Newsgroups: comp.parallel.mpi
From: johns@cs.umr.edu (John Stone)
Subject: Re: MPI over 32 workstations
Organization: Computer Science Dept, Univ. of Missouri-Rolla
Date: 15 Feb 1997 10:15:04 GMT
Message-ID: <5e42b8$gb6@pluto.er.usgs.gov>


Hi..

  I don't believe you'll need to edit /etc/system, for only 32 machines..
If your shell is 'csh' try typing 'limit', you'll see something akin 
to the following:

orion - johns:/disk4/os/packages/build/Mesa-2.1 % limit
cputime         unlimited
filesize        unlimited
datasize        523256 kbytes
stacksize       8192 kbytes
coredumpsize    0 kbytes
descriptors     64 
memorysize      unlimited
orion - johns:/disk4/os/packages/build/Mesa-2.1 % 

Try doing: 
orion - johns:/disk4/os/packages/build/Mesa-2.1 % limit descriptors unlimited
orion - johns:/disk4/os/packages/build/Mesa-2.1 % limit
cputime         unlimited
filesize        unlimited
datasize        523256 kbytes
stacksize       8192 kbytes
coredumpsize    0 kbytes
descriptors     1024 
memorysize      unlimited
orion - johns:/disk4/os/packages/build/Mesa-2.1 % 

This will give you 1024 descriptors.

If these are not sufficient, then you will probably need to edit 
/etc/system...

You'll need to make sure that when mpirun shells over to the other machines,
that it picks up this limit change.  You could do this numerous ways, 
but that's dependent on how your systems are setup, and wether or not
you want to edit the mpirun script etc..
I've had to hack mpirun in the past to make it work on AFS based systems that
had a broken 'rsh' among other things.  (a long while back)

Note: editing /etc/system typically buys you nothing unless your user set 
      limits are also maxed out.  If there is a 'default' setting for 
      descriptors in /etc/system, that might help you out though.
      Also, only root can/should be able to edit /etc/system, so if this
      is not you, you'll need your admin to help if it goes that far.

   John Stone
   johns@heuris.com
   johns@cs.umr.edu
   j.stone@acm.org