Yes you're right. I forgot to mention that the OpenMP schedule used by the multi-threaded system was a static schedule as well (#pragma omp parallel schedule(static)) Rohan On Tue, Dec 14, 2021 at 3:26 PM Victor Eijkhout <[email protected]> wrote:

On , 2021Dec11, at 17:56, Rohan Yadav <[email protected]> wrote:

40 mpi ranks on a single node should be similar performance as 40 threads. Both petsc and taco are doing a row-based parallelism strategy so it should line up.

An MPI division of rows is static. Petsc divides strictly by numbers of rows.

A thread based system can do things like “schedule(guided)” (OpenMP) and get better load balancing if the rows have widely differing numbers of nonzero.

Victor.