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Subject: Re: [OMPI users] Some Newbie questions
From: vipin kumar (vipinkumar41_at_[hidden])
Date: 2009-06-29 02:19:05


Hi Ashika,

Q. Since I am using TCP/Ethernet I guess that MPI uses SSH/RSH to
communicate between peers.
Ans. May be you are right. I don't know exactly how peers communicate in MPI
environment, but I can say for sure that OpenMPI uses rsh/ssh as one of the
available launchers.

Q. And for that, each peer should have the copy of the application right?
Ans. Absolutely correct. But If you don't want to copy binaries manually you
should use "--preload-binary" option. OpenMPI will copy the executables in
remote nodes before launching processes, and will delete when job gets done.

It is almost always good to use latest version. "--preload-binary" option
may be absent in old versions.

Regards,

On Mon, Jun 29, 2009 at 10:30 AM, Ashika Umanga Umagiliya <
aumanga_at_[hidden]> wrote:

> Hi Vipin ,
> Thanks alot for the reply.
> I went through the FAQ and it also answered some of my questions.
>
> But my problem is, since I am using TCP/Ethernet I guess that MPI uses
> SSH/RSH to communicate between peers.
> And for that, each peer should have the copy of the application right?
>
> I use 1.2.7rc2 (from Debian/Lenny repo) , and I didn't see the option
> "--preload-binary" , is it because the lower version?
>
> Bets regards,
> umanga.
>
>
>
> vipin kumar wrote:
>
> Hi,
> I am not expert, I am user like you but I think I can help you,
>
> Q. After installing OpenMPI on each machine ,do i need to run a
> service/daemon on each machine?
> Ans. No, not at all, Open MPI takes care of that for you.
>
> Q. How does peers in MPI environment communicate ?
> Ans. Using Communicator(name of the group of processes to whom it belongs,
> technically handle) and rank of the process in that Communicator.
>
> Q. After implementing parallel program , do I have to install the
> application on every machine ?
> Ans. Not necessary. Use "--preload-binary" option while launching the
> application through mpirun or mpiexec.
>
> Useful links:
> 1. http://www.open-mpi.org/faq/?category=running#simple-spmd-run
> 2. http://www.open-mpi.org/faq/
> 3. man page for mpirun
>
> Regards,
> Vipin K.
>
> On Mon, Jun 29, 2009 at 8:21 AM, Ashika Umanga Umagiliya <
> aumanga_at_[hidden]> wrote:
>
>> Greeting all,
>>
>> I am new to Open MPI and I have some newbie questions. I have given 4
>> machines at our laboratory to set up Open MPI.Our net work is simply
>> TCP/Ethernet running Debian Linux.
>>
>> 1) After installing OpenMPI on each machine ,do i need to run a
>> service/daemon on each machine? (How does peers in MPI environment
>> communicate ?)
>>
>> 2) After implementing parallel program , do I have to install the
>> application on every machine ? (I thought the program automatically
>> propagated to other peers , like in RMI applications? )
>>
>>
>>
>> Thanks in advance,
>> Umanga
>>
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>
>
>
> --
> Vipin K.
> Research Engineer,
> C-Dot, Bangalore, India
>
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-- 
Vipin K.
Research Engineer,
C-Dot, Bangalore, India