diff --git a/docs/Multithreading.md b/docs/Multithreading.md index d8f8b13f40..11ca7d1d70 100644 --- a/docs/Multithreading.md +++ b/docs/Multithreading.md @@ -147,7 +147,14 @@ $ GOMP_CPU_AFFINITY="0-15" BLIS_NUM_THREADS=16 ./my_blis_program ``` Either of these approaches causes BLIS to automatically determine a reasonable threading strategy based on what is known about the operation and problem size. If `BLIS_NUM_THREADS` is not set, BLIS will attempt to query the value of `BLIS_NT` (a shorthand alternative to `BLIS_NUM_THREADS`). If neither variable is defined, then BLIS will attempt to read `OMP_NUM_THREADS`. If none of these variables is set, the default number of threads is 1. -**Note**: We *highly* discourage use of the `OMP_NUM_THREADS` environment variable to specify multithreading within BLIS and may remove support for it in the future. If you wish to set parallelism globally via environment variables, please use `BLIS_NUM_THREADS`. +**Note**: If none of `BLIS_NT`/`BLIS_NUM_THREADS` are defined, BLIS will fall back to use +the standardized `OMP_NUM_THREADS` environment variable. +By having an application specific environment variable one can fine-tune the thread +utilization, e.g. to run OpenMP constructs using 4 threads, and BLIS with 2 threads: +``` +$ OMP_NUM_THREADS=4 BLIS_NUM_THREADS=2 ./my_omp_blis_program +``` + ### Environment variables: the manual way