2nd CROCO Webinar: Friday, April 10th - A Walkthrough of CROCO on GPUs

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Dear colleagues,

We are pleased to announce the second webinar dedicated to the CROCO (Coastal and Regional Ocean COmmunity) model.

As a reminder, the goal of this initiative is to provide thematic talks about specific modules (e.g., MUSTANG for sediment, biogeochemistry models available) or key features (e.g., non-hydrostatic capabilities with NBQ, nesting with AGRIF, or output handling with XIOS). The philosophy of these talks is not only to highlight CROCO’s capabilities but also to openly discuss current limitations and constraints. Please note that the technical prerequisites required to follow the talks may vary from session to session.

We aim to schedule 4 to 5 sessions per year (roughly one every two to three months). To keep the format concise and interactive, each session will have a total duration of approximately 45 minutes, including 10 to 20 minutes dedicated to questions and answers.

Second session: A Walkthrough of CROCO on GPUs

Date: Friday, April 10th, 2026 Time: 13:30 (Paris time, UTC+2).

  • Hardware & Setup: A guide to the necessary GPU architectures, the essential development toolkit (NVHPC, OpenACC), and current implementation limits.

  • Practical Insights: A step-by-step guide on how to launch and manage simulations on GPUs.

  • Performance & Gains: What to realistically expect and which configurations GPUs handle best.

  • Problem Solving: A practical look at common runtime hurdles, including tips and “recipes” to resolve them.

  • Development Tools: Key utilities for profiling and optimizing your code for accelerated oceanic simulations.

  • Future Horizons: An overview of upcoming model improvements and the long-term roadmap for GPU integration.

Attend the webinar live at the link below, or watch the recording later on the croco website or our YouTube channel.

Link:https://webinaire.numerique.gouv.fr/meeting/signin/invite/70101/creator/40806/hash/376df9556e1f29c32b7fd2132053210820a36a4a

Provisional Schedule:

We have currently planned the following sessions for the coming months (subject to minor adjustments), and you can follow the latest updates on the following page: https://www.croco-ocean.org/user-meetings/ :

  • June 12th: Python post-processing tools for CROCO

  • Seminar - date to be confirmed in autumn, approximately one week after the CROCO release: presentation of the content, improvements

We look forward to seeing many of you there.

Best regards,

The CROCO Development Team

1 Like
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Hi, thank you for a very interesting webinar. I asked this follow up question on a separate thread but since I didn’t get any answer, I will ask again here in case you see it:

Is it possible to run CROCO on GPU with FP32 (single precision) selected? How can we select FP32 over FP64?

Thanks

Konstantinos

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HI,

FP32,FP64 : You can change at compilation time in jobcomp options (-fdefault-real-8 -fdefault-double-8, or i4 -r8, …). But.
Currently, CROCO’s GPU implementation is designed for Double Precision (FP64). While switching to FP32 would theoretically increase throughput on workstation cards, it raises significant concerns regarding numerical stability. In ocean modeling, the loss of precision often requires a drastic reduction of the time step dt to maintain stability and conservation properties. This could potentially negate any performance gains achieved by the faster FP32 compute. A thorough study on numerical convergence would be necessary before implementing this as a standard option. So to test !
Thanks
Cyril

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Hi,
This slash need to remove in FP64 case?
master/OCEAN/copy_to_host_xios_diag.h#L476

!$acc& , /rho_nbq_avg1

copyin-copyout (one extra pmask need to remove currently?)
master/OCEAN/copy_to_devices.F#L57
master/OCEAN/copy_to_devices.F#L177

Thank you.

Best regards