1.7 KiB
Runtime variables
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
DYNAMIC_ARCH builds also accept the following:
- OPENBLAS_VERBOSE= set this to "1" to enable a warning when there is no exact match for the detected cpu in the library set this to "2" to make OpenBLAS print the name of the cpu target it autodetected
- OPENBLAS_CORETYPE= set this to one of the supported target names to override autodetection, e.g. OPENBLAS_CORETYPE=HASWELL
- OPENBLAS_L2_SIZE= set this to override the autodetected size of the L2 cache where it is not reported correctly (in virtual environments)
Deprecated variables still recognized for compatibilty:
- GOTO_NUM_THREADS= equivalent to OPENBLAS_NUM_THREADS
- GOTOBLAS_MAIN_FREE equivalent to OPENBLAS_MAIN_FREE
- OPENBLAS_BLOCK_FACTOR this applies a scale factor to the GEMM "P" parameter of the block matrix code, see file driver/others/parameter.cen