[LEAPSECS] Google, Amazon, now Microsoft

Brooks Harris brooks at edlmax.com
Sun May 31 16:54:06 EDT 2015

Hi Poul-Henning,

On 2015-05-31 03:33 PM, Poul-Henning Kamp wrote:
> --------
> In message <556B5D76.6000202 at edlmax.com>, Brooks Harris writes:
>>> Most Windows boxes don't run NTP.
>> I don't think that's true. As far as I know, Windows, either personal or
>> Server versions, synchronize using NTP, and did so with SNTP until Win
>> 2000, then NTPV3, then NTPV4. I glean this from accumulated knowledge -
>> its difficult to find authoritative information from Microsoft about it.
> So that depends what you mean by "NTP".
> If you mean that your packets look like NTP packets, then yes, it does
> run NTP.
> But I mean "use the NTP clock model".
Right. OK, well, its not made clear exactly what it does with its 
counting over the Leap Second (like NTP "freeze" or POSIX "reset") or 
how its applied to local timescales. .
>> On my personal laptop running Win 7, I don't have Active Directory, and
>> the W32Time service is *not* started. But it will synchronize via the
>> usual desktop "Internet Time" mechanisms. It uses either
>> "time.nist.gov", "time.windows.com", etc. These are NTP servers.
> But what happens when the leap-second hits ?
> Most likely, at some random time after the leapsecond, your clock
> steps a second.
Right, for normal personal computers. Severs may be more tightly synched.
>> Windows of any version is fundamentally following NTP.
> Not even close.
Well, what I mean its it relies on NTP for its time in some way or 
other. I didn't mean it *is* NTP, so I'll retract the comment in that form.
> That's why Meinberg still maintains their NTPD client.
Right. The discussion didn't start out about accuracy, but about the 
counting rules.
> You should find Martins presentation from FOSDEM about this.
>> But that doesn't answer the first question about how the Leap Second is
>> applied to local time by Azure and/or Windows.
> Because that is the only sane thing for them to do, given the (broken)
> timekeeping in the software they run.
Well, broken in what way for what purpose? An awful lot of people use 
it.. Its time is not "precise" and/or "accurate" without some help from 
somewhere, but its good enough to have become the largest platform. I 
could write a three volume tome on "Why I Hate Windows". But its the 
environment, like it or not.
> The fundamental question about leapseconds is not about where Rob can
> find the sun at noon, but about teaching an awful lot of rather crap
> programmers how to cope with a infrequent and intractable complexity
> on short notice.
I don't think its fair to insult all the programmers. Timekeeping is a 
specialty, and a controversial specialty. Most programmers are trying to 
use system timekeeping services on various platforms and applications 
that are not well documented, and often flawed. The fact there are bugs 
is no surprise and until a concerted effort is made to improve the 
underlying standards and implementations it will be a trash..
> It seems like Daniels scheduling on this one may show us which is more
> important.
Sorry, lost track of what that comment refers to..


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