I'm trying to understand how VecScatters work with GPU-native Kokkos Vecs.
Specifically, I'm interested in what will happen in code like in
src/vec/vec/tests/ex22.c,
ierr = VecScatterCreate(x,is1,y,is2,&ctx);CHKERRQ(ierr);
(from https://gitlab.com/petsc/petsc/-/blob/master/src/vec/vec/tests/ex22.c#L44
<https://gitlab.com/petsc/petsc/-/blob/master/src/vec/vec/tests/ex22.c#L44>)
Here, x and y can be set to type KOKKOS using -vec_type kokkos at the command
line. But is1 and is2 are (I think), always
CPU/host data. Assuming that the scatter itself can happen on the GPU, the
indices must make it to the device somehow - are they copied there when the
scatter is created? Is there a way to create the scatter using indices already
on the GPU (Maybe using SF more directly)?
