Date: Wed, 27 Dec 1995 16:03:05 -0500 From: "Garrett A. Wollman" <wollman@lcs.mit.edu> To: peter@haywire.dialix.com (Peter Wemm) Cc: freebsd-current@freebsd.org Subject: Re: Tick, tock, adjust the clock Message-ID: <9512272103.AA17279@halloran-eldar.lcs.mit.edu> In-Reply-To: <4bqdc4$8h2$1@haywire.DIALix.COM> References: <199512261708.LAA14134@miller.cs.uwm.edu> <4bqdc4$8h2$1@haywire.DIALix.COM>
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<<On 27 Dec 1995 11:08:52 +0800, peter@haywire.dialix.com (Peter Wemm) said:
> I've had the same problem for quite some time.. On all the
> FreeBSD machines I have access to, the xntpd oscilates very very badly
> (like you've shown) and eventually logs "not logging any more time
> steps" or something like that.
I'm curious to know whether the clock speed is correctly diagnosed on
these machines... This sounds like the sort of thing I would expect
to happen if the clock-speed-diagnosis code doesn't come up with an
answer that's reasonably close. My 60-MHz machine is diagnosed as
59.99-MHz, and xntpd reports its frequency error as about 7.6 seconds
per day.
You might try making i586_ctr_rate tunable via sysctl(8), and fiddling
the value a little bit to see if you can come up with something more
correct. That would be a very good feature to have, and I may get
around to adding it sometime soon since PHK's sysctl is able to deal
with variables that are only conditionally defined in a reasonable
way. (It's a fixed-point number with I586_CTR_RATE_SHIFT bits of
fractional precision.)
> The really depressing part, is the SVR4 machines (you know, the ones
> with the horrible 10ms clock resolution) sitting right next to the
> FreeBSD machines with their super-high-res clocks are locking right in
> and staying very stable (xntpd getting to 1024 poll and very low
> dispersion), while the FreeBSD machines are constantly wobbling all
> over the place. :-(
My machine looks like this:
remote refid st t when poll reach delay offset disp
==============================================================================
+catfish.lcs.mit rackety.udel.ed 2 u 294 1024 357 2.24 5.002 1.25
+amsterdam.lcs.m ncar.ucar.edu 2 u 540 1024 377 2.09 5.686 4.17
eiffel.lcs.mit. tock.usno.navy. 2 - 38m 512 0 2.93 3.993 16000.0
pepper.lcs.mit. catfish.lcs.mit 3 u 654 1024 377 4.50 5.002 1.46
*pooch.osf.org .WWV. 1 u 69 1024 377 10.24 4.069 4.06
halloran-eldar. catfish.lcs.mit 3 u 815 512 324 3.97 6.322 4.65
hergotha.lcs.mi catfish.lcs.mit 3 u 417 1024 252 0.87 4.868 7.98
NTP.MCAST.NET 0.0.0.0 16 u - 64 0 0.00 0.000 16000.0
-GAWollman
--
Garrett A. Wollman | Shashish is simple, it's discreet, it's brief. ...
wollman@lcs.mit.edu | Shashish is the bonding of hearts in spite of distance.
Opinions not those of| It is a bond more powerful than absence. We like people
MIT, LCS, ANA, or NSA| who like Shashish. - Claude McKenzie + Florent Vollant
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