26 lines
1.7 KiB
Markdown
26 lines
1.7 KiB
Markdown
## Runtime variables
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OpenBLAS checks the following environment variables on startup:
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* **OPENBLAS_NUM_THREADS=** the number of threads to use (for non-OpenMP-builds of OpenBLAS)
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* **OMP_NUM_THREADS=** the number of threads to use (for OpenMP builds - note that setting this may also affect any other OpenMP code)
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* **OPENBLAS_DEFAULT_NUM_THREADS=** the number of threads to use, irrespective if OpenBLAS was built for OpenMP or pthreads
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* **OPENBLAS_MAIN_FREE=1**" this can be used to disable automatic assignment of cpu affinity in OpenBLAS builds that have it enabled by default
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* **OPENBLAS_THREAD_TIMEOUT=** this can be used to define the length of time that idle threads should wait before exiting
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* **OMP_ADAPTIVE=1** this can be used in OpenMP builds to actually remove any surplus threads when the number of threads is decreased
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DYNAMIC_ARCH builds also accept the following:
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* **OPENBLAS_VERBOSE=** set this to "1" to enable a warning when there is no exact match for the detected cpu in the library
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set this to "2" to make OpenBLAS print the name of the cpu target it autodetected
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* **OPENBLAS_CORETYPE=** set this to one of the supported target names to override autodetection, e.g. OPENBLAS_CORETYPE=HASWELL
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* **OPENBLAS_L2_SIZE=** set this to override the autodetected size of the L2 cache where it is not reported correctly (in virtual environments)
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Deprecated variables still recognized for compatibilty:
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* **GOTO_NUM_THREADS=** equivalent to **OPENBLAS_NUM_THREADS**
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* **GOTOBLAS_MAIN_FREE** equivalent to **OPENBLAS_MAIN_FREE**
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* **OPENBLAS_BLOCK_FACTOR** this applies a scale factor to the GEMM "P" parameter of the block matrix code, see file driver/others/parameter.cen
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