[LEAPSECS] Google, Amazon, now Microsoft
phk at phk.freebsd.dk
Tue Jun 2 16:25:58 EDT 2015
In message <556D8C59.9040309 at edlmax.com>, Brooks Harris writes:
>> A lot of Windows machines are doing things where you would expect
>> people to care about leap-seconds: Nuclear power plants control
>> systems, Air Traffic Control computers, Surgery robots, Patient
>> Monitors, Power grid disturbance detectors etc. etc. etc.
>In many of those uses the PC is not doing the mission critical timing.
>No event-driven multitasking OS can do precise timing [...]
You're saying this to the bloke who implemented a prototype adaptive
optics solution for the ESO ELT on a plain, unmodified FreeBSD
Anyway, the PC doesn't need to do the RT parts directly in order
to mess them up with wrong timestamps.
>> But this is not something they are happy about doing, much less
>> proud of doing, but weighing the risks of "heterogeneous" leap-second
>> handling and the risk of being up to half a second wrong about time
>> for most of a day, they picked the second risk.
>The failures folks are frightened of are bugs evoked by the Leap Second.
>At least some of which are just "stupid" bugs, like threading races when
>outputting the Leap Second event to the system log, not basic
>timekeeping calculation errors. If all parts of the system did POSIX and
>NTP correctly the timekeeping would not reflect UTC correctly because
>neither POSIX or NTP do that anyway, but the systems wouldn't hang or
>crash. As it is they have to "smear" to minimize the problems.
Which is like saying that if only 50% of all programmers weren't
below the skill-median, we wouldn't have the problem.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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