I tested a simple hello world program on 5 nodes each with dual
quad-core processors. I noticed that openmpi does not always follow
the order of the processors indicated in the machinefile. Depending
upon the number of processors requested, openmpi does some type of
sorting to find the best node fit for a particular job and runs on
them. Is there a way to make openmpi to turn off this sorting and
strictly follow the order indicated in the machinefile?
mpiexec supports three options to specify the machinefile -
default-machinefile, hostfile, and machinefile. Can anyone tell what
is the difference between these three options?
Any help would be greatly appreciated.