Hi Steffen,

I'm not sure if this will help you (I'm by far no expert) but the mailing
group pointed by to using:
mpirun --use-hwthread-cpus

to solve something similar.

Kind regards,
Tim


On Tue, 16 Apr 2019 at 19:01, Steffen Christgau <christ...@cs.uni-potsdam.de>
wrote:

> Hi everyone,
>
> on my 2 cores/4 threads development platform I want to start programs
> via mpirun with over-subscription enabled by default. I have some
> external packages which have tests that use more than 2 processes. They
> all fail because Open MPI refuses them to run due to over-subscription.
> I know that I can enable over-subscription with mpirun --oversubscribe
> and that works well, but that would require to modify the packages'
> autotools files or the generated Makefiles with I found hardly convenient.
>
> I also tried two of the RMAPS MCA parameters:
>
>  - rmaps_base_no_oversubscribe
>  - rmaps_base_oversubscribe
>
> (btw, are they redundant? Having two of them and one is the negation of
> the other is quite confusing. The description in ompi_info reads quite
> similar for the two.)
>
> $ mpirun --mca rmaps_base_no_oversubscribe 0 --mca
> rmaps_base_oversubscribe 1 -n 4 hostname
> --------------------------------------------------------------------------
> There are not enough slots available in the system to satisfy the 4
> slots that were requested by the application:
>   hostname
>
> Either request fewer slots for your application, or make more slots
> available for use.
> --------------------------------------------------------------------------
>
> Setting the environment variables (OMPI_MCA_rmaps_...) did not help
> either. The same goes or the FAQ [1]:
>
> $ cat > my-hostfile
> localhost
> $ mpirun -np 4 --hostfile my-hostfile hostname
> --------------------------------------------------------------------------
> There are not enough slots available in the system to satisfy the 4
> slots...
>
> My Open MPI installation is a private build of version 4.0.0, configured
> with nothing more than ./configure --prefix=/some/where
> --enable-mpi-fortran
>
> How can I allow over-subscription by default? I am aware about
> performance implications, but it's only used for testing and
> development. I am not using a resource manager on that machine.
>
> Thanks in advance
>
> Regards, Steffen
>
> [1] https://www.open-mpi.org/faq/?category=running#oversubscribing
>
> _______________________________________________
> users mailing list
> users@lists.open-mpi.org
> https://lists.open-mpi.org/mailman/listinfo/users
>


-- 


*Timothy Jim**PhD Researcher in Aerospace*

Creative Flow Research Division,
Institute of Fluid Science, Tohoku University

www.linkedin.com/in/timjim/
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