Your MPI_Recv is trying to receive from the slave(1), not the master (0).
Jose Pedro Garcia Mahedero wrote:
Hello everybody.
I'm new to MPI and I'm having some problems while runnig a simple
pingpong program in more than one node.
1.- I followed all the instructions and installed open MPI without
problems in a Beowulf cluster.
2.- Ths cluster is working OK and ssh keys are set for not password
prompting
3.- miexec seems to run OK.
4.- Now I'm using just 2 nodes: I've tried a simple ping-pong
application but my master only sends one request!!
5.- I reduced the problem by trying to send just two mesages to the same
node:
int main(int argc, char **argv){
int myrank;
/* Initialize MPI */
MPI_Init(&argc, &argv);
/* Find out my identity in the default communicator */
MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
if (myrank == 0) {
int work = 100;
int count=0;
for (int i =0; i < 10; i++){
cout << "MASTER IS SLEEPING..." << endl;
sleep(3);
cout << "MASTER AWAKE WILL SEND["<< count++ << "]:" << work << endl;
MPI_Send(&work, 1, MPI_INT, 1, WORKTAG, MPI_COMM_WORLD);
}
} else {
int count =0;
int work;
MPI_Status status;
while (true){
MPI_Recv(&work, 1, MPI_INT, 0, MPI_ANY_TAG, MPI_COMM_WORLD,
&status);
cout << "SLAVE[" << myrank << "] RECEIVED[" << count++ << "]:"
<< work <<endl;
if (status.MPI_TAG == DIETAG) {
break;
}
}// while
}
MPI_Finalize();
6a.- RESULTS (if I put more than one machine in my mpihostsfile), my
master sends the first message and my slave receives it perfectly. But
my master doesnt send its second .
message:
Here's my output
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[0]:100
MASTER IS SLEEPING...
SLAVE[1] RECEIVED[0]:100MPI_STATUS.MPI_ERROR:0
MASTER AWAKE WILL SEND[1]:100
6b.- RESULTS (if I put ONLY 1 machine in my mpihostsfile), everything
is OK until iteration 9!!!
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[0]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[1]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[2]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[3]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[4]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[5]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[6]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[7]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[8]:100
MASTER IS SLEEPING...
MASTER AWAKE WILL SEND[9]:100
SLAVE[1] RECEIVED[0]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[1]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[2]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[3]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[4]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[5]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[6]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[7]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[8]:100MPI_STATUS.MPI_ERROR:0
SLAVE[1] RECEIVED[9]:100MPI_STATUS.MPI_ERROR:0
--------------------------------
I know this is a lot of text, but I wanted to give a mamixum detailed
question. I've been search in FAQ, but still don't know what (and why)
is going on...
Anyone can help please :-) ?
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