[mvapich-discuss] Plans for MPMD support for mpirun_rsh

[Craig Tierney]

Gus Correa wrote:
> Hi Jonathan, Craig, list
> 
> I second Craig's question and request for MPMD support.
> That would be really great for Earth Science applications,
> maybe for other areas as well.
> 
> For instance, the whole atmosphere/ocean/climate community
> relies mostly on MPMD for most modern coupled climate models.
> Typically you have five or more executables working in MPMD mode:
> atmosphere, ocean, ice, land, etc, coordinated by a flux coupler.
> Here is one example:
> http://www.ccsm.ucar.edu/models/ccsm3.0/
> Other computational frameworks in Earth Science follow the same
> paradigm and require MPMD.
> 
> MPMD is particularly convenient in Linux clusters,
> because it can keep reasonably small sized executables,
> stacks, heaps, etc, whereas a SPMD executable containing
> all code for multiple component models tends to be much larger,
> and may even lead to memory paging, which is disastrous for MPI.
> 
> We are currently restricted to use OpenMPI and MPICH2 for
> these MPMD models, which are at the forefront of our research efforts.
> It is a pity that so far we cannot use MVAPICH2 to test and
> run these MPMD programs, although we use MVAPICH2
> for smaller and less challenging SPMD programs with excellent results.
> 

Gus,

Have you tried just using mpd/mpiexec in mvapich2?  The docs
say that it is depreciated and mpirun_rsh is the method going
forward (although it doesn't work with MPMD or Totalview yet).

I have though the mpd method was bad because it made no sense
to launch the mpd clients by ssh, then start the application.
Why not just start the application?

However, mpdboot is much better than it has been in the past.
I am using it right now to test the Intel MPI 4.0 beta because
it doesn't support mpirun_rsh.  I am also testing it in
Mvapich2 1.4.  It isn't desirable, but it works.  I haven't
tested an MPMD application yet though.

Craig



> Since MPICH2 supports MPMD, through the "mpiexec -configfile" option,
> I wonder how difficult it would be to port
> this capability to MVAPICH2 also.
> 
> Thank you very much,
> Gus Correa
> ---------------------------------------------------------------------
> Gustavo Correa
> Lamont-Doherty Earth Observatory - Columbia University
> Palisades, NY, 10964-8000 - USA
> ---------------------------------------------------------------------
> 
> 
> 
> Jonathan Perkins wrote:
>> On Mon, Dec 07, 2009 at 03:52:18PM -0700, Craig Tierney wrote:
>>> >From what I can tell in the documentation, mpirun_rsh
>>> is the favored launch mechanism.  However, I don't see
>>> a way to launch MPMD applications.   If I read
>>> the docs correctly (that it isn't supported), Are there
>>> plans to add this to mpirun_rsh?
>>
>> Yes, we plan to add this in a future mvapich2 release.
>>
>>> Craig
>>>
>>> -- 
>>> Craig Tierney (craig.tierney at noaa.gov)
>>> _______________________________________________
>>> mvapich-discuss mailing list
>>> mvapich-discuss at cse.ohio-state.edu
>>> http://mail.cse.ohio-state.edu/mailman/listinfo/mvapich-discuss
>>
>>
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-- 
Craig Tierney (craig.tierney at noaa.gov)