News for hackers. Stuff that matters.

A comment on Keeping Time with Amazon Time Sync Service.

Re:Keeping Time with Amazon Time Sync Service by NelsonMinar on Wednesday November 29, 2017 @09:19PM (#15812919)
Details worth highlighting.. They recommend chrony over ntpd, which makes particular sense given that chrony is designed to work well on virtual machine. They are doing leap second smearing like Google does internally. They don't say anything about what sort of accuracy you can expect but if the clock source is truly local it could be very good.

It's kinda neat they're using a link local address.

[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by ams6110 on Wednesday November 29, 2017 @09:48PM (#15813066)
What is leap second smearing? Spreading it out over some other period, vs. a sudden jump of one second?
[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by sharth on Wednesday November 29, 2017 @10:26PM (#15813228)
https://developers.google.com/time/smear
[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by kuschkufan on Thursday November 30, 2017 @07:41AM (#15815275)
Would be interesting to use smearing for daylights saving time too. Make the hour twice as long when changing to winter and only take half the time when changing to summer.

In some scenarios handling DST might not be necessary then!

It wouldn't work for a tv schedule though, since what is broadcasted still uses actual time. ;)

[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by irhd on Wednesday November 29, 2017 @09:52PM (#15813085)
> Spreading it out over some other period

Yes.

They make a second last slightly long for some time period.

[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by zaxomi on Wednesday November 29, 2017 @11:54PM (#15813571)
Or shorter... Leap seconds can be negative.
[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by duskwuff on Thursday November 30, 2017 @12:20AM (#15813660)
Theoretically, yes, but it's never happened since leap seconds were established in 1972, and it seems very unlikely to happen for quite some time. Chances are that a lot of software doesn't actually support negative leap seconds at all.
[ Parent | on HN ]
Re:Keeping Time with Amazon Time Sync Service by a012 on Thursday November 30, 2017 @08:16AM (#15815429)
I setup a local chronyd server on AWS for long time, it's good that now I can use AWS local instead.
[ Parent | on HN ]