Thread-Count Tuning for Carbon-Efficient Multicore HPC Applications

  • Arthur Silveira UFRGS
  • Matheus Costa UFRGS
  • Carla Osthoff LNCC
  • Philippe O. A. Navaux UFRGS
  • Arthur Lorenzon UFRGS

Resumo


As multicore HPC systems expose increasingly large degrees of parallelism, using more hardware resources does not necessarily translate into more useful scientific computation. Once application scalability saturates, activating additional threads can provide little or no performance benefit while increasing energy consumption and the carbon cost of computation. Therefore, understanding this trade-off is essential for improving resource efficiency and advancing sustainable HPC. In this paper, we quantify how thread-count tuning affects performance and operational carbon emissions across 20 OpenMP applications and five multicore CPU platforms spanning 16–128 hardware threads. A full design-space exploration identifies performance-, carbon-, and joint-optimal configurations. Relative to maximum-thread execution, performance-optimal tuning improves geometric-mean runtime by up to 16.0%, while carbon-optimal tuning reduces emissions by up to 27.8%. Scalability-limited workloads benefit substantially more: sp.C reduces emissions by 69.5% on AMD128.

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Publicado
03/11/2026
SILVEIRA, Arthur; COSTA, Matheus; OSTHOFF, Carla; NAVAUX, Philippe O. A.; LORENZON, Arthur. Thread-Count Tuning for Carbon-Efficient Multicore HPC Applications. In: SIMPÓSIO EM SISTEMAS COMPUTACIONAIS DE ALTO DESEMPENHO (SSCAD), 27. , 2026, Natal/RN. Anais [...]. Porto Alegre: Sociedade Brasileira de Computação, 2026 . p. 192-205. DOI: https://doi.org/10.5753/sscad.2026.34906.