HaloPencils

A micro-package for adding halo-cell functionality to PencilArrays.jl

Halo updates are performed using the Irecv and Isend MPI commands, following the Fortran implementation of the 2decomp-fft library.

The only object in the package thus far is a halo update function update_halo! that treats the local edges of a PencilArray as a halo that needs to be shared with neighbouring processes.

Future development ideas

• A HaloPencil type that wraps a Pencil, but also takes in and stores details of the periodicity and the halo size.
  • localgrid() functions for a HaloPencil that account for the overlap of successive processes due to the presence of a halo.
• A HaloPencilArray type wrapping a PencilArray that uses a HaloPencil
  • global_view function that accounts for the halo overlap when indexing (perhaps with an OffsetArray even for rank 0 process starting at 1-lvlhalo)