===== OpenMP =====

== enable nested parallelism ==
environment variable **''OMP_NESTED=TRUE''** or call the runtime routine **''omp_set_nested()''** to 


=== environment ===

Lilmit the number of Threads:
environment variable **''OMP_NUM_THREADS''**


default thread stack size:
**''OMP_STACKSIZE''** / **''GOMP_STACKSIZE''** (in kilobytes)

The variable should contain a space- or comma-separated list of CPUs/cores.
**''GOMP_CPU_AFFINITY''**
single CPU numbers, range of CPUs (M-N), or a range with some stride (M-N:S). CPU
numbers are zero-based.

==== OS based parameters ====

Run a program only on selected cores (0 and 3):
<code bash>taskset -c 0,3 a.out</code>


You can also retrieve the CPU affinity of an existing task:
<code bash>taskset -c -p pid</code>

Or set it for a running program:
<code bash>$ taskset -c -p list pid</code>