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Subject: [OMPI users] wrong rank and process number
From: Victor Rosas Garcia (rosas.victor_at_[hidden])
Date: 2009-10-22 15:40:09


Hello everybody,

I have just installed openmpi v. 1.2.5 under ubuntu 8.04 and I have compiled
the following "hello world" program:

------start code------
#include <stdio.h>
#include <mpi.h>

int main(int argc, char *argv[]){
int rank, size, len;
char hostname[256] = "";

MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Get_processor_name(hostname, &len);

printf("Hello World! I am %d of %d running on %s\n",
rank, size, hostname);

MPI_Finalize();

return 0;
}
------end code------

 which I think is pretty basic stuff. Anyway, when I run it (single node,
three cores), I get the following output:

mpiexec.openmpi -np 6 hello

Hello World! I am 0 of 1 running on el-torito
Hello World! I am 0 of 1 running on el-torito
Hello World! I am 0 of 1 running on el-torito
Hello World! I am 0 of 1 running on el-torito
Hello World! I am 0 of 1 running on el-torito
Hello World! I am 0 of 1 running on el-torito

where "el-torito" is the hostname. Shouldn't it be something like?:
Hello World! I am 0 of 6 running on el-torito
Hello World! I am 1 of 6 running on el-torito
Hello World! I am 2 of 6 running on el-torito
...
etc.

Any ideas as to why I keep getting wrong numbers for rank and number of
processes?

Greetings from Monterrey, Mexico

-- 
Victor M. Rosas García