On Tue, Oct 10, 2023 at 9:28 AM Gong Yujie <yc17...@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. > 1. For any performance question, we really need to see the output of -log_view for each run. 2. I am not sure I understand your question. Vector addition does not involve communication. Thus it will scale perfectly in the absence of load imbalance. Thanks, Matt > Best Regards, > Yujie > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>