OMP build diagnostics (#4842)#4842
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Mar 18, 2026
Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Pull Request resolved: facebookresearch#4842 Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Mar 26, 2026
Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Pull Request resolved: facebookresearch#4842 Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Pull Request resolved: facebookresearch#4842 Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Pull Request resolved: facebookresearch#4842 Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary: Pull Request resolved: facebookresearch#4842 Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on `faiss:faiss_no_multithreading` instead of `faiss:faiss`. This adds `faiss::has_omp()`, which returns true if a `#pragma omp parallel` region had any effect through the use of a `reduction(max)` which would otherwise be stripped out. Note: 1. Compile-time check is not sufficient, as the `faiss_no_multithreading` and/or `faiss_omp_mock` targets control whether the `faiss/*.cpp` implementations have effective `#pragma omp` blocks. 2. Depending on the BUCK build mode, a `cpp_binary` which depends on `faiss:faiss_no_multithreading` and `faiss:faiss` *may or may not* link to implementations with OpenMP support. Reviewed By: subhadeepkaran Differential Revision: D94394555
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Summary:
Some tools which depend on FAISS recently became much slower because they were accidentally changed to depend on
faiss:faiss_no_multithreadinginstead offaiss:faiss.This adds
faiss::has_omp(), which returns true if a#pragma omp parallelregion had any effect through the use of areduction(max)which would otherwise be stripped out.Note:
faiss_no_multithreadingand/orfaiss_omp_mocktargets control whether thefaiss/*.cppimplementations have effective#pragma ompblocks.cpp_binarywhich depends onfaiss:faiss_no_multithreadingandfaiss:faissmay or may not link to implementations with OpenMP support.Reviewed By: subhadeepkaran
Differential Revision: D94394555