CODEWITHSUNDEEP
openmdao
Rob Falck
Rob Falck

Reputation: 2704

OpenMDAO 1.x relevance reduction

I have a component in OpenMDAO without outputs that serves to provide inputs to the rest of the group. apply_linear in that component is being called despite the fact that the output of it is not connected. Shouldn't the relevance reduction algorithm in OpenMDAO 1.x figure out that apply_linear for this method never needs to be called?

Upvotes: 0

Views: 75

Answers (2)

Bret Naylor
Bret Naylor

Reputation: 754

My reputation isn't high enough yet to leave comments, so I'm just adding another answer instead. I just wanted to mention that if you're not running under MPI, activating single_voi_relevance_reduction is essentially free. The real increase in memory use isn't due to the vectors themselves, but instead it's due to the index arrays that we store in order to transfer the data from source arrays to target arrays. We're forced to use index arrays under MPI, because PETSc requires it, but when we're not using MPI we use python slice objects to do our data transfer. Slice objects require very little memory.

Upvotes: 2

Kenneth Moore
Kenneth Moore

Reputation: 2202

As it turns out, relevance reduction on a per-variable basis isn't turned on by default. You can turn it on with:

    prob.root.ln_solver = LinearGaussSeidel()
    prob.root.ln_solver.options['single_voi_relevance_reduction'] = True

This options is set to False by default because it does use more memory by allocating separate vectors for each quantity of interest (though each vector is smaller because it only contains relevant variables, but the total size may be larger.) Also, relevance-reduction is only applicable when using Linear Gauss Seidel as the top linear solver.

Upvotes: 2

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