[arch-general] Leap seconds ntp and chrony?

Mauro Santos registo.mailling at gmail.com
Wed Jul 4 17:06:27 EDT 2012

On 04-07-2012 21:00, Tom Gundersen wrote:
> On Wed, Jul 4, 2012 at 9:06 PM, Kevin Chadwick <ma1l1ists at yahoo.co.uk> wrote:
>>> If you have a
>>> mercurial/git installation even in a small group, I am sure you'll prefer
>>> accurate timestamps in your commit history. And the list goes on...
>> I believe an RTC is perfectly capable of that.
> I tried to find some data on what to expect from RTC's. I was not very
> successful, except finding people citing 80-100PPM as typical drift
> rates (~8 secs/day).

>From data I have access to, taken from machines running ntpd, I can say
the following about the drift in PPM stored in ntpd's drift file:

my laptop: -9.699
machine 1: -8.762
machine 2: -443.266
machine 3: -35.417

Machine 1 is the newest and machine 3 is the oldest.

> Having a look at my own machine (a reasonably new Dell laptop) I don't
> see values quite that bad. I lose about 14 PPM, which amounts to
> roughly seven minutes in a year.
> Having that kind of discrepancies on a network doing distributed
> development would wreck absolute havoc.
> -t

Mauro Santos

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