TurbSim: OpenMP parallelization in factorization and FFT #3020
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- Very cludgy mess. Seems to work locally though.
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The TRH_in in the SHARED was causing memory issues. Removing that makes things identical now.
No need for the inner loop.
…se THREADPRIVATE and COPYIN to create the necessary copies of TRH array in CalcFourierCoeffs_IEC instead of doing it manually
…hen not using OpenMP or explicitly setting the BLAS vendor. This should reduce the chances of slowdowns from calling the MKL with many small calculations trying to distribute it over many threads.
andrew-platt
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Nov 24, 2025
andrew-platt
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Nov 25, 2025
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@deslaughter's changes are great - a much better method than what I proposed.
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Needs some review and testing.
Feature or improvement description
TurbSim has been single-threaded forever. This PR adds parallelization through OpenMP and should in theory run faster as a result.
If OpenMP is enabled at compile time, parallelization for MKL will be automatically turned off. We saw this the MKL parallelization is an issue in #3018 when the MKL would try to parallelize some tiny matrix manipulation incurring massive overhead costs.
Still need to extend to the following routines:
CalcFourierCoeffs_APICalcFourierCoeffs_GeneralCalcFourierCoeffs_NoneRelated issue, if one exists
#3018
Impacted areas of the software
TurbSim only
Additional supporting information
APRIVATE(<allocatable_array>)in a!$OMP PARALLEL DOpragma doesn't always allocate the copy of that array. This leads to segfaults. I have messy workarounds for this. There may be a better way to do it, but I have no idea if the ROCM Flang compiler will be able to handle anything more advanced.THREADPRIVATEwithCOPYINworks better than the original solutionTest results, if applicable
No test results should change.