In FEM applications, each processor needs only data from neighboring processors, which gives a stencil or star pattern of communication. In MPI_Win for MPI_Get, one needs to setup a group of processors to window on common data.  But what we usually need is specifying a stencil pattern for MPI_Get. And it seems to me MPI_Win is a lot of waste, isn't it?  Maybe there is a related question.
Is there MPI_Star instead of MPI_Win (window) for MPI_Get?
finite element;parallel computing;petsc;mpi