What does ntp_gettime returns if the connection has failed?
You can do the experiment yourself. Just unplug the ethernet cable.
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These are my opinions, not necessarily my employer's. I hate spam.
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It is de-rigueur to mention Linux and missing interrupts in the same
sentence. Even in the absence of evidence.
RedHat 7.2 shipped with IDE disks running with DMA disabled.
(I assumed that was a workaround for buggy hardware or a buggy driver.)
That was ok with light loads which covered most
It seems as if ntpd can't keep its clock syncronized. It's
drifting about 6-10 minutes per day, well over the 500 ppm limit.
After reading some of the posts on this newsgroup, I have come
to realize that debugging ntp problems can be quite complex.
Before I launch into a detailed search, I
In article [EMAIL PROTECTED],
Evandro Menezes [EMAIL PROTECTED] writes:
Many former participants of the NTP pool have stated that they
continue with lingering NTP clients after they left the pool.
The reason for this is that ntpd never tries to resolve an IP address
(assuming that *.pool.ntp.org
Unless I missed something, the RTC raises the IRQ when the fraction of a
second is 0.5 NOT when it is 0.
Or is something perhaps delaying the IRQ by 500 ms every time?
In other words, when I receive the IRQ, and the RTC tells me the date,
it is, in fact, 500 ms later than this date?
It sounds
The SHM driver is only useful if you have a helper program running
outside ntpd which writes to the SHared Memory segment.
Does anything other than gpsd write info to the SHM segment?
The (atomized) NMEA driver is the correct one to use with the GPS-18LVC.
I've lost track of PPS support in
Suppose a ntpd client can pick up 5 random pool servers, and
periodically (say once a day) replace the 'worst' server
by randomly picking a new one.
I like that suggestion. But, ignoring implementation details,
how do you decide which of two servers is better?
Is a server with 20 ms of jitter
The use of broadcast mode is important because it will allow the fixed
systems on the LAN to notice the laptop within ~ 64 seconds after it is
ready to be be a server.
Broadcast mode sounds like asking for troubles when you are plugged
into the net at the site you are visiting. It would be too
I like that suggestion. But, ignoring implementation details,
how do you decide which of two servers is better?
If one would get a '*' or '+' in ntpq peers output, and the other
would not, then it is better?
That tells you which is better right now. I was looking for
something that averaged
Therefore, whether I use the PIT or the LAPIC timer, ntpd will compute a
similar frequency offset (that of the crystal driving these two timers).
Right?
That's what I would expect.
If you are interested in this area, I suggest collecting and graphing
some data. Can you see any difference?
I'm totally confused by this series of snapshots below. Running 4.2.4p3
under NetBSD-3.1/patch, I started seeing some strange steps this morning.
I added some logging instructions in ntp.conf and restarted the daemon,
and the steps keep happening.
remote refid st t when poll
to synchronize time stamping in pharmaceutical enviromental it is possible
to connect all production machines via NTP to one Time Server.
Question is: Is there a procedure developped to validate that all
connected production machines do have the same time adjusted than the time
server? This
Here's what I want to do. I want to change the clock on my client
machine will automatically adjust when I change the clock on my server
machine. And I also want to record the statistics.
You are in the wrong place, then. ntpd has various defences against
machines that suddenly change their
Basically, what i need is how to add to the ntp.conf to record
statistics. Thanks
There is good documentation.
If you have the sources, it's (probably) in .../html/monopt.html
If not, google for clockstats peerstats and you should be
able to find a copy easily. (finding one that matches your
I see that nslookup resolves 1.us.pool.ntp.org into a list of IP
addresses. How does ntp deal with several IP addresses for a single
nerver name in ntp.conf?
It picks one and remembers it until you restart ntpd.
Most DNS servers deliver the set of addresses in random
order to distribute the
Does anyone know what the comparative GPS timing accuracies are in
precision and degraded modes?
http://www.leapsecond.com/pages/saoff/
http://www.niceties.com/atomic.html
My feeling is that even degraded would still be within the
microsecond.
The graphs in the above URLs used gear
Thanks for the clarification, and the hint with a CDMA-based solution.
Of course, ideally, I would try to have a stratum 1 clock available on
the LAN, avoiding the network to mess up my highly accurate time from
the reference clock. Actually this might be the only solution, as cell
phones might
Why not assigning a new driver number for PCI-SyncClock32 and add a
refclock_psc.c?
It's a minor pain to maintain a driver. If it's reasonable, it's
much simpler ovarall to make a single driver support several
versions of hardware.
My guess is that the hardware out on the board is pretty much
I believe NMEA is pretty much useless without a PPS signal.
NMEA works without a PPS. It just doesn't work as well as
people would like. I'd expect offsets in the tens of milliseconds
range rather than microseconds. I don't have any data to back that
up but I can get it if it will help.
The
In that case, I may need to use D cells or a power adapter for long-term
use.
The usual hack is to power it off one of the modem control signals.
It doesn't take much power. I'd add a regulator if I couldn't find
the specs on the chip.
--
These are my opinions, not necessarily my employer's.
Suppose I build something like that. Is there anything I should
tinker with to tell ntpd that it has a (very) stable local clock?
fudge 127.127.1.0 stratum 1. (-:
In fact, isn't this how stratum 0s are born?
That's not the case I was interested in.
I was thinking about a PC that had a clock
According to https://buy.garmin.com/shop/shop.do?pID=223pvID=796, it
says that the receiver has an integrated magnetic base.
I had never noticed the magnet. Being curious, I tried
it with a handy knife. Yes, there is a magnet there.
Even if it doesn't, Richard's solution of some glue and a
On a related note, I've read the following:
http://en.wikipedia.org/wiki/Crystal_oscillator
Care must be taken to use only one crystal oscillator source when
designing circuits to avoid subtle failure modes of metastability in
electronics. If this is not possible, the number of distinct
Upgrading and Repairing PCs, 17th Edition states:
A crystal oscillator controls clock speeds using a sliver of quartz
sometimes contained in what looks like a small tin container. Newer
systems include the oscillator circuitry in the motherboard chipset, so
it might not be a visible separate
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