[mvapich-discuss] Plans for MPMD support for mpirun_rsh

[Jonathan Perkins]

On Fri, Dec 11, 2009 at 02:20:27PM -0500, Gus Correa wrote:
> Hi Jonathan, list
>
> Thank you Jonathan for showing alternative ways to launch
> MPMD programs with MVAPICH.
> I haven't tried them but I will.
> I was under the impression that there were no MPMD mechanisms
> for MVAPIC2 at all, and it is great news that there are ways to do it.
>
> However, at least from the standpoint of system administration,
> there are advantages of using mpirun_rsh, instead of mpd,
> to launch programs.
> Moreover, MVAPICH2 seems to be migrating towards mpirun_rsh,
> or am I mistaken about that?

This is correct.

> Hence, the request for extending the mpirun_rsh
> capability to handle MPMD.

We agree and already have plans to add this flexibility to mpirun_rsh.

> Note that both myself and Craig administer clusters with
> a multiple users (large clusters, many users, in Craig's
> case, I suppose).
>
> Likewise, here I prefer to use the OSC mpiexec to launch programs
> compiled with MPICH2, instead of managing the mpd daemon population.
> This simplifies my system administration (and user education) work.
>
> Many thanks again,
> Gus Correa
> ---------------------------------------------------------------------
> Gustavo Correa
> Lamont-Doherty Earth Observatory - Columbia University
> Palisades, NY, 10964-8000 - USA
> ---------------------------------------------------------------------
>
>
> Jonathan Perkins wrote:
>> On Fri, Dec 11, 2009 at 12:23:38PM -0500, Gus Correa wrote:
>>> Hi Jonathan, Craig, list
>>
>> Hi Gus, comments inline.
>>
>>> 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.
>>
>> Agreed.
>>
>>> 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.
>>>
>>> Since MPICH2 supports MPMD, through the "mpiexec -configfile" option,
>>> I wonder how difficult it would be to port
>>> this capability to MVAPICH2 also.
>>
>> This limitation only exists with the current incarnation of mpirun_rsh.
>> You can use mpd/mpiexec to launch mvapich2.  Both mpiexec and mpirun_rsh
>> are built by default when building mvapich2-1.4, therefore you can use
>> mvapich2 for this applications in the same manner that you use mpich2.
>>
>>> 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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>
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-- 
Jonathan Perkins
http://www.cse.ohio-state.edu/~perkinjo
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