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What are expected values for offset and jitter from NTP?

I have Solaris 11.4 in a VM with NTP configured and am comparing Solaris time stats to my Mac. I notice that MacOS sntp -sS time.apple.com reports very low offset of ~0.01s +/- ~0.01s. On Solaris I invoke ntpq -pcrv and note my offset is ~-6s +/- ~2s to time.nist.gov.

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ntpd expects to be able to tune a fairly consistent clock to run as closely as possible to a reference clock. Although startup will usually try to sync pretty close, it may spend a long time analyzing drift rather than resetting and trying to keep it close.

I would expect an OS running inside a VM with no special clock tools to be significantly worse than one running on hardware. NTP may have difficulty converging.

If the clock is fully emulated, the frequency it ticks may change as CPU load changes. If the VM clock is periodically forced from the host clock, NTP may be confused by the discontinuous jumps.

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    really depends on the virtualization, but yes, virtualizers usually don't hand down control access to the hardware clock (for obvious reasons), so there's a layer of software in between that'd memorize the distance between what the VM said the clock should be set and the system clock Commented Jul 14 at 10:42
  • Chrony has a Solaris port chrony-project.org/news.html - It's the standard at AWS and financial institutions like it for how it handles the spread for leap seconds ntp.org/documentation/4.2.8-series/leap Commented Jul 16 at 11:09

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