Date: Wed, 20 Jul 2005 18:45:51 -0400 From: Garance A Drosihn <drosih@rpi.edu> To: "Joshua Coombs" <jcoombs@gwi.net>, <freebsd-ppc@freebsd.org> Subject: Re: Minor issues of time on PPC Message-ID: <p0623095ebf0475e8eaca@[128.113.24.47]> In-Reply-To: <0cbd01c58c60$246dc590$1700a8c0@failure> References: <p0623094fbf02347491f0@[128.113.24.47]> <0cbd01c58c60$246dc590$1700a8c0@failure>
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At 8:48 AM -0400 7/19/05, Joshua Coombs wrote:
>"Garance A Drosihn" <drosih@rpi.edu> writes:
>
>>I've noticed a few minor issues with tracking the present time
>>on my Mac-mini.
> <snip>
>>Hmm. I just noticed that
>>ntpd is running with '-f /var/db/ntpd.drift' -- but that file does
>>not exist. But then, it doesn't exist on my other freebsd machines,
>>and they all seem to keep accurate time. Still, I'm going to try
>>creating that file and see if it does any good.
>
>echo 0 > /var/db/ntpd.drift
>restart ntpd
I did these.
>Try this, let the machine run for a couple hours, then email the
>output of:
>
>ntpdc -c loopinfo
>ntpdc -c kerninfo
>ntpq -p
It's been running about 30 hours now (I forgot about it last night),
and time on the Mac-mini is now off by a little more than five
minutes. Here's the output:
(33) # ntpdc -c loopinfo
offset: 0.000000 s
frequency: 0.000 ppm
poll adjust: 0
watchdog timer: 106387 s
(34) # ntpdc -c kerninfo
pll offset: 0 s
pll frequency: 0.000 ppm
maximum error: 53.197 s
estimated error: 1.6e-05 s
status: 2001 pll nano
pll time constant: 0
precision: 1e-09 s
frequency tolerance: 496 ppm
(35) ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
columbia. 128.59.59.177 3 u 864 1024 377 1.275 302122. 2934.24
enterprise. 130.207.244.240 2 u 875 1024 373 7.396 302088. 2934.08
A few interesting points here. For one, here is ntpd -p from my
i386 box (which has been running with only one ntp server), after
that box has been running for almost three days:
(50) # ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
*columbia. 128.59.59.177 3 u 134 1024 377 1.965 -0.540 0.133
My two FreeBSD machines are on the same 100-Mbit switch in my office,
so I wouldn't expect them to come up with such dramatically different
values of offset and jitter when talking to columbia...
Also, the value inside /var/db/ntpd.drift does not seem to change,
neither on my powerPC machine or my i386 box. (although I just
created it on the i386 box, so maybe ntpd hasn't run long enough
on that one).
I stopped ntpd and started it again, and it didn't seem to do much
of anything wrt changing the time. I stopped it again, and started
ntpdate instead, and that updated the time correctly. After doing
that, I then restarted ntpd again. I ran the queue cmd immediately
after restarting ntpd, and it said:
(52) # ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
columbia. 128.59.59.177 3 u 13 64 1 1.321 36.700 0.001
enterprise. 129.6.15.29 2 u 12 64 1 1.178 39.601 0.001
I checked a few other things, and entered the command five or ten
minutes later, and it now says:
(53) # ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
columbia. 128.59.59.177 3 u 57 64 3 1.262 216.989 180.289
enterprise. 130.207.244.240 2 u 53 64 3 1.143 228.484 188.883
It seems the offset and jitter are rapidly increasing.
Hmm. It might be interesting to try the ntpd client that Matt wrote
for Dragonfly, and see how well that works. That's much simpler code,
and would probably be good enough for my purposes. Maybe if I have
some time this weekend, I'll try that.
--
Garance Alistair Drosehn = gad@gilead.netel.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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