MPI struct ring program

Question

Can you help me solve the advanced version of this question

• A set of processes are arranged in a ring.

• Each process stores its rank in MPI_COMM_WORLD into an integer variable snd_buf.

• Each process passes this on to its neighbor on the right.

• Each processor calculates the sum of all values.

• Keep passing it around the ring until the value is back where it started, i.e.

• each process calculates sum of all ranks.

• Use non-blocking MPI_Issend

  – to avoid deadlocks

  – to verify the correctness, because blocking synchronous send will cause a deadlock

here is my program

#include <stdio.h>
#include <mpi.h>

int main(int argc, char** argv) {
    MPI_Init(&argc, &argv);

    int rank, size;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    int snd_buf = rank;
    int rcv_buf;
    int total_sum = 0;

    MPI_Request send_request, recv_request;
    MPI_Status recv_status;

    // Start the non-blocking send
    MPI_Issend(&snd_buf, 1, MPI_INT, (rank + 1) % size, 0, MPI_COMM_WORLD, &send_request);

    do {
        MPI_Recv(&rcv_buf, 1, MPI_INT, (rank - 1 + size) % size, 0, MPI_COMM_WORLD, &recv_status);

        total_sum += rcv_buf;

        // Wait for the non-blocking send
        MPI_Wait(&send_request, MPI_STATUS_IGNORE);
        
        MPI_Issend(&rcv_buf, 1, MPI_INT, (rank + 1) % size, 0, MPI_COMM_WORLD, &send_request);
    } while (rcv_buf != rank);

    printf("Rank %d: Total Sum of Ranks = %d\n", rank, total_sum);

    MPI_Finalize();

    return 0;
}

I need help with the advanced version of it which is the following

• Modify the pass-around-the-ring exercise.

• Calculate two separate sums:

  • –  rank integer sum (as before)

  • –  rank floating point sum

• Use a struct datatype for this

• with same fixed memory layout for send and receive buffer.

• use int MPI_Type_struct(int count, int \*array_of_blocklengths, MPI_Aint \*array_of_displacements, MPI_Datatype \*array_of_types, MPI_Datatype \*newtype)

i am trying to use int MPI_Type_struct(int count, int \*array_of_blocklengths, MPI_Aint \*array_of_displacements, MPI_Datatype \*array_of_types, MPI_Datatype \*newtype)

but so far can not reach any results :(