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Subject: Re: [OMPI users] Newbie question
From: Gus Correa (gus_at_[hidden])
Date: 2011-01-12 15:11:30


Ralph Castain wrote:
> On Jan 12, 2011, at 12:54 PM, Tena Sakai wrote:
>
>> Hi Siegmar,
>>
>> Many thanks for your reply.
>>
>> I have tried man pages you mention, but one hurdle I am running into
>> is orte_hosts page. I don't find the specification of fields for
>> the file. I see an example:
>>
>> dummy1 slots=4
>> dummy2 slots=4
>> dummy3 slots=4
>> dummy4 slots=4
>> dummy5 slots=4
>>
>> Is the first field (dummyX) machine/node name?
>
> Yes
>
>> What is the definition
>> of slots? (Max number of processes to spawn?)
>
> Yes

Here we don't let 'slots' exceed the number of physical cores.
(Actually, Torque does this for us.)
I suppose this prevents the cores to be oversubscribed,
at least by default, right?

Gus Correa

>
>
>> Am I missing a different man page? Can you please shed some light?
>>
>> Thank you.
>>
>> Tena Sakai
>> tsakai_at_[hidden]
>>
>>
>>
>>
>> On 1/10/11 11:38 PM, "Siegmar Gross" <Siegmar.Gross_at_[hidden]>
>> wrote:
>>
>>> Hi,
>>>
>>>> What I want is to spawn a bunch of R slaves to other machines on
>>>> the network. I can spawn R slaves, as many as I like, to the local
>>>> machine, but I don t know how to do this with machines on the
>>>> network. That s what hosts parameter of mpi.spawn.Rslaves()
>>>> enables me to do, I think. If I can do that, then Rmpi has
>>>> function(s) to send command to each of the spawned slaves.
>>>>
>>>> My question is how can I get open MPI to give me those hosts
>>>> parameters.
>>> I am not quite sure if I understood your question, but when you
>>> read "man MPI_Comm_spawn" you can find the parameter "MPI_Info info"
>>> which allows to specify where and how to start processes. "man
>>> MPI_Info_create" shows you how to create an info object and "man
>>> MPI_Info_set" how to add a key/value pair. "man orte_hosts" shows
>>> you how you can build a hostfile. I do not know how to do these
>>> things in your language R but hopefully the information of the
>>> manual pages helps to solve your problem.
>>>
>>> Kind regards
>>>
>>> Siegmar
>>>
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
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>
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