[LEAPSECS] Windows 10 time

[Brooks Harris]

On 2019-04-11 11:18 PM, Steve Allen wrote:
> As noted previously, Microsoft has improved timekeeping in Windows 10
For reference, two earlier blogs:

Leap Seconds for the IT Pro: What you need to know
https://techcommunity.microsoft.com/t5/Networking-Blog/Leap-Seconds-for-the-IT-Pro-What-you-need-to-know/ba-p/339811

Leap Seconds for the AppDev: What you should know
https://techcommunity.microsoft.com/t5/Networking-Blog/Leap-Seconds-for-the-AppDev-What-you-should-know/ba-p/339813

> and as of 2018-06-01 FILETIME is now TAI - 37 seconds instead of UTC.
Yes. Its "fixed epoch" since its activation on the given local system. A 
very significant change.
>
> Yesterday Dan Cuomo posted a blog entry
> https://techcommunity.microsoft.com/t5/Networking-Blog/How-NOT-to-test-the-Windows-Time-Service/ba-p/411592
> which has explicit apologies for how bad time once was on Microsoft
> and refers back to a February post
> https://techcommunity.microsoft.com/t5/Networking-Blog/Top-10-Networking-Features-in-Windows-Server-2019-10-Accurate/ba-p/339739
> which states that Microsoft will not smear (except, of course, when the
> system is configured to run the old way without leap seconds)
As I understand it legacy Windows didn't "smear" but stepped over the 
Leap Second like POSIX time does. I think they are just saying they are 
using this new system instead of smearing and systems configured to run 
in legacy mode will behave as before.
> with
> references to financial regulation agencies
I was at the ION PTTI meetings in January this year where Dan Cuomo et 
al presented. It was slick and convincing, and they were very 
forthcoming on the details of the system and their approach. They made 
it very clear it was the new financial regulations that was driving 
their efforts.

I also presented my work on accurate local time:
Accurate Local Timestamps Brooks Harris
https://www.ion.org/publications/abstract.cfm?articleID=16763
> and Matsakis, Levine, Lombardi
> at ION last year.
>
> I am impressed that Microsoft has managed to go somewhere that POSIX
> still refuses to go.
I agree MS has moved in the right direction. But it will be 
"interesting", as they say, since Windows time is no longer compliant 
with POSIX time and FILETIME timestamps will no longer match legacy 
Windows timestamps nor Unix time.

Hopefully Linux will follow suit in some manner. This might be 
accompanied with updating POSIX time in some manner to support Leap 
Seconds..

-Brooks
>
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