Date: Tue, 21 Apr 2009 20:57:59 +0200 From: Mel Flynn <mel.flynn+fbsd.questions@mailing.thruhere.net> To: freebsd-questions@freebsd.org Subject: Re: Preventing ntpd from adjusting time (backwards) Message-ID: <200904212057.59535.mel.flynn%2Bfbsd.questions@mailing.thruhere.net> In-Reply-To: <C397BD04-8E91-4849-BB8F-A2034F10C18E@mac.com> References: <200904211106.01965.mel.flynn%2Bfbsd.questions@mailing.thruhere.net> <C397BD04-8E91-4849-BB8F-A2034F10C18E@mac.com>
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On Tuesday 21 April 2009 19:43:30 Chuck Swiger wrote: > Hi, Mel-- > > On Apr 21, 2009, at 2:06 AM, Mel Flynn wrote: > > Some coarse reading of ntpd(8) and ntp.conf(5) doesn't lead me to > > believe it's > > possible to make ntpd *not* adjust the time. With adjust I don't > > mean the skew > > operation, but really change the time. > > Perhaps I've missed it elsewhere in this thread, but I don't believe > anyone actually answered the original question, which would be to use: > > -x, --slew > Slew up to 600 seconds. > > Normally, the time is slewed if the offset is less than the > step > threshold, which is 128 ms by default, and stepped if > above the > threshold. This option sets the threshold to 600 s, > which is > well within the accuracy window to set the clock > manually. Hmm, that might work. Thanks! > It should be surprising that your clock would jump by 6 seconds. Do > you have adequate upstream timesources (ie, at least 4) configured, is > your local HW clock busted somehow, or are you doing something odd > with power-savings mode or running in a VM or something...? One timesource, shared on local network, this machine is a client of the gateway, which uses only one source (ntp.alaska.edu, which is geographically 10 minutes by car but thanks to Alaska bad peering, we go through Seattle anyway). I checked the logs, that machine didn't step at all that day (or any other day, as far as my logs go). It always happens after reboot, as Matthew indicated. No VM, no power-savings. The only odd things are Hyperthreading and the reboot. Well, I abuse the machine quite heavily from time to time, but then I'd expect the clock to be slow, not 6 seconds faster. -- Mel
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