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Subject: Re: [OMPI users] MPI_Spawn and process allocation policy
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-10-01 13:33:49


Yes, that is the expected behavior as you describe it.

If you want to run on hosts that are not already provided (via hostfile in the environment or on the command line), then you need to use the "add-host" or "add-hostfile" MPI_Info key. See "man MPI_Comm_spawn" for details.

On Oct 1, 2012, at 10:27 AM, Brian Budge <brian.budge_at_[hidden]> wrote:

> 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