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Subject: Re: [OMPI users] How to specify hosts for MPI_Comm_spawn
From: Mark Borgerding (markb_at_[hidden])
Date: 2008-07-28 12:38:39


When I add the info parameter in MPI_Comm_spawn, I get the error
"Some of the requested hosts are not included in the current allocation
for the application:
[...]
Verify that you have mapped the allocated resources properly using the
--host specification."

Here is a snippet of my code that causes the error:

    MPI_Info info;
    MPI_Info_create( &info );
    MPI_Info_set(info,"host","localhost");
    MPI_Comm_spawn( cmd , MPI_ARGV_NULL , nkids , info , 0 ,
MPI_COMM_SELF , &kid , errs );

Mark Borgerding wrote:
> Thanks, I don't know how I missed that. Perhaps I got thrown off by
> "Portable programs not requiring detailed control over process
> locations should use MPI_INFO_NULL."
>
> If there were a computing equivalent of Maslow's Hierarchy of Needs,
> functioning would be more fundamental than portability :)
>
> -- Mark
>
>
> Ralph Castain wrote:
>> Take a look at the man page for MPI_Comm_spawn. It should explain
>> that you need to create an MPI_Info key that has the key of "host"
>> and a value that contains a comma-delimited list of hosts to be used
>> for the child processes.
>>
>> Hope that helps
>> Ralph
>>
>> On Jul 28, 2008, at 8:54 AM, Mark Borgerding wrote:
>>
>>> How does openmpi decide which hosts are used with MPI_Comm_spawn?
>>> All the docs I've found talk about specifying hosts on the
>>> mpiexec/mpirun command and so are not applicable.
>>> I am unable to spawn on anything but localhost (which makes for a
>>> pretty uninteresting cluster).
>>>
>>> When I run
>>> ompi_info --param rds hostfile
>>> It reports MCA rds: parameter "rds_hostfile_path"
>>> (current value:
>>> "/usr/lib/openmpi/1.2.5-gcc/etc/openmpi-default-hostfile")
>>> I tried changing that file but it has no effect.
>>>
>>>
>>> I am using
>>> openmpi 1.2.5
>>> CentOS 5.2
>>> ethernet TCP
>>>
>>>
>>> -- Mark
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>

-- 
Mark Borgerding
3dB Labs, Inc
Innovate.  Develop.  Deliver.