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Date: Tue, 16 Jul 1996 10:00:03 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199607160000.KAA24680@godzilla.zeta.org.au>
To: dwhite@resnet.uoregon.edu, sthaug@nethelp.no
Subject: Re: xntpd stepping clock backwards? (was: Re: NFSv3 fixes for review)
Cc: bde@zeta.org.au, current@FreeBSD.ORG
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>> > xntpd only does tiny adjustments which can't possibly make the clock
>> > go backwards.  OTOH, ntpdate or ordinary `date' can set the clock back
>> > by years.
>> 
>> Then why does my syslog show the following? It sure looks to me like xntpd
>> sometimes steps the clock backwards. This is on 2.2-960612-SNAP.

>I think you are misinterpeting the log entry.  xtnpd works by adjusting 
>the length of a 'tick' so the clock 'speeds up' or 'slows down' as 
>necessary.  This adjustment is called 'slew' and is inserted in very, 
>very small increments.  But time continues to move forward, even if it 
>means slewing the ticks for quite a while.

That's what I thought.  Unfortunately, xntpd really does step the clock
in some cases, unless SLEWALWAYS is defined.

Bruce