[Mpi3-ft] New version of the RTS proposal

[Darius Buntinas]

In MPI_Cart_sub, processes don't "contribute" to the operation, so the current sentence on p561 doesn't really make sense.  However, I don't think what we did for MPI_Comm_split will work here either.  I think that MPI_Cart_sub should create the communicators as described in Section 7.5.7, which may result in failed processes being included in a new communicator.

E.g., in Example 7.8 on p291, if the process at coordinate (0,2,1) in the topology failed, then if remain_dims = (true, false, true), then the third communicator (i.e., the one containing processes at coordinates (A,2,B), A = 0..1, B = 0..3) would have a failed process (at coordinates (0,1) ).

Maybe the example makes things more confusing.  I think MPI_CART_SUB is already covered in by the sentence starting on line 7 page 561, so we can probably take the MPI_CART_SUB sentence out.

-d


On Nov 7, 2011, at 12:58 PM, Josh Hursey wrote:

> * I would like some more folks to look over the process topologies
> chapter. In particular I think we need to fix the wording for
> MPI_CART_SUB - maybe to better match the wording for mpi_comm_split.