C99 fixed-width integer types are your friend.
https://www.mpi-forum.org/docs/mpi-2.2/mpi22-report/node44.htm
Jeff
On Wed, Mar 13, 2019 at 3:12 PM Sergio None <sgzbrowi...@hotmail.com> wrote:
> Hello.
>
> I'm using OpenMPI 3.1.3 on x64 CPU and two ARMv8( Raspberry pi 3).
>
> But i'm having some issues with data types that are architecture
> dependent, like 'long'.
>
> For example, if you send data in one process to other on this way:
>
> if (my_rank != 0) {
> long size;
> char* array_data;
>
> array_data = malloc(size);
> //Initialize data...
>
> /* Send size first*/
> MPI_Ssend(&size, 1, MPI_LONG, 0, 0, MPI_COMM_WORLD);
>
> /* Send data*/
> MPI_Ssend(array_data, size, MPI_BYTE, 0, 0, MPI_COMM_WORLD);
>
> }else{
> char* data_of_procs[num_procs-1];
> long size_data_procs[num_procs-1];
> int i;
> for(i=0;i<num_procs-1;i++){
> /* Receive size*/
> MPI_Recv(&size_data_procs[i], 1, MPI_LONG, i+1, 0, MPI_COMM_WORLD,
> &status);
> data_of_procs[i] = malloc(size_data_procs[i]);
> if (data_of_procs[i] == NULL) perror("Error on malloc");
> MPI_Recv(data_of_procs[i], size_data_procs[i], MPI_BYTE, i+1, 0,
> MPI_COMM_WORLD, &status);
> }
> }
>
> Probably you get an error of malloc saying to you: "can't allocate this
> memory". This fail because long in x86 are 8bytes and in arm compiler is
> 4bytes. For solve, instead of use long, you need to use int that have the
> same size in both architectures. Other option could be serialize long.
>
> So my question is: there any way to pass data that don't depend of
> architecture?
>
>
>
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--
Jeff Hammond
jeff.scie...@gmail.com
http://jeffhammond.github.io/
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