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Add config option to leverage all cores for sabre #12780
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By default when running sabre in parallel we use a fixed number of threads (depending on optimization level). This was a tradeoff made for having deterministic results across multiple systems with a fixed seed set. However when running qiskit on systems with a lot of CPUs available we're leaving potential performance on the table by not using all the available cores. This new flag lets users opt-in to running sabre with n trials for n CPUs to potentially get better output results from the transpiler, with minimal to no runtime overhead, at the cost of the results not necessarily being reproducible when run on a different computer.
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Pull Request Test Coverage Report for Build 10081309595Warning: This coverage report may be inaccurate.This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.
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LGTM, not that I'll ever have the chance to see the effects of the option in my laptop 😝. I just left a few suggestions on the reno.
releasenotes/notes/add-sabre-all-threads-option-ad4ff7a4d045cb2b.yaml
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Co-authored-by: Elena Peña Tapia <[email protected]>
This commit refactors the logic added in the previous commit to a single helper function. This reduces the code duplication and makes it easier to work with. While doing this the logic has been updated so that when the flag is set and the default number of trials is larger than the CPU_COUNT we use the default. This means the logic when the flag is set is to run `max(default_trials, CPU_COUNT)` which should better match user expectations around the flag.
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LGTM
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LGTM too
* Add config option to leverage all cores for sabre By default when running sabre in parallel we use a fixed number of threads (depending on optimization level). This was a tradeoff made for having deterministic results across multiple systems with a fixed seed set. However when running qiskit on systems with a lot of CPUs available we're leaving potential performance on the table by not using all the available cores. This new flag lets users opt-in to running sabre with n trials for n CPUs to potentially get better output results from the transpiler, with minimal to no runtime overhead, at the cost of the results not necessarily being reproducible when run on a different computer. * Apply suggestions from code review Co-authored-by: Elena Peña Tapia <[email protected]> * Rework logic to use the default if larger than CPU_COUNT This commit refactors the logic added in the previous commit to a single helper function. This reduces the code duplication and makes it easier to work with. While doing this the logic has been updated so that when the flag is set and the default number of trials is larger than the CPU_COUNT we use the default. This means the logic when the flag is set is to run `max(default_trials, CPU_COUNT)` which should better match user expectations around the flag. --------- Co-authored-by: Elena Peña Tapia <[email protected]> (cherry picked from commit f8ac2ad)
* Add config option to leverage all cores for sabre By default when running sabre in parallel we use a fixed number of threads (depending on optimization level). This was a tradeoff made for having deterministic results across multiple systems with a fixed seed set. However when running qiskit on systems with a lot of CPUs available we're leaving potential performance on the table by not using all the available cores. This new flag lets users opt-in to running sabre with n trials for n CPUs to potentially get better output results from the transpiler, with minimal to no runtime overhead, at the cost of the results not necessarily being reproducible when run on a different computer. * Apply suggestions from code review Co-authored-by: Elena Peña Tapia <[email protected]> * Rework logic to use the default if larger than CPU_COUNT This commit refactors the logic added in the previous commit to a single helper function. This reduces the code duplication and makes it easier to work with. While doing this the logic has been updated so that when the flag is set and the default number of trials is larger than the CPU_COUNT we use the default. This means the logic when the flag is set is to run `max(default_trials, CPU_COUNT)` which should better match user expectations around the flag. --------- Co-authored-by: Elena Peña Tapia <[email protected]> (cherry picked from commit f8ac2ad) Co-authored-by: Matthew Treinish <[email protected]>
* Add config option to leverage all cores for sabre By default when running sabre in parallel we use a fixed number of threads (depending on optimization level). This was a tradeoff made for having deterministic results across multiple systems with a fixed seed set. However when running qiskit on systems with a lot of CPUs available we're leaving potential performance on the table by not using all the available cores. This new flag lets users opt-in to running sabre with n trials for n CPUs to potentially get better output results from the transpiler, with minimal to no runtime overhead, at the cost of the results not necessarily being reproducible when run on a different computer. * Apply suggestions from code review Co-authored-by: Elena Peña Tapia <[email protected]> * Rework logic to use the default if larger than CPU_COUNT This commit refactors the logic added in the previous commit to a single helper function. This reduces the code duplication and makes it easier to work with. While doing this the logic has been updated so that when the flag is set and the default number of trials is larger than the CPU_COUNT we use the default. This means the logic when the flag is set is to run `max(default_trials, CPU_COUNT)` which should better match user expectations around the flag. --------- Co-authored-by: Elena Peña Tapia <[email protected]>
In Qiskit 1.2.0 a new env variable was added to control the threading behavior of the routing and layout passes in the preset pass managers. You can see the details of this new option in the 1.2.0 release notes or in the PR Qiskit/qiskit#12780. This commit adds the documentation for this feature to the local configuration guide.
In Qiskit 1.2.0 a new env variable was added to control the threading behavior of the routing and layout passes in the preset pass managers. You can see the details of this new option in the 1.2.0 release notes or in the PR Qiskit/qiskit#12780. This commit adds the documentation for this feature to the local configuration guide. --------- Co-authored-by: Eric Arellano <[email protected]> Co-authored-by: abbycross <[email protected]>
Summary
By default when running sabre in parallel we use a fixed number of threads (depending on optimization level). This was a tradeoff made for having deterministic results across multiple systems with a fixed seed set. However when running qiskit on systems with a lot of CPUs available we're leaving potential performance on the table by not using all the available cores. This new flag lets users opt-in to running sabre with n trials for n CPUs to potentially get better output results from the transpiler, with minimal to no runtime overhead, at the cost of the results not necessarily being reproducible when run on a different computer.
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