https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114765
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Stijn De Weirdt from comment #2) > apologies for my ignorance, but how is working as expected? i can't make > this up from the description of the variable; and it's unexpected since > there is no openmp code being run (naively then; clearly libgomp does > something). libgomp has library constructors which already do something. > we have an environment where we set OMP_PROC_BIND=true because openmp code > clearly benefits from it; but it also affects code where libgomp is simply > linked to it, but nothing else is done with it. See the OpenMP standard. By using that env variable (or similar), you request that the initial thread binds to a certain CPU/thread (the OMP_PROC_BIND=true case is less specified than when using say OMP_PLACES and exact rules which thread binds to which place).