[ntp:questions] Ntpd accuracy

Eric Liu EricLiu at moxproducts.com
Wed Jun 8 06:41:29 UTC 2005


Hi all,

I am testing Nptd on office LAN. The server is my office PC(a dell computer,
P4 2.8G, 256M RAM, Windows 2000 sp4). Below is its ntp.conf:
----------------------------------------------------------------------
driftfile "C:\Program Files\NTP\etc\ntp.drift"
# local system clock
server 127.127.1.1
fudge 127.127.1.1 stratum 12
----------------------------------------------------------------------

The client is a PC104(586CPU) running embedded Linux. Below is its ntp.conf:
-----------------------------------------------------------------------
server	192.168.0.121 minpoll 4	# The dell computer is time server
driftfile /etc/ntp.drift
----------------------------------------------------------------------

Below are some data output by client Ntpd:
offset (s)               jitter
-0.000106       0.000836552
-0.0001345      0.00079245
 0.0001785      0.000786682
-0.0001575      0.000726
-0.0011095      0.000707
-0.0005755      0.0001365
-0.000439       0.000005
 0.004018       0.0032485
 0.005664       0.001646
 0.008183       0.002519
 0.0094615      0.0012785
 0.0114985      0.002037
 0.012597       0.0010985
 0.013009       0.000412
 0.011785       0.001224
 0.01082        0.000965
 0.0073825      0.002506541
 0.003579       0.002915856
 0.016884       0.001566162
 0.0151845      0.008989183
 0.004747       0.014612339
-0.023417       0.009749554
-0.019694       0.002824951
-0.012324       0.004500296

We can see that the offset varys in a very large range. How can I make the
offset much more regualr?  After our hard work, can I have 1ms accuracy?  If
there are many clients(in fact, there will), 1ms accuracy means among all
clients, relative to each other.

Thanks and regards
Eric




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