ModSIm ass4: Created a basic ring program.

modsim/ass4_taddeus/ring.c

@@ -2,10 +2,45 @@
 #include <stdio.h>
 #include <mpi.h>
 
+double *data = {.0};
+
+void initialize_ring(void) {
+    double received;
+
+    puts("Sending first data");
+    MPI_Send(data, 1, MPI_DOUBLE, 2, MPI_ANY_TAG, MPI_COMM_WORLD);
+    MPI_Recv(&received, 1, MPI_DOUBLE, tasks - 1, MPI_ANY_TAG, MPI_COMM_WORLD);
+
+    if( received != *data )
+        printf("Received data does not match (sent: %f, received: %f)\n",
+                *data, received);
+    else
+        puts("Data received succesfully");
+}
+
+void pass_data(int tasks, int rank) {
+    double received;
+
+    printf("Task %d sending data\n", task);
+    MPI_Recv(&received, 1, MPI_DOUBLE, (rank - 1 + tasks) % tasks, MPI_ANY_TAG, MPI_COMM_WORLD);
+    MPI_Send(data, 1, MPI_DOUBLE, (rank + 1) % tasks, MPI_ANY_TAG, MPI_COMM_WORLD);
+}
+
 int main(int argc, char **argv) {
-    MPI_Init(&argc, &argv);
+    int tasks, rank, error;
+
+    if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
+        printf("MPI_init failed (error %d)\n", error);
+        MPI_Abort(MPI_COMM_WORLD, error);
+    }
 
+    MPI_Comm_size(MPI_COMM_WORLD, &tasks);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 
+    if( !rank )
+        initialize_ring();
+    else
+        pass_data(tasks, rank);
 
     MPI_Finalize();
 }

modsim/ass4_taddeus/ring.sh

@@ -4,5 +4,6 @@ RSH_AGENT=rsh
 MPI_HOSTFILE=~/.mpirun.machines
 PROGRAM_EXEC=ring
 
-mpirun -np $NUM_PROCESSES --mca pls_rsh_agent $RSH_AGENT \
-    --hostfile $MPI_HOSTFILE $PROGRAM_EXEC
+mpirun -np $NUM_PROCESSES $PROGRAM_EXEC
+#mpirun -np $NUM_PROCESSES --mca pls_rsh_agent $RSH_AGENT \
+#    --hostfile $MPI_HOSTFILE $PROGRAM_EXEC