[mvapich-discuss] FW: programming problems

[Bainbridge, Brian]

Hi There,

I'm attempting to get some code running on MVAPICH2 on our cluster but initially I'm trying to get mpd to run properly

As far as I can tell I've got it running ok. mpdtrace produces:

[bba at node001 sge_test]$ mpdtrace
node001
node005
node012
node053
...
node025
node023
node024
node022

Showing all 75 nodes as being part of the mpd ring.

If I run an intrinsic program I get sensible results:

[bba at node001 sge_test]$ mpiexec -n 16 /bin/hostname
node048
node001
node047
node045
node042
node053
node011
node052
node050
node051
node049
node044
node013
node005
node012
node046

However, if I try to run an MPI program I get the following:

[bba at node001 sge_test]$ mpiexec -n 16 ./hello_f90
 Hello, world, I am             0  of            16  on
 node001
 Hello, world, I am             1  of            16  on  Hello, world, I am             2  of            16  on
 Hello, world, I am             5  of            16  on
 node001
 Hello, world, I am             3  of            16  on
 node001
 Hello, world, I am             4  of            16  on

 node001
 node001
 Hello, world, I am             6  of            16  on
 node001
 Hello, world, I am             7  of            16  on  Hello, world, I am             8  of            16  on
 node001
 Hello, world, I am            15  of            16  on
 node001

 node001
 Hello, world, I am             9  of            16  on
 node001
 node001
 Hello, world, I am            10  of            16  on
 node001
 Hello, world, I am            11  of            16  on
 node001
 Hello, world, I am            12  of            16  on
 node001
 Hello, world, I am            13  of            16  on
 node001
 Hello, world, I am            14  of            16  on
 node001

Which is more or less what I'm after, except all the programs are running on one node instead of being spread over multiple nodes.

I don't understand why the MPI code isn't running on different processes in the same way as /bin/hostname. The code is just
reading the environment variable HOSTNAME and printing it out. If I start running the code from a different node it prints that
node out instead:

[bba at node002 sge_test]$ mpiexec -n 16 ./hello_f90
 Hello, world, I am             0  of            16  on  Hello, world, I am             2  of            16  on
 node002
 node002
...

I've waded through the documentation I could find but it hasn't helped. As far as the documentation goes if it works with
/bin/hostname it should work with MPI.

I'd be grateful for any help on this.

Brian

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