Meta wrote a blog about the difficulties in managing Leap Seconds, the process of adding seconds to UTC to align with Earth’s rotation, while advocating for the use of TAI (International Atomic Time) which does not incorporate Leap Seconds since 2017.
The challenge in managing Leap Seconds arises from the reliance on accurate timekeeping from atomic clocks in Stratum 0 satellites, while compensation is often handled on NTP servers at Stratum 2. The need to insert one second into a day poses issues as POSIX operating systems like Linux or macOS require days to have exactly 86,400 seconds, leading to the “smearing” of time increments to meet this requirement. This process adds complexity as NTP servers may either configure time smearing or not, resulting in time discrepancies on days with Leap Seconds.
Meta strives to create a nanosecond-accurate time comparison protocol, utilizing self-smearing through the fbclock library to insert 1 nanosecond every 62.5 microseconds. However, varying time discrepancies of up to 100 microseconds may still occur between servers using different techniques for time adjustments.
While international standards organizations aim to eliminate Leap Seconds by 2035, Meta supports this initiative by transitioning to TAI, eliminating Leap Seconds starting today.
TLDR: Meta discusses the challenges of managing Leap Seconds and advocates for the use of TAI to eliminate Leap Seconds for accurate timekeeping.
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