Since Linux kernel version 3.10, the function clock_gettime() now accept CLOCK_TAI. I didn’t manage to find a detailed description of this clock. What is its epoch ? EDIT 1: Just compared the output of CLOCK_REALTIME and CLOCK_TAI on my Linux 3.19 OS and it returns the exact same value (1442582497) !? Is CLOCK_REALTIME decremented at leap seconds ? EDIT 2: