On 2012-12-10 22:54, unruh wrote:
On 2012-12-10, Jeroen Mostert<jmost...@xs4all.nl> wrote:
On 2012-12-10 22:18, David Woolley wrote:
Jeroen Mostert wrote:
For what it's worth, after all of that, the offset is steadily zigzagging
between 27 and 41 ms, which I'm guessing is about the best you can hope for on
a Windows machine with Internet sync. There have not been any major time step
adjustments.
Offsets should be scattered around zero. If they are all the same sign,
something is wrong.
OK. Well, that's too bad, I guess.
Throw me a bone here, fellas. It's nice to know something is wrong, but if all I
can see is that all peers consistently report offsets in this range, the best I
can conclude is that either ntpd simply isn't successful in disciplining the
clock appropriately, or there is some network problem going on that someone who
understands the NTP protocol could probably diagnose. That someone would not yet
be me.
If I offset the offsets (pardon my math) by -33 milliseconds, I'd roughly have a
zero axis that they'd be swinging around with a range of -10/+10. According to
unruh, even that would still be horrible in terms of accuracy, so I'm not sure
if that's fair in its simplicity.
Ah, if it really is 33 ms off on average, then yes something is wrong.
I assumed that you meant that the width of the scatter was 27-41ms, not
that the actual offset was always one sign and that far off.
However I do have to ask what this offset is.
What are your server entries in ntp.conf?
pool nl.pool.ntp.org iburst
Is this offset the offset from the same server that is being used to set the
time? Maybe a few lines from /var/log/ntp/peerstats.xxxxxxx would let us see
what the offset was doing. Or using some of the plotting programs to plot the
offsets measured from the varios servers.
ntpq -np:
remote refid st t when poll reach delay offset jitter
==============================================================================
nl.pool.ntp.org .POOL. 16 p - 64 0 0.000 0.000 0.977
*213.136.0.252 .PPS. 1 u 800 1024 377 18.958 35.896 10.670
+213.239.154.12 193.190.230.65 2 u 572 1024 377 18.924 35.018 8.883
+81.171.44.131 193.190.230.66 2 u 528 1024 377 18.855 34.990 7.952
+46.19.33.5 193.79.237.14 2 u 381 1024 377 17.953 35.253 8.111
+95.211.111.53 221.238.121.188 3 u 674 1024 377 18.924 35.641 8.806
+195.191.113.251 193.79.237.14 2 u 694 1024 377 19.920 34.866 7.075
+178.251.121.16 193.67.79.202 2 u 7 1024 377 18.956 33.863 8.940
-83.98.201.133 153.60.75.10 2 u 703 1024 377 17.986 33.285 7.294
+192.87.106.2 192.87.106.3 2 u 484 1024 377 17.853 32.520 6.394
peerstats tail of today (cutting off the first column to prevent wrapping):
77050.630 46.19.33.5 1424 0.032273618 0.018946933 0.016009420 0.005895699
77422.629 178.251.121.16 141a 0.034412494 0.018950946 0.016068324 0.009463505
77724.626 213.136.0.252 161a 0.035895776 0.018958086 0.016099349 0.010622052
77792.626 83.98.201.133 133a 0.035527840 0.018976950 0.016341863 0.009205395
77925.626 213.239.154.12 141a 0.031416422 0.017919850 0.020178597 0.006312898
77982.626 81.171.44.131 143a 0.031503337 0.018806412 0.020621400 0.005369126
78106.626 46.19.33.5 1424 0.035252534 0.017952556 0.016150506 0.008054216
78867.627 83.98.201.133 133a 0.033285314 0.017985677 0.016441743 0.007294158
78876.629 195.191.113.251 143a 0.034866163 0.019920461 0.016225952 0.007074704
78896.628 95.211.111.53 1424 0.035640734 0.018924019 0.020330239 0.008805813
78998.630 213.239.154.12 141a 0.035017893 0.018924218 0.020397573 0.008882811
79042.628 81.171.44.131 143a 0.034990054 0.018854869 0.020404077 0.007952290
79086.627 192.87.106.2 141a 0.032519558 0.017852997 0.016296482 0.006394490
79563.628 178.251.121.16 141a 0.033863486 0.018955711 0.020809018 0.008940402
As far as I can tell the peer offsets are OK, if you just ignore the fact that
they're all too high -- and stay that way.
--
J.
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