int main(int argc, char *argv[])
{
- const int tag1 = 42, tag2= 43; /* Message tag */
- int rank;
- int size;
- int msg=99;
- int err;
- int pivot;
- MPI_Status status;
+ const int tag1 = 42, tag2 = 43; /* Message tag */
+ int rank;
+ int size;
+ int msg = 99;
+ int err;
+ int pivot;
+ MPI_Status status;
- err = MPI_Init(&argc, &argv); /* Initialize MPI */
- if (err != MPI_SUCCESS) {
- printf("MPI initialization failed!\n");
- exit(1);
- }
- err = MPI_Comm_size(MPI_COMM_WORLD, &size); /* Get nr of tasks */
- err = MPI_Comm_rank(MPI_COMM_WORLD, &rank); /* Get id of this process */
- if ( size < 2 ) {
- printf("run this program with exactly 2 processes (-np 2)\n");
- MPI_Finalize();
- exit(0);
- }
- if (0 == rank) {
- printf("\n *** Ping-pong test (MPI_Send/MPI_Recv) ***\n\n");
- }
+ err = MPI_Init(&argc, &argv); /* Initialize MPI */
+ if (err != MPI_SUCCESS) {
+ printf("MPI initialization failed!\n");
+ exit(1);
+ }
+ err = MPI_Comm_size(MPI_COMM_WORLD, &size); /* Get nr of tasks */
+ err = MPI_Comm_rank(MPI_COMM_WORLD, &rank); /* Get id of this process */
+ if (size < 2) {
+ printf("run this program with exactly 2 processes (-np 2)\n");
+ MPI_Finalize();
+ exit(0);
+ }
+ if (0 == rank) {
+ printf("\n *** Ping-pong test (MPI_Send/MPI_Recv) ***\n\n");
+ }
- /* start pingpong tests between several pairs */
- for (pivot=0; pivot<size-1; pivot++) {
+ /* start pingpong tests between several pairs */
+ for (pivot = 0; pivot < size - 1; pivot++) {
- if (pivot == rank) {
- printf("\n== pivot=%d : pingpong [%d] <--> [%d]\n",pivot,pivot,pivot+1);
+ if (pivot == rank) {
+ printf("\n== pivot=%d : pingpong [%d] <--> [%d]\n", pivot, pivot,
+ pivot + 1);
- int dst= rank + 1;
- printf("[%d] About to send 1st message '%d' to process [%d] \n", rank,msg, dst);
- err = MPI_Send(&msg, 1, MPI_INT, dst, tag1, MPI_COMM_WORLD);
+ int dst = rank + 1;
+ printf("[%d] About to send 1st message '%d' to process [%d] \n",
+ rank, msg, dst);
+ err = MPI_Send(&msg, 1, MPI_INT, dst, tag1, MPI_COMM_WORLD);
- err = MPI_Recv(&msg, 1, MPI_INT, dst, tag2, MPI_COMM_WORLD, &status); /* Receive a message */
- printf("[%d] Received relpy message '%d' from process [%d] \n", rank,msg, dst);
+ err = MPI_Recv(&msg, 1, MPI_INT, dst, tag2, MPI_COMM_WORLD, &status); /* Receive a message */
+ printf("[%d] Received relpy message '%d' from process [%d] \n", rank,
+ msg, dst);
- }
- if ((pivot+1) == rank) {
- int src= rank - 1;
- err = MPI_Recv(&msg, 1, MPI_INT, src, tag1, MPI_COMM_WORLD, &status); /* Receive a message */
- printf("[%d] Received 1st message '%d' from process [%d] \n", rank,msg, src);
- msg++;
- printf("[%d] increment message's value to '%d'\n", rank,msg);
- printf("[%d] About to send back message '%d' to process [%d] \n", rank,msg, src);
- err = MPI_Send(&msg, 1, MPI_INT, src, tag2, MPI_COMM_WORLD);
- }
- }
- err = MPI_Finalize(); /* Terminate MPI */
- return 0;
+ }
+ if ((pivot + 1) == rank) {
+ int src = rank - 1;
+ err = MPI_Recv(&msg, 1, MPI_INT, src, tag1, MPI_COMM_WORLD, &status); /* Receive a message */
+ printf("[%d] Received 1st message '%d' from process [%d] \n", rank,
+ msg, src);
+ msg++;
+ printf("[%d] increment message's value to '%d'\n", rank, msg);
+ printf("[%d] About to send back message '%d' to process [%d] \n",
+ rank, msg, src);
+ err = MPI_Send(&msg, 1, MPI_INT, src, tag2, MPI_COMM_WORLD);
+ }
+ }
+ err = MPI_Finalize(); /* Terminate MPI */
+ return 0;
}
