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Subject: Re: [OMPI users] using ompi-server on a single node
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-01-06 09:29:17


The code that discovers local interfaces specifically ignores any
interfaces that are not up or are just local loopbacks. My guess is
that the person who wrote that code long, long ago was assuming that
the sole purpose was to talk to remote nodes, not to loop back onto
yourself.

I imagine it could be changed to include loopback, but I would first
need to work with other developers to ensure there are no unexpected
consequences in doing so.

Ralph

On Jan 5, 2009, at 3:49 PM, Terry Frankcombe wrote:

> But why doesn't tcp work on loopback?
>
>
> On Mon, 2009-01-05 at 07:25 -0700, Ralph Castain wrote:
>> It is currently a known limitation - shared memory currently only
>> works between procs from the same job. There is an enhancement coming
>> that will remove this restriction, but it won't be out for some time.
>>
>> Ralph
>>
>> On Jan 5, 2009, at 1:06 AM, Thomas Ropars wrote:
>>
>>> Hi,
>>>
>>> I've tried to use ompi-server to connect 2 processes belonging to
>>> different jobs but running on the same computer. It works when the
>>> computer has a network interface up. But if the only active network
>>> interface is the local loop, it doesn't work.
>>>
>>> According to what I understood reading the code, it is because no
>>> btl
>>> component can be used in this case. "tcp" is not used because
>>> usually
>>> it is the "sm" component that is used for processes on the same
>>> host.
>>> But in that case it doesn't work because "sm" is supposed to work
>>> only
>>> for processes of the same job.
>>>
>>> I know that this use-case is not very frequent :)
>>> But Is there a solution to make it work ? or is it a known
>>> limitation ?
>>>
>>> Regards
>>>
>>> Thomas
>>>
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
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