[ntp:questions] Time going backwards
Richard B. Gilbert
rgilbert88 at comcast.net
Thu Aug 14 03:03:59 UTC 2008
John Bartas wrote:
> Hi Folks,
> I have some questions about when (if ever) NTP will set time backward.
> I'll be using it on Embedded Linux for time stamping video frames.
> I've found several mentions in RFC 1305 that this should not happen, and
> also in section "Step Phase Adjustments" mention that it can jump
> Is there a simple description anywhere if what variables affect this,
> and how? I'd like to know when it's going to jump backwards on Linux -
> what the rules are and what control I have over it.
> Any help would be appreciated.
I wouldn't get terribly upset about it. Ntpd does not step the time
unless it is grossly wrong. Ntpd has been known to step *FORWARD* on
certain Windows and MAYBE Linux systems when heavy disk activity
resulted in missed clock ticks. I can't think of anything likely to go
wrong that would cause a *BACKWARD* step.
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