[LEAPSECS] Hetzner mail to customers: 1 megawatt more power due to leap second

Michael Spacefalcon msokolov at ivan.Harhan.ORG
Thu Jul 5 13:57:55 EDT 2012


Warner Losh <imp at bsdimp.com> wrote:


> I think this was more of a comment about how fragile our modern

> infrastructure is when confronted with a Leap Second.


Yes, I agree that the evidence points in the direction of your
statement. But we probably disagree on what the right solution is.
Per my religion, Leap Seconds are in the right and that stupid modern
infrastructure is in the wrong. Therefore, instead of getting rid of
the former, get rid of the latter.


> Bugs that existed in the system for years weren't fully deployed in time for

> the leap second. The result was what was outlined in the story. Bugs that

> would have been trivial to identify had any testing actually been done, I

> might add. And not only one bug, but 6 different, or interrelated bugs to

> boot. People didn't take the leap second seriously, since it is only a

> second after all, so many people did understand the problems well enough and

> made the decision not to deploy. Many others never heard of the problem

> because it is just a leap second after all, so didn't get much attention....


I see the problem as having a different root cause. Leap seconds are
good for one and only one thing: radio broadcast time signals that
transmit a pulse per SI second. *NO* other system should ever be
exposed to leap seconds directly, i.e., leap seconds should be
rubberized before being presented to systems (such as real-number JD
and MJD scientific time notations, or UNIX/POSIX time) that see time
as a scalar rather than broken-down HH:MM:SS.

What NTP and POSIX-pandering versions of Unix/Linux do nowadays
(stepping the time backward and repeating a second) *is* the root
cause of all of the "leap second" problems: it is an assininely stupid
and wrong solution, and no amount of bugfixing or testing will ever
fix it, until the root cause is eliminated.

Contrast it with a sensible solution like Google's leap smear or the
UTC-SLS proposal. The inherent instability (unpredictable frequency
variation) of a normal computer motherboard quartz crystal oscillator
is far greater than the difference in rate between physics-time and
Earth-rotation-time, hence if one were to use an NTP-like scheme to
steer computer clocks to the latter instead of the former, they will
never know the difference. Unlike UTC, GMT (or any other longitude's
Mean Solar Time for that matter) does not have leap seconds or any
other stupid aberrations. But GMT is not directly observable and is
not available in real time for NTP-like steering, hence we need a
synthetic timescale that is synthesized from broadcast atomic time,
but behaves like GMT, i.e., is rubbery rather than leapy. A
standardized, widely recognized and adopted scheme for converting
leap seconds to rubber seconds is what we need.

SF


More information about the LEAPSECS mailing list