[Multiple node groups in Scyld]

Joey Raheb joeyraheb at usa.net
Tue Jun 12 17:24:29 PDT 2001

It should be the same as regular MPI.  For example if you wanted to run on
nodes 0-3, then create a machinefile like:


then you call mpi like:
>mpirun -np 4 -machinefile name_of_the_machinefile executable.

Then if you want to run on 4-8 you would do the same as above but insert
node4-node8 in the new machinefile and call mpirun the same way.

Hope this helps,

Karl Kosack <kosack at hbar.wustl.edu> wrote:

I have recently set up a beowulf cluster for scientific computing using
the Scyld distribution.  Scyld was very easy to set up and configure, but
I have one major question for which I can't seem to find an answer: How
can I run more than one MPI program on the cluster on different ranges of

For example, there are times where I would like to run one program
on nodes 0-3 and another on 4-8.  The "mpirun" command that comes with
Scyld only seems to let you supply a number of node numbers and not a

If I run "mpirun --nodes 4 myprog1" and then "mpirun --nodes 4 myprog2"
then myprog1 and myprog2 both run on nodes 0-3.

I know in other MPI  implementations, it is possible to create a
file of machine names which specifies which nodes to use for a particular
job, but I can't seem to find that capability in the Scyld distribution.
I imagine there must be a simple way to do this, since a large cluster
wouldn't be very useful without it.  Can anyone help me?


  Karl Kosack <kosack at hbar.wustl.edu>
  Physics Department
  Washington University
  One Brookings Drive, Box 1105
  St. Louis, MO 63130

 office: (314) 935-5035  (Compton 267)

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