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Subject: Re: [OMPI users] Open MPI performance on Amazon Cloud
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-03-19 14:19:06


Yes, it is -- sometimes we get so caught up in other issues that user emails slip through the cracks. Sorry about that!

I actually have little experience with EC2 -- other than knowing that it works, I don't know much about the performance that you can extract from it. I have heard issues about non-uniform latency between MPI processes because you really don't know where the individual MPI processes may land (network- / VM-wise). It suggests to me that EC2 might be best suited for compute-bound jobs (vs. latency-bound jobs).

Amusingly enough, the first time someone reported an issue with Open MPI on EC2, I tried to submit a help ticket to EC2 support saying, "I'm one of the Open MPI developers ... blah blah blah ... is there anything I can do to help?" The answer I got back was along the lines of, "You need to have a paid EC2 support account before we can help you." I think they missed the point, but oh well. :-)

On Mar 12, 2010, at 12:10 AM, Hammad Siddiqi wrote:

> Dear All,
> Is this the correct forum for sending these kind of emails. please let me know if there is some other mailing list.
> Thank
> Best Regards,
> Hammad Siddiqi
> System Administrator,
> Centre for High Performance Scientific Computing,
> School of Electrical Engineering and Computer Science,
> National University of Sciences and Technology,
> H-12, Islamabad.
> Office : +92 (51) 90852207
> Web: http://hpc.seecs.nust.edu.pk/~hammad/
>
>
> On Sat, Feb 27, 2010 at 10:07 PM, Hammad Siddiqi <hammad.siddiqi_at_[hidden]> wrote:
> Dear All,
>
> I am facing very wierd results of OpenMPI 1.4.1 on Amazon EC2. I have
> used Small Instance and and High CPU medium instance for benchmarking
> latency and bandwidth. The OpenMPI was configured with the default
> options. when the code is run in the cluster mode the latency and
> bandwidth of Amazon EC2 Small instance is really less than that of
> Amazon EC2 High CPU medium instance. To my understanding the
> difference should not be that much. The following are the links to
> graphs ad their data:
>
> Data: http://hpc.seecs.nust.edu.pk/~hammad/OpenMPI,Latency-BandwidthData.jpg
> Graphs: http://hpc.seecs.nust.edu.pk/~hammad/OpenMPI,Latency-Bandwidth.jpg
>
>
> Please have a look on them.
>
> Is anyone else facing the same problem. Any guidance in this regard
> will highly be appreciated.
>
> Thank you.
>
>
> --
> Best Regards,
> Hammad Siddiqi
> System Administrator,
> Centre for High Performance Scientific Computing,
> School of Electrical Engineering and Computer Science,
> National University of Sciences and Technology,
> H-12, Islamabad.
> Office : +92 (51) 90852207
>
> _______________________________________________
> users mailing list
> users_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/users

-- 
Jeff Squyres
jsquyres_at_[hidden]
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