Conference Presentation (After Call) FZJ-2026-04464

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NUMA balancing hampering performance of spiking network simulations



2026

International Conference on Neuromorphic Computing, ICNCE 2026, AachenAachen, Germany, 28 Jun 2026 - 2 Jul 20262026-06-282026-07-02

Abstract: Computing centers today mostly operate conventional CPU- and GPU-based systems, where thedirect way of reducing energy consumption is a reduction in the applications’ runtime. Neuromor-phic computing promises energy efficient architectures for artificial intelligence. In this endeavor,code for the simulation of large-scale spiking networks on conventional supercomputers is the ref-erence. We show that turning off automatic NUMA balancing may reduce energy consumption by20%. This dwarfs other attempts of cost-effective efficiency measures of a computing center. Thememory access pattern of spiking network simulation code dynamically interacts with automaticNUMA balancing. This does not affect the correctness of simulation results and thus goes unno-ticed in day-to-day neuroscience research. In performance analysis, however, time measurementsfluctuate, obstructing attempts to optimize simulation technology. A new time- and compute-noderesolved performance display exposes fine-grained temporal variability during distributed spikingnetwork simulations. The analysis shows that automatic NUMA balancing is disadvantageous, partic-ularly affecting the jemalloc library for thread-aware memory allocation in a transient manner. Thenew method also allows developers to detect perturbations of HPC systems and target improvementsto simulation technology. As a consequence, we have equipped our supercomputer JURECA with anoption to turn on or off automatic NUMA balancing per-node at user level. This gives researchers theopportunity to optimize settings for their applications. There are indications in the literature that theeffect has been observed before, yet it does not seem common knowledge in scientific computing. Itremains to be investigated how widespread the phenomenon is among scientific codes.


Contributing Institute(s):
  1. Computational and Systems Neuroscience (IAS-6)
Research Program(s):
  1. 5231 - Neuroscientific Foundations (POF4-523) (POF4-523)
  2. 5232 - Computational Principles (POF4-523) (POF4-523)
  3. BMFTR 03ZU2106CB - NeuroSys: Algorithm-Hardware Co-Design (Projekt C) - B (03ZU2106CB) (03ZU2106CB)
  4. EBRAINS 2.0 - EBRAINS 2.0: A Research Infrastructure to Advance Neuroscience and Brain Health (101147319) (101147319)
  5. JL SMHB - Joint Lab Supercomputing and Modeling for the Human Brain (JL SMHB-2021-2027) (JL SMHB-2021-2027)
  6. GRK 2416 - GRK 2416: MultiSenses-MultiScales: Neue Ansätze zur Aufklärung neuronaler multisensorischer Integration (368482240) (368482240)
  7. DFG project G:(GEPRIS)545776403 - FOR 5880: Ganzheitliche Energie- und Leistungsmodellierung für nachhaltiges Rechnen (Mod4Comp) (545776403) (545776403)
  8. HiRSE - Helmholtz Platform for Research Software Engineering (HiRSE-20250220) (HiRSE-20250220)

Appears in the scientific report 2026
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 Record created 2026-09-17, last modified 2026-09-23



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