[petsc-users] Scalability problem using PETSc with local installed OpenMPI

[Barry Smith]

  Take a look at https://petsc.org/release/faq/#what-kind-of-parallel-computers-or-clusters-are-needed-to-use-petsc-or-why-do-i-get-little-speedup

  Check the binding that OpenMPI is using (by the way, there are much more recent OpenMPI versions, I suggest using them). Run the STREAMS benchmark as indicated on that page.

  Barry


> On Oct 10, 2023, at 9:27 AM, Gong Yujie <yc17470 at connect.um.edu.mo> wrote:
> 
> Dear PETSc developers,
> 
> I installed OpenMPI3 first and then installed PETSc with that mpi. Currently, I'm facing a scalability issue, in detail, I tested that using OpenMPI to calculate an addition of two distributed arrays and I get a good scalability. The problem is when I calculate the addition of two vectors in PETSc, I don't have any scalability. For the same size of the problem, PETSc costs a lot much time than merely using OpenMPI. 
> 
> My PETSc version is 3.16.0 and the version of OpenMPI is 3.1.4. Hope you can give me some suggestions.
> 
> Best Regards,
> Yujie

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