers were able to achieve significant improvements in performance efficiency. They recorded a 15% speed-up using in-order cores with in-cache computing when compared to a baseline in-order system and 76% energy savings when compared to an Out-of-Order system. With HBM, acceleration of real-time transcoding and CNNs were up by 7% and 8% respectively.

The gem5-X simulation framework could emerge as a major enabler for computer architects because it is open-sourced with a technical whitepaper. It offers fast simulation of many-core ARM 64-bit architectures with innovative architectural extensions. It is available at esl.epfl.ch/gem5-x

The eminent selection committee at SpringSim’19 selected the paper for the Runner-up Paper Award because it makes a major contribution to the state-of-the-art in modeling and simulation. The award highlights the work being done by EcoCloud and EPFL researchers on new open-source architectural simulation frameworks for ARM and RISC-V many-core systems.