https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92616
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #1) > I can reproduce it, but I think this has to be a glibc problem. Libstdc++ > simply calls clock_gettime(3), and both that and time(3) come from glibc. Correction, they come from the linux kernel's vDSO, not glibc. Apparently there are different paths for computing the seconds for time(3) and the CLOCK_REALTIME result. Either way, there's nothing we can do about it in libstdc++.