Tpetra::Map::isCompatible could use Directory to avoid all-reduce if Map is contiguous
Created by: mhoemmen
@trilinos/tpetra
Tpetra::Map::isCompatible currently requires an all-reduce for contiguous but nonuniform Maps (that is, Maps created by the Map constructor that takes a global and a local number of indices):
If the Map has a Directory already, then the Directory has that information already, stored redundantly on each process. Note that it's not worth creating the Directory if it doesn't already exist, because doing so costs an MPI scan.