Controlling the Number of Processors in exciting_smp

exciting
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Hi everyone,

I’m running exciting_smp (the shared-memory multiprocessing version) and trying to control the number of processors it uses. I’ve set OMP_NUM_THREADS=4 in my .bashrc to limit it to 4 threads. However, when I monitor the system while it’s running, I notice it seems to use more than that—around 6 or 7 processors at times.

Is there a way to ensure it only uses the specified number of processors, or am I missing something in the configuration? Any insights on controlling processor usage for exciting_smp would be greatly appreciated!

Thanks!

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Hi @sareh , setting OMP_NUM_THREADS in the .bashrc is a bad idea. This is going to affect all apps launched from your shell. It’s better to just export OMP_NUM_THREADS=4 on a per-session basis.

In my experience, openBLAS is extremely greedy when it comes to threads, and doesn’t necessarily respect OMP_NUM_THREADS. Try setting export OPENBLAS_NUM_THREADS=1. Similarly, MKL threads can be controlled with MKL_NUM_THREADS.

It’s likely to be whatever BLAS flavour you’re using that’s using the extra threads.

Cheers,
Alex

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Thank you so much, it works well.

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Hi, could you please provide me with the command ( steps) to make use of mpirun during running execution

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You’re using the wrong binary. See INSTALL.md:

By default, the mpiandsmp and smp versions of exciting are built, where mpiandsmp refers to a binary with both MPI and openMP parallelism enabled.

Running with MPI is the same for any program compiled with MPI support:

mpirun -np 4 exciting_mpismp
1 Like
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thanks , …
what about 2D , input files ,