Newsgroups: comp.parallel.mpi
From: c1akn@watson.ibm.com (Narayan Krishnamurthy)
Subject: MPICH : MPI rank order  mapping w.r.t process group file.
Organization: IBM T.J. Watson Research Center
Date: 10 Apr 1996 20:19:39 GMT
Message-ID: <4kh54r$1frh@watnews1.watson.ibm.com>

I have come across a one is to one mapping of the rank with respect to the 
order of the node names /host names mentioned in the proc group file.
For example  if the proc group file *.pg has the follwoing entries

host1.domain1   0  $HOME/MPI/a.out
host2.domain2   1  $HOME/MPI/a.out
host3.domain3   2  $HOME/MPI/a.out

the ranks of host1 is 0, host2 is 1 and host3 is 3. If I interchange host2 and
host 3 the ranks also follow suit. 
I am not sure whether this is a part of MPI standard or is it the underlying
p4 layer implementation specific??
 Would an MPI implementation for SP2 exhibit similar behaviour?
I ma trying to port MPI on to a communication layer of a program.The program
sends data by using a "node id" which is translated by the comm layer to the
corresponding "socket". How do I get to know which node has what rank at
runtime?
-regards
Narayan 




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