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Subject: Re: [OMPI users] Bad performance when scattering big size of data?
From: Terry Dontje (terry.dontje_at_[hidden])
Date: 2010-10-05 11:06:36

  On 10/05/2010 10:23 AM, Storm Zhang wrote:
> Sorry, I should say one more thing about the 500 procs test. I tried
> to run two 500 procs at the same time using SGE and it runs fast and
> finishes at the same time as the single run. So I think OpenMPI can
> handle them separately very well.
> For the bind-to-core, I tried to run mpirun --help but not find the
> bind-to-core info. I only see bynode or byslot options. Is it same as
> bind-to-core? My mpirun shows version 1.3.3 but ompi_info shows 1.4.2.
No, -bynode/-byslot is for mapping not binding. I cannot explain the
different release versions of ompi_info and mpirun. Have you done a
which to see where each of them are located. Anyways, 1.3.3 does not
have any of the -bind-to-* options.

> Thanks a lot.
> Linbao
> On Mon, Oct 4, 2010 at 9:18 PM, Eugene Loh <eugene.loh_at_[hidden]
> <mailto:eugene.loh_at_[hidden]>> wrote:
> Storm Zhang wrote:
> Here is what I meant: the results of 500 procs in fact shows
> it with 272-304(<500) real cores, the program's running time
> is good, which is almost five times 100 procs' time. So it can
> be handled very well. Therefore I guess OpenMPI or Rocks OS
> does make use of hyperthreading to do the job. But with 600
> procs, the running time is more than double of that of 500
> procs. I don't know why. This is my problem.
> BTW, how to use -bind-to-core? I added it as mpirun's options.
> It always gives me error " the executable 'bind-to-core' can't
> be found. Isn't it like:
> mpirun --mca btl_tcp_if_include eth0 -np 600 -bind-to-core
> scatttest
> Thanks for sending the mpirun run and error message. That helps.
> It's not recognizing the --bind-to-core option. (Single hyphen,
> as you had, should also be okay.) Skimming through the e-mail, it
> looks like you are using OMPI 1.3.2 and 1.4.2. Did you try
> --bind-to-core with both? If I remember my version numbers,
> --bind-to-core will not be recognized with 1.3.2, but should be
> with 1.4.2. Could it be that you only tried 1.3.2?
> Another option is to try "mpirun --help". Make sure that it
> reports --bind-to-core.
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Terry D. Dontje | Principal Software Engineer
Developer Tools Engineering | +1.781.442.2631
Oracle * - Performance Technologies*
95 Network Drive, Burlington, MA 01803
Email terry.dontje_at_[hidden] <mailto:terry.dontje_at_[hidden]>