Reply To: Issues with Lumerical Initialization, Linux Processes and FDTD efficient usage

[Lito]

Hi Naveen,

(1) If the simulation is stuck at the initialization stage, please try to remove the Lumerical Product Preference.ini files from your user's folder on your system. See KB: <<Ansys Lumerical product preference files – Ansys Optics>>

(2) On Linux, we do not bundle anymore the MPI package starting with the 2024 releases. To run on multiple MPI processes, this will require the MPI package on Linux e.g. OpenMPI or IntelMPI.  See this KB for details: <<Running simulations with MPI on Linux – Ansys Optics>>. Otherwise, without MPI, you can only run with "Local Computer" as the "Job launching preset", and can only set the number of threads up to the number of threads/logical processors on the system. The processes field will be disable since this is only for MPI. <<Resource configuration elements and controls – Ansys Optics>>. The capacity is only used running concurrent parametric sweeps. <<Concurrent Parametric Computing – Ansys Optics>> 

(3) Typically we run 1 MPI process on 1 CPU core/logical processor/thread - depending if the system has hyperthreading enabled.

• You can set the [processes x threads x capacity] up to a maximum number of cores or logical processors/threads on your machine.  
• Try different combinations as long as the product of the 3 settings does not go over 32 threads. e.g. (16x2x1), (32x1x1), (4x8x1), (2x16x1), (1x32x1)
• Using only the 24 physical cores, e.g. (24x1x1), (12x2x1), (6x4x1), (1x24x1), (2x12x1)

You will have to run with different combinations to get the optimum resource configuration for your simulation on a machine/system. This will vary depending on your simulation/model. You will have to check the 'simulation_p0.log' file for the FDTD solver speed for each resource configuration. <<Determining the optimum resources to run FDTD – Ansys Optics>>