--- /dev/null
+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define N (1024 * 1024 * 1)
+
+int main(int argc, char* argv[])
+{
+ int size, rank;
+ struct timeval start, end;
+ char hostname[256];
+ int hostname_len;
+
+ MPI_Init(&argc, &argv);
+
+ MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+ MPI_Comm_size(MPI_COMM_WORLD, &size);
+ MPI_Get_processor_name(hostname, &hostname_len);
+
+ // Allocate a 1 MiB buffer
+ char* buffer = malloc(sizeof(char) * N);
+
+ // Communicate along the ring
+ if (rank == 0) {
+ gettimeofday(&start, NULL);
+ printf("Rank %d (running on '%s'): sending the message rank %d\n", rank, hostname, 1);
+ MPI_Send(buffer, N, MPI_BYTE, 1, 1, MPI_COMM_WORLD);
+ MPI_Recv(buffer, N, MPI_BYTE, size - 1, 1, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+ printf("Rank %d (running on '%s'): received the message from rank %d\n", rank, hostname, size - 1);
+ gettimeofday(&end, NULL);
+ printf("%f\n", (end.tv_sec * 1000000.0 + end.tv_usec - start.tv_sec * 1000000.0 - start.tv_usec) / 1000000.0);
+
+ } else {
+ MPI_Recv(buffer, N, MPI_BYTE, rank - 1, 1, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
+ printf("Rank %d (running on '%s'): receive the message and sending it to rank %d\n", rank, hostname,
+ (rank + 1) % size);
+ MPI_Send(buffer, N, MPI_BYTE, (rank + 1) % size, 1, MPI_COMM_WORLD);
+ }
+
+ MPI_Finalize();
+ return 0;
+}