Thanks for the interesting link, good to know! So we are in fact, pretty close to a monotonically-increasing, TAI-like Unix clock. The original article said,

Thanks for the interesting link, good to know! So we are in fact, pretty close to a monotonically-increasing, TAI-like Unix clock. The original article said, > Each Unix day has the same number of seconds, so it can’t just add an extra second – instead, it repeats the Unix timestamps for the last second of the day. Your POSIX link says, > As represented in seconds since the Epoch, each and every day shall be accounted for by exactly 86400 seconds. I'm not a expert on timekeeping, but it appears the only problem here is that the Unix time is bounded by a 86,400-second day, which I guess was meant to make a Unix day predictable, so we still have to double count or skip seconds. It seems the only thing we need to make Unix time monotonic is simply removing the 86,400 seconds Unix day from specification. On the other hand, it means a Unix day would be unpredictable and it would be impossible to calculate a Unix time without a database, and difficult calculate future Unix time using calendar time. So TAI doesn't automatically solve every problem, everything comes with a tradeoff. But I think a unpredictable Unix day should be fine for purpose of an internal system clock, so perhaps it's still not a bad idea.