MPS: Added thresholds to loops that use parallelization #638
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atilag
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Feb 26, 2020
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Good to see that we have fixed the performance degradation!
So a comment in general, there's no need for commenting code, we can safely remove it because we can always go back in git history and see the old code.
Could you remove all commented code that you see in the MPS simulator?
Thanks!!
src/simulators/matrix_product_state/matrix_product_state_internal.cpp
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src/simulators/matrix_product_state/matrix_product_state_internal.cpp
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src/simulators/matrix_product_state/matrix_product_state_internal.hpp
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src/simulators/matrix_product_state/matrix_product_state_tensor.hpp
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…skit-aer into parallelization
mtreinish
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Mar 2, 2020
* Adding conditions on invoking parallelization (cherry picked from commit 7fb9147)
hhorii
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Apr 9, 2020
* Adding conditions on invoking parallelization
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Summary
Parallelization on for-loops without a threshold caused a severe deterioration of performance in MPS. I added reasonable thresholds that bring the performance back to the previous values. Determining the optimal values should be done in future work, but for now this is good enough.
Details and comments
It would be great to include this in the current release because it dramatically affects performance of MPS. This closes issue #619.