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Tech Talk: Debugging with DDT

This talk will provide an introduction to the use of DDT for debugging parallel applications on the mistral supercomputer.
Mar 16, 2021 from 03:15 PM to 04:15 PM (Europe/Berlin / UTC100)
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Debugging parallel climate models can be a daunting task, but it becomes much easier once you can study the state of all model variables at the moment of the crash, or any other unexpected behavior. On Mistral, ARM DDT provides a user-friendly GUI for debugging simulations with up to 1000 MPI threads, and on Levante, we will keep providing DDT. In this Tech Talk, Suyash Sharma of ARM will introduce the basic concepts of using a debugger and demonstrate how DDT can provide insights into a real-world ICON crash.

Please find the talk at

Find more info on DDT on mistral at

Q & A :


  • Can DDT detect OpenMP data race conditions in shared memory parallel code?

    • look into -fsanitize=thread
      - contact us at [Email protection active, please enable JavaScript.] if you need further help.
  • Can DDT unwind the stack on GPU accelerated code?

    • yes.

  • Can ddt now handle MPMD setups?

  • Have you already worked with code from externals? (e.g. JSBACH4)
    • They are part of the executable. There should be no difference.

  • Can ddt handle also code with more than one executable?
    • Yes, that’s MPMD.


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