mirror of https://github.com/Qiskit/qiskit.git
24 lines
1.1 KiB
YAML
24 lines
1.1 KiB
YAML
---
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upgrade:
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The maximum number of trials evaluated when searching for the best
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layout using :class:`.VF2Layout` and :class:`.VF2PostLayout` is now
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limited in
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:func:`qiskit.transpiler.preset_passmanagers.level_1_pass_manager`,
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:func:`qiskit.transpiler.preset_passmanagers.level_2_pass_manager`,
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and
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:func:`qiskit.transpiler.preset_passmanagers.level_3_pass_manager`
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to ``2,500``, ``25,000``, and ``250,000``, respectively. Previously,
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all possible layouts were evaluated. This change was made to prevent
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transpilation from hanging during layout scoring for circuits with many
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connected components on larger devices, which scales combinatorially
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since each connected component must be evaluated in all possible
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positions on the device. To perform a full search as
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before, manually run :class:`.VF2PostLayout` over the transpiled circuit
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in strict mode, specifying ``0`` for ``max_trials``.
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fixes:
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Fixed a potential performance scaling issue with layout scoring in preset
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pass managers, which could occur when transpiling circuits with many
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connected components on large devices.
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