[Trilinos-Users] Epetra slow down instead of speed up on local machine (OpenMPI?)

[Gyorgy Matyasfalvi]

Hi Bart,

thanks for the quick response. I believe I didn't do that. This is what I
did:

***************************
$ make NO_AFFINITY=1
***************************

And I got the following output:
***********************************************************************************************
OpenBLAS build complete.

  OS               ... Linux
  Architecture     ... x86_64
  BINARY           ... 64bit
  C compiler       ... GCC  (command line : gcc)
  Fortran compiler ... GFORTRAN  (command line : gfortran)
  Library Name     ... libopenblas_sandybridgep-r0.2.8.a (Multi threaded;
Max num-threads is 32)

To install the library, you can run "make PREFIX=/path/to/your/installation
install".
***********************************************************************************************

I'll try to rebuild it as you suggested.
Thank you! Best,
Gyorgy




On Wed, Jun 18, 2014 at 2:03 PM, Bart Janssens <bart at bartjanssens.org>
wrote:

> On Wed, Jun 18, 2014 at 7:29 PM, Gyorgy Matyasfalvi <matyasfalvi at gmail.com
> > wrote:
>
>> On the local machine I'm using OpenMPI and OpenBLAS. On Stampede
>> MVAPICH2  and Intel MKL. I wonder if this could be the problem. Does anyone
>> have experience with OpenMPI and Epetra? It seems to me there is a
>> communication issue.
>>
>>
> Hi Gyorgy,
>
> Did you compile OpenBLAS without threads (i.e. set USE_THREAD = 0) ? This
> is necessary when combining with MPI, since otherwise you may overload the
> machine as OpenBLAS itself can spawn multiple threads.
>
> Cheers,
>
> Bart
>
>
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