[petsc-dev] MPI derived datatype use in PETSc

[Victor Eijkhout]

The Ohio mvapich people are working on getting better performance out of MPI datatypes. I notice that there are 5 million lines in the petsc source that reference MPI datatypes. So just as a wild guess:

Optimizations on MPI Datatypes seem to be beneficial mostly if you’re sending blocks of at least a kilobyte each. Is that a plausible usage scenario? What is the typical use of MPI Datatypes in PETSc, and what type of datatype would most benefit from optimization?

Victor.