Google's proposal is a smear. [1] Most time servers do not use smear. No idea what behavior it may introduce in places where sub-second time is important. Curious if all these bugs [2] were fixed specifically to deal with going backwards.
The brilliant thing about the smear is that it distributes the new second across each second of the day, so that each second differed by 1/86400 seconds, well within the margin of error for NTP.
As far as the computers were concerned, nothing was different.
The less brilliant thing about the smear is that if your ntpd syncs from smeared and unsmeared servers, the results aren't great.
It would have been better if they would have kept the time on the wire accurate or added mandatory protocol stuff to avoid confusing things for ntpds configured to different leap second handling.
I don't think we can predict ahead of time whether we'll need a leap second or not
If the question is "why bother syncing time to Earth's orbit around the sun at all", I don't have a good answer for that except at this point, it's tradition.
Systems are absolutely not ready. Leap seconds are a bad idea and negative leap seconds are worse. Just don't do it and let the drift cancel out.
negative leap seconds aren't too bad. jumping forward a second won't lead to a time loop like jumping back did on several systems (some twice!)
NTP.
By any other standard, most manually set clocks are up to a full minute off all the time.
Yeah, but we're thinking of systems where nanoseconds matter.
MiFID 2 alone forces sub-μs precision. Million times less than the leap 1 second.
NTP minute away is good for displaying date on the workstation, not for many of the devices that are critical to the modern world.
dont most systems that rely on sharp timing simply manage it themselves.
Yesno.
Sure they have their own time servers fed from the GPS, but they need to be _accurate_ in relation to the world.
But timestamps used by companies forced to use very accurate timing must be synchronised to UTC.
Google's proposal is a smear. [1] Most time servers do not use smear. No idea what behavior it may introduce in places where sub-second time is important. Curious if all these bugs [2] were fixed specifically to deal with going backwards.
[1] - https://developers.google.com/time/smear
[2] - https://rivassec.com/leap-second-chaos-2012.html
The brilliant thing about the smear is that it distributes the new second across each second of the day, so that each second differed by 1/86400 seconds, well within the margin of error for NTP.
As far as the computers were concerned, nothing was different.
The less brilliant thing about the smear is that if your ntpd syncs from smeared and unsmeared servers, the results aren't great.
It would have been better if they would have kept the time on the wire accurate or added mandatory protocol stuff to avoid confusing things for ntpds configured to different leap second handling.
If we have positive and negative leap seconds, why are we doing anything at all? 1 second forward, just to go 1 second back 10 years later…
I don't think we can predict ahead of time whether we'll need a leap second or not
If the question is "why bother syncing time to Earth's orbit around the sun at all", I don't have a good answer for that except at this point, it's tradition.