Re: [Starpu-devel] Processor grid and data distribution

[Samuel Thibault <samuel.thibault@inria.fr>]

Hello,

Hatem Ltaief, le jeu. 18 oct. 2018 09:43:08 +0000, a ecrit:
> Is there a way to specify an arbitrary processor grid and data distribution 
> in an MPI-based application? How?
> In fact, are the data structure and the way it is distributed via processor 
> grid completely uncoupled?

I'm not sure what you mean by processor grid.

The way it is usually done is to set for each data the MPI node it
resides on with starpu_mpi_data_register or starpu_mpi_data_set_rank.
By default each task gets executed on the node which owns
the data which is written to by the task.  One can use
starpu_mpi_node_selection_register_policy to set this to another policy,
or use STARPU_EXECUTE_ON_NODE to explicitly specify the node which shall
execute the task. The data location and the task execution location are
thus completely uncoupled.

Samuel