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DTSTAMP:20260624T171340Z
LOCATION:Bldg. 8 - Entrance Hall
DTSTART;TZID=Europe/Stockholm:20260630T173000
DTEND;TZID=Europe/Stockholm:20260630T194500
UID:submissions.pasc-conference.org_PASC26_sess135_posC118@linklings.com
SUMMARY:ACMP07 - Mapping the Productivity-To-Energy Trade-Off in Memory-Bo
 und HPC via DVFS, Core Scaling, and C-State Control on Repurposed Hardware
DESCRIPTION:Suné Toerien (University of the Witwatersrand), Vele Nefale (U
 niverUniversity of the Witwatersrand), and Ntandoyenkosi Memela and Mubeen
  Dewan (University of the Witwatersrand)\n\nHigh-performance computing (HP
 C) systems in resource-constrained environments, such as Africa, often rel
 y on repurposed hardware, shifting the primary financial burden from capit
 al expenditure to operational energy costs. This work aims to identify rea
 listic and reproducible performance–energy sweet spots, providing practica
 l guidance for cost-efficient HPC operation by balancing modest reductions
  in performance with substantial energy savings. In this context, Producti
 vity-to-Energy (PTE) provides a more meaningful metric than raw performanc
 e alone for evaluating system efficiency and operational value. While Dyna
 mic Voltage and Frequency Scaling (DVFS) is a well-known energy-optimisati
 on tool, the combined effects of DVFS, core scaling, and deep CPU C-states
  remain poorly explored on repurposed HPC infrastructure. This project inv
 estigates these interactions for memory-bound HPC workloads on repurposed 
 hardware. Guided by recent findings (PEARC25) and the Knights Landing (KNL
 ) architecture, CPU configurations are adjusted on repurposed hardware to 
 better align with memory throughput and reduce latency. Extensive benchmar
 ks are conducted systematically varying CPU frequency and core-count confi
 gurations, with unused cores explicitly power-gated using deep C-states (C
 10) to ensure controlled hardware activation. Using real scientific worklo
 ads, such as HPCG, OpenFOAM, and Calculix, this research captures memory- 
 and latency-dominated behaviours to define energy-aware operating points r
 elevant for the African HPC community.\n\n
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