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Subject: Re: [OMPI users] Newbie question
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-01-11 06:33:37

You might be confusing LAM/MPI with Open MPI -- they're two different software code bases. They both implement the MPI standard, but they're entirely different software projects. Indeed, all the LAM/MPI developers (including me) abandoned LAM/MPI several years ago and went to work on Open MPI -- think of Open MPI as a "next generation" LAM/MPI.

To be clear, LAM node numbers and lamnodes() (and all the other LAM references) will not work with Open MPI. Those are details from an entirely different implementation of MPI. Hence, if your R MPI has instructions specific to LAM/MPI, they are likely not relevant at all for Open MPI.

You probably need to check back with the R MPI folks and see how to do what you need to do in Open MPI. Most of us here aren't familiar with R (which is why I suspect you're getting a motley assortment of answers); checking with the maintainers might be best.

I know that there has been a bunch of work with R MPI on Open MPI, so I'd be surprised if there wasn't a way to do what you need.

On Jan 10, 2011, at 8:04 PM, Tena Sakai wrote:

> Hi,
> I am an mpi newbie. My open MPI is v 1.4.3, which I compiled
> on a linux machine.
> I am using a language called R, which has an mpi interface/package.
> It appears that it is happy, on the surface, with the open MPI I installed.
> There is an R function called mpi.spawn.Rslaves(). An argument to
> this function is nslaves. I can issue, for example,
> mpi.spawn.Rslaves( nslaves=20 )
> And it spawns 20 slave processes. The trouble is that it is all on the
> same node as that of the master. I want, instead, these 20 (or more)
> slaves spawned on other machines on the network.
> It so happens the mpi.spawn.Rslaves() has an extra argument called
> hosts. Here’s the definition of hosts from the api document: “NULL or
> LAM node numbers to specify where R slaves to be spawned.” I have
> no idea what LAM node is, but there is a funciton called lamhosts().
> which returns a bit verbose message:
> It seems that there is no lamd running on the host compute-0-0.local.
> This indicates that the LAM/MPI runtime environment is not operating.
> The LAM/MPI runtime environment is necessary for the "lamnodes" command.
> Please run the "lamboot" command the start the LAM/MPI runtime
> environment. See the LAM/MPI documentation for how to invoke
> "lamboot" across multiple machines.
> Here’s my question. Is there such command as lamboot in open MPI 1.4.3?
> Or am I using a wrong mpi software? In a FAQ I read that there are other
> MPI software (FT-mpi, LA-mpi, LAM-mpi), but I had notion that open MPI
> is to have functionalities of all. Is this a wrong impression?
> Thank you for your help.
> Tena Sakai
> tsakai_at_[hidden]
> _______________________________________________
> users mailing list
> users_at_[hidden]

Jeff Squyres
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