Another sanity think to try is see if you can run your test program on just one of the nodes?  If that works more than likely MPI is having issues setting up connections between the nodes.


On 6/7/2012 6:06 AM, Duke wrote:
Hi again,

Somehow the verbose flag (-v) did not work for me. I tried --debug-daemon and got:

[mpiuser@fantomfs40a ~]$ mpirun --debug-daemons -np 3 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
Daemon was launched on hp430a - beginning to initialize
Daemon [[34432,0],1] checking in as pid 3011 on host hp430a
<stuck here>

Somehow the program got stuck when checking on hosts. The secure log on hp430a showed that mpiuser logged in just fine:

tail /var/log/secure
Jun  7 17:07:31 hp430a sshd[3007]: Accepted publickey for mpiuser from port 34037 ssh2
Jun  7 17:07:31 hp430a sshd[3007]: pam_unix(sshd:session): session opened for user mpiuser by (uid=0)

Any idea where/how/what to process/check?



On 6/7/12 4:38 PM, Duke wrote:
Hi Jingha,

On 6/7/12 4:28 PM, Jingcha Joba wrote:
Hello Duke,
Welcome to the forum.
The way openmpi schedules by default is to fill all the slots in a host, before moving on to next host.
Check this link for some info:

Thanks for quick answer. I checked the FAQ, and tried with processes more than 2, but somehow it got stalled:

[mpiuser@fantomfs40a ~]$ mpirun -v -np 4 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
^Cmpirun: killing job...

I tried --host flag and it got stalled as well:

[mpiuser@fantomfs40a ~]$ mpirun -v -np 4 --host hp430a,hp430b ./test/mpihello

My configuration must be wrong somewhere. Anyidea how I can check the system?




On Thu, Jun 7, 2012 at 2:11 AM, Duke <> wrote:
Hi folks,

Please be gentle to the newest member of openMPI, I am totally new to this field. I just built a test cluster with 3 boxes on Scientific Linux 6.2 and openMPI (Open MPI 1.5.3), and I wanted to test how the cluster works but I cant figure out what was/is happening. On my master node, I have the hostfile:

[mpiuser@fantomfs40a ~]$ cat .mpi_hostfile
# The Hostfile for Open MPI
fantomfs40a slots=2
hp430a slots=4 max-slots=4
hp430b slots=4 max-slots=4

To test, I used the following c code:

[mpiuser@fantomfs40a ~]$ cat test/mpihello.c
/* program hello */
/* Adapted from mpihello.f by drs */

#include <mpi.h>
#include <stdio.h>

int main(int argc, char **argv)
 int *buf, i, rank, nints, len;
 char hostname[256];

 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 printf("Hello world!  I am process number: %d on host %s\n", rank, hostname);
 return 0;

and then compiled and ran:

[mpiuser@fantomfs40a ~]$ mpicc -o test/mpihello test/mpihello.c
[mpiuser@fantomfs40a ~]$ mpirun -np 2 --machinefile /home/mpiuser/.mpi_hostfile ./test/mpihello
Hello world!  I am process number: 0 on host fantomfs40a
Hello world!  I am process number: 1 on host fantomfs40a

Unfortunately the result did not show what I wanted. I expected to see somethign like:

Hello world!  I am process number: 0 on host hp430a
Hello world!  I am process number: 1 on host hp430b

Anybody has any idea what I am doing wrong?

Thank you in advance,


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