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Subject: Re: [OMPI users] How to specify hosts for MPI_Comm_spawn
From: Mark Borgerding (markb_at_[hidden])
Date: 2008-07-29 13:10:57


Umm ... what -hostfile file?

I am not starting anything via mpiexec/orterun so there is no
"-hostfile" argument AFAIK.
Is there some other way to communicate this? An environment variable or
mca param?

-- Mark

Ralph Castain wrote:
> Are the hosts where you want the children to go in your -hostfile
> file? All of the hosts you intend to use have to be in that file, even
> if they don't get used until the comm_spawn.
>
>
> On Jul 29, 2008, at 9:08 AM, Mark Borgerding wrote:
>
>> I've tried lots of different values for the "host" key in the info
>> handle.
>> I've tried hardcoding the hostname+ip entries in the /etc/hosts file
>> -- no luck. I cannot get my MPI_Comm_spawn children to go anywhere
>> else on the network.
>>
>> mpiexec can start groups on the other machines just fine. It seems
>> like there is some initialization that is done by orterun but not by
>> MPI_Comm_spawn.
>>
>> Is there a document that describes how the default process management
>> works?
>> I do not have infiniband, myrinet or any specialized rte, just ssh.
>> All the machines are CentOS 5.2 (openmpi 1.2.5)
>>
>>
>> -- Mark
>>
>> Ralph Castain wrote:
>>> The string "localhost" may not be recognized in the 1.2 series for
>>> comm_spawn. Do a "hostname" and use that string instead - should work.
>>>
>>> Ralph
>>>
>>> On Jul 28, 2008, at 10:38 AM, Mark Borgerding wrote:
>>>
>>>> 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.
>>>>
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>>>
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