On 09/12/2012 15:00, Jeroen Mostert wrote:
[]
No, the service is definitely running continuously.
[]
Fair enough. I have no problem not getting a File -> Open menu from the
likes of gnuplot, but that's because that *only* has a command-line
interface so I expect no better. If something starts up with a GUI,
though, I expect to be able to use it without reading documentation.
Funny how that goes. :-)
[]
Provided it is named "peerstats.somethingsomething", right?
Unfortunately, the easy-to-find pages for troubleshooting NTP at
http://www.ntp.org/ntpfaq/NTP-s-trouble.htm arbitrarily rename the files
to "loops" and "peers", which is what I've been using (and other folks
too, I'd wager). I'm going to remove those options, but not just yet
(since I don't want to stitch files together).
The primary documentation for NTP is the set of HTML pages, not
"manpages".
Well, you're right.
http://www.eecis.udel.edu/~mills/ntp/html/confopt.html describes this
option, as well as the Meinberg docs (which are an earlier version). The
information seems to be "ungoogleable" in that you must read the whole
thing top to bottom before you know it exists, but that is of course no
excuse.
It is a shame that nothing *outside* the reference documentation (in
particular quick-start guides) seems to describe the use of this option,
though. It's also unfortunate that ntpd has been around so long (with
relatively few changes) that outdated documentation is a dime a dozen.
[]
I would figure this might fix things, but I'm holding off on that
because (as you say) this is not friendly on servers and would also not
fix/identify the root cause -- if my admittedly meager understanding of
how NTP works is correct, then it shouldn't be necessary to poll the
servers very frequently unless there's something inherently non-linearly
wrong with your clock.
[]
Nothing of the sort. It is a consumer PC used for everything, including
gaming, and although no gaming has been going on there could in theory
be some exotic driver or piece of software mucking things up in a
non-obvious way. If there is, though, I have no idea how to find it
other than through an extremely tedious bisection that's really not
worth it. If it turns out that NTP cannot work without stepping my clock
every so often, I can actually live with that. Not so much if it happens
on "real" machines, of course. This is strictly a research project.
It is worth reporting, however, that no stepping has been occurring
since I first reported the problem. This could be due to a simple
restart of ntpd and not through any options I've tinkered with. I've
tinkered with a *lot* of them, and since I'm not a professional
scientist, I have made no attempt at systematic analysis of all options
separately and combined, of course, just continued tweaking while I
wasn't satisfied :-)
I'm going to leave it alone for a bit to see the results after ntpd gets
some time to stabilize. For reference, I've done all of the following so
far:
- Upgraded to ntpd 4.2.7p310.
- Replaced individual "server" lines with a single "pool" line.
- Adjusted power management options within Windows to make processors
run at 100%.
- Updated the BIOS. (Also scratched my nose, which I expect has the same
effect.)
- Turned off explicit processor frequency stepping options in the BIOS.
- Used "bcdedit /set useplatformclock on" to force exclusive use of the
HPET (I'm guessing this does nothing at the moment since interpolation
isn't used).
- Last but not least, restarted ntpd.
Offset are still horrid (>30 ms) but I notice the drift is swinging up
too, so my guess is that ntpd hasn't fixed on a good value yet after all
the tinkering (and/or my clock is just bogus for reasons yet unknown).
If that doesn't work out, I may take apart the network traffic
(including the DSL router) to see if that has anything to do with
anything. Delay and jitter on the NTP packets seem fairly high (although
I don't know if that would explain continuous bad offsets).
NTO restarting - I meant a logical internal restart after a step, not
the service restarting.
I recall that the NTP Plotter is fairly open to accepting various
different file names automatically because, as you say, different places
have different recommendations. Sigh! Maybe I'll add a File|Open
dialog if the program starts with no file specified, but it's not top
priority at the moment.
Nothing describes "pool"? Well, my Windows set-up page (also referenced
by Meinberg) does for a start.
As I mentioned, I haven't tried Internet servers alone recently on
Windows except for one brief test with Windows-8 (because it has more
precise time routines):
http://www.satsignal.eu/ntp/Win-8+Internet.html
and I did a test with a Linux server, WAN-only as well:
http://www.satsignal.eu/ntp/2012-11-10-11-12-raspi1_ntp-b-day.png
If precise timekeeping is important, it may be worth upgrading to
Windows-8 (although I saw an improvement on only one of two PCs tested).
Re IPv6, I turn it off on all of my PCs as I don't use it either.
It may well be that 30 - 40 ms is the best you can expect without some
local server (e.g. FreeBSD/Linux/Win-8 box on your LAN), but stepping
every hour should not normally be happening.
--
Cheers,
David
Web: http://www.satsignal.eu
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