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F-ckin Leap Seconds, how do they work?
On (2012-07-03 19:33 +0100), Nick Hilliard wrote:
> Google's approach to this is interesting:
>
> > http://googleblog.blogspot.ie/2011/09/time-technology-and-leaping-seconds.html
Yes. I'm sure this is good enough for most people, most people don't need
precise time but virtually everyone needs monotonic time.
And this is easy to deploy TAI + UTC presentation using leapsecond file
lookup isn't exactly easy.
Too bad this isn't standard configuration option in NTPd.
Also one thing I wonder, why did GOOG choose to skew in just 24h, why not
the moment leap is announced? Everyone has some accuracy budget, what ever
that might be, it almost certainly is same every day. So you could live
with tighter accuracy budget the longer you spend skewing.
PC clock on average is probably like 15PPM accurate (or order magnitude of
worse, IBM servers seem to be exception). If you'd skew 3 months, your
skewing would cause inaccuracy of 0.19PPM. Skewing in single day causes
inaccuracy of 11.6PPM (still almost certainly better than free-running PC
oscillator)
--
++ytti
- References:
- F-ckin Leap Seconds, how do they work?
- From: gbonser at seven.com (George Bonser)
- F-ckin Leap Seconds, how do they work?
- From: nanog at armoredpackets.com (AP NANOG)
- F-ckin Leap Seconds, how do they work?
- From: smb at cs.columbia.edu (Steven Bellovin)
- F-ckin Leap Seconds, how do they work?
- From: wolfgang.rupprecht at gmail.com (Wolfgang S. Rupprecht)
- F-ckin Leap Seconds, how do they work?
- From: saku at ytti.fi (Saku Ytti)
- F-ckin Leap Seconds, how do they work?
- From: valdis.kletnieks at vt.edu (valdis.kletnieks at vt.edu)
- F-ckin Leap Seconds, how do they work?
- From: saku at ytti.fi (Saku Ytti)
- F-ckin Leap Seconds, how do they work?
- From: owen at delong.com (Owen DeLong)
- F-ckin Leap Seconds, how do they work?
- From: saku at ytti.fi (Saku Ytti)
- F-ckin Leap Seconds, how do they work?
- From: nick at foobar.org (Nick Hilliard)