Yes! Indeed, the second is the efficient way to store my 2D-slice.
So, following option 2:
1- I’ve grouped the processors with coord(3).EQ.1 from original_group:
MPI_COMM_GROUP(MPI_COMM_WORLD, original_group)
MPI_GROUP_INCL(original_group, nb_process_2D_SLICE, processes_2D_SLICE,
2D_group,code)
2- I’ve created a MPI communicator for this group:
MPI_COMM_CREAT(MPI_COMM_WORLD, my_group_2D, MPI_COMM_2D_SLICE, code)
—Problem—
When I do:
CALL MPI_COMM_RANK(MPI_COMM_2D_SLICE, 2D_ranks, code)
I’ve a segmentation fault… Did you have this problem?
—After solving this problem —
3 - You say that instead of MPI_COMM_WORLD I shall use MPI_COMM_2D_SLICE here?:
comm = MPI_COMM_2D_SLICE
h5pset_fapl_mpio_f(plist_id, comm, info)
Thank you a lot!
It was very helpful
Cheers,
Maria
On 10 Mar 2015, at 14:38, Angel de Vicente <[email protected]> wrote:
> Hi Maria,
>
> Maria Castela <[email protected]> writes:
>
>> Dear all,
>> When I use
>> CALL h5pcreate_f(H5P_FILE_ACCESS_F, plist_id, error)
>> CALL h5pset_fapl_mpio_f(plist_id, comm, info, error)
>> I assume that all processors are called to write the solution.
>> However, I just want the processors which have coords(3) equals a certain
>> value to write the solution… (constant z plane)
>> Figure below shows an example of what I want and what the program is doing.
>> How do I impose this condition? I have already tried
>> « IF (coord(3) == 1) THEN
>> CALL h5pcreate_f(H5P_FILE_ACCESS_F, plist_id, error)
>> etc…
>> ENDIF «
>> However It doesn’t like it.
>
> We do need this in our code as well, and we have two different ways of
> doing it:
>
> 1) if all processors are going to take part in the I/O operation, then
> when you define the amount of data each processor is contributing,
> this will be 0 for all processors except those with coord(3) .EQ. 1
> then all processors do exactly the same collective operations, except
> that the amount of data they read/write will be different.
>
> 2) you create a MPI communicator that groups those processors where
> coord(3) .EQ. 1. Then, only those processors will contribute to the
> I/O operation, which is similar to what your post seems to imply you
> want to do, but then you have to make sure that the communicator in
> your calls is not the global one (MPI_COMM_WORLD), but rather the one
> you created specifially for coord(3) .EQ. 1
>
> If this doesn't lead you very far, I can give you further details.
>
> Cheers,
> --
> Ángel de Vicente
> http://www.iac.es/galeria/angelv/
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