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Subject: Re: [OMPI users] Bad performance when scattering big size of data?
From: Eugene Loh (eugene.loh_at_[hidden])
Date: 2010-10-04 22:18:11

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