GOMP_CPU_AFFINITY="0 3 1-2 4-15:2" will bind the initial thread
to CPU 0, the second to CPU 3, the third to CPU 1, the fourth to
CPU 2, the fifth to CPU 4, the sixth through tenth to CPUs 6, 8, 10, 12,
and 14 respectively and then start assigning back from the beginning of
the list. GOMP_CPU_AFFINITY=0 binds all threads to CPU 0.
There is no libgomp library routine to determine whether a CPU affinity
specification is in effect. As a workaround, language-specific library
functions, e.g., getenv in C or GET_ENVIRONMENT_VARIABLE in
Fortran, may be used to query the setting of the GOMP_CPU_AFFINITY
environment variable. A defined CPU affinity on startup cannot be changed
or disabled during the runtime of the application.
If both GOMP_CPU_AFFINITY and OMP_PROC_BIND are set,
OMP_PROC_BIND has a higher precedence. If neither has been set and
OMP_PROC_BIND is unset, or when OMP_PROC_BIND is set to
FALSE, the host system will handle the assignment of threads to CPUs.