Jose -

I noticed that your output doesn't appear to match what the source code is capable of generating. It's possible that you're running into problems with the code that we can't see because you didn't send a complete version of the source code.

You might want to start by running some 3rd party codes that are known to be good, just to make sure that your MPI installation checks out. A good start is NetPIPE, which runs between two peers and gives latency / bandwidth information. If that runs, then it's time to look at your application. If that doesn't run, then it's time to look at the MPI installation in more detail. In this case, it would be useful to see all of the information requested here:

  http://www.open-mpi.org/community/help/

as well as from running the mpirun command used to start NetPIPE with the -d option, so something like:

  mpirun -np 2 -hostfile foo -d ./NPMpi

Brian

On Feb 28, 2006, at 9:29 AM, 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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  Brian Barrett
  Open MPI developer
  http://www.open-mpi.org/


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