[OMPI users] openmpi failed the hello world test

[Liu, Hanzhong]

Hi All:
       I installed the open mpi 1.6 on my desktop which is a intel quad core 
running 64bit ubuntu 12.04. After configuration and installation, I tested 
mpirun with hello world using 4 cpu. But only one cpu said "hello world". I'm 
wondering if any one experienced this. Thanks!