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Subject: Re: [OMPI users] MPI_Spawn and process allocation policy
From: Brian Budge (brian.budge_at_[hidden])
Date: 2012-10-01 13:27:15


On Wed, Sep 12, 2012 at 10:23 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>
> On Sep 12, 2012, at 9:55 AM, Brian Budge <brian.budge_at_[hidden]> wrote:
>
>> On Wed, Aug 17, 2011 at 12:05 AM, Simone Pellegrini
>> <spellegrini_at_[hidden]> wrote:
>>> On 08/16/2011 11:15 PM, Ralph Castain wrote:
>>>>
>>>> I'm not finding a bug - the code looks clean. If I send you a patch, could
>>>> you apply it, rebuild, and send me the resulting debug output?
>>>
>>> yes, I could do that. No problem.
>>>
>>> thanks again, Simone
>>
>> Hi all -
>>
>> Did this ever get resolved?
>
> Not sure to what you are referring - this thread ran all over the place, and I confess I've lost track.
>
>> I've been having trouble specifying the
>> hosts to run my spawned processes on. Is there an example of how to
>> do this?
>
> Did you look at "man MPI_Comm_spawn"? It lists all the info keys we recognize and what they do
>
>> Also, I'm assuming that any host given must also be listed
>> in the hostfile?
>
> Not in the updated 1.6 branch and above - to include the upcoming 1.6.2 release.
>

Hi Ralph -

I'm using a nightly build of 1.6.2. I have tried the following:

* Run the master process as a singleton OR via mpirun without setting
any host information via env or command line
Set the MPI_Info "host" key to the comma delimited list of hosts
Launch the processes via MPI_Comm_spawn

Result: All processes run on the same node that runs the singleton.

* Run the master process as a singleton OR via mpirun without setting
any host information via env or command line
Set the MPI_Info "host" key to an individual host for each info in an
array of info objects
Launch the processes via MPI_Comm_spawn_multiple

Result: "There are no allocated resources for the application
  ./driver
that match the requested mapping:

Verify that you have mapped the allocated resources properly using the
--host or --hostfile specification"

If I set the hostfile via environment variable, or if I run with
mpirun and set the hostfile via the command line, everything works as
expected. Is there something additional to the MPI_Info key "host"
that needs to be set?

Thanks,
  Brian