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Subject: Re: [OMPI users] MPI_Comm_spawn and oreted
From: Jerome BENOIT (ml.jgmbenoit_at_[hidden])
Date: 2009-04-16 10:57:20


Hi,

thanks for the reply.

Ralph Castain wrote:
> The orteds don't pass anything from MPI_Info to srun during a
> comm_spawn. What the orteds do is to chdir to the specified wdir before
> spawning the child process to ensure that the child has the correct
> working directory, then the orted changes back to its default working
> directory.
>
> The orted working directory is set by the base environment. So your
> slurm arguments cause *all* orteds to use the specified directory as
> their "home base". They will then use any given wdir keyval when they
> launch their respective child processes, as described above.
>
> As a side note, it isn't clear to me why you care about the orted's
> working directory. The orteds don't write anything there, or do anything
> with respect to their "home base" - so why would this matter? Or are you
> trying to specify the executable's path relative to where the orted is
> sitting?

Let be specific. My worker nodes are homeless: the /home directory is automounted
(when needed) from the master node: orteds dont write anything, but they keep it mounted !
The idea is to avoid this by specifying a local working directory.

Jerome

>
>
> On Apr 16, 2009, at 4:02 AM, Jerome BENOIT wrote:
>
>> Hi !
>>
>> finally I got it:
>> passing the mca key/value `"plm_slurm_args"/"--chdir /local/folder"'
>> does the trick.
>>
>> As a matter of fact, my code pass the MPI_Info key/value
>> `"wdir"/"/local/folder"'
>> to MPI_Comm_spawn as well: the working directories on the nodes of the
>> spawned programs
>> are `nodes:/local/folder' as expected, but the working directory of
>> the oreted_s
>> is the working directory of the parent program. My guess is that the
>> MPI_Info key/vale
>> may also be passed to `srun'.
>>
>> hth,
>> Jerome
>>
>>
>>
>> Jerome BENOIT wrote:
>>> Hello Again,
>>> Jerome BENOIT wrote:
>>>> Hello List,
>>>>
>>>> I have just noticed that, when MPI_Comm_spawn is used to launch
>>>> programs around,
>>>> oreted working directory on the nodes is the working directory of
>>>> the spawnning program:
>>>> can we ask to oreted to use an another directory ?
>>> Changing the working the directory via chdir before spawning with
>>> MPI_Comm_spawn
>>> changes nothing: the oreted working directory on the nodes seems to
>>> be imposed
>>> by something else. As run OMPI on top of SLURM, I guess this is
>>> related to SLURM.
>>> Jerome
>>>>
>>>> Thanks in advance,
>>>> Jerome _______________________________________________
>>>> users mailing list
>>>> users_at_[hidden]
>>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>>
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