On Sep 16, 2007, at 11:03 AM, Chuck wrote:
> does anyone have a spec on the average duration time an active time
> request /
> response lasts? we are trying to find connection states of 1 in /
> proc/net/udp
> and find it almost impossible.
A typical NTP request/response happens in less (much less?) than 1ms
if you're doing queries to localhost, and even queries to other
timeservers on the same local switched subnet tend to have latencies
of 0.2 - 0.3 ms. Otherwise, the network round-trip latency is going
to dominate.
--
-Chuck
PS: If you'd like to know how to measure this, try "ntpdate -d" or
"ntpq -p":
41-ns1# ntpdate -d localhost
17 Sep 13:14:28 ntpdate[62347]: ntpdate [EMAIL PROTECTED] Fri Sep 14
19:54:16 GMT 2007 (1)
Looking for host localhost and service ntp
host found : localhost
transmit(127.0.0.1)
receive(127.0.0.1)
transmit(127.0.0.1)
receive(127.0.0.1)
transmit(127.0.0.1)
receive(127.0.0.1)
transmit(127.0.0.1)
receive(127.0.0.1)
transmit(127.0.0.1)
server 127.0.0.1, port 123
stratum 2, precision -18, leap 00, trust 000
refid [127.0.0.1], delay 0.02580, dispersion 0.00000
transmitted 4, in filter 4
reference time: ca9933bc.1b89fc92 Mon, Sep 17 2007 13:11:24.107
originate timestamp: ca993474.8e1878e2 Mon, Sep 17 2007 13:14:28.555
transmit timestamp: ca993474.8e0d96db Mon, Sep 17 2007 13:14:28.554
filter delay: 0.02583 0.02582 0.02580 0.02580
0.00000 0.00000 0.00000 0.00000
filter offset: -0.00000 -0.00001 -0.00000 0.000007
0.000000 0.000000 0.000000 0.000000
delay 0.02580, dispersion 0.00000
offset -0.000003
17 Sep 13:14:28 ntpdate[62347]: adjust time server 127.0.0.1 offset
-0.000003 sec
42-ns1# ntpq -p
remote refid st t when poll reach delay
offset jitter
========================================================================
======
LOCAL(1) .LOCL. 10 l 6 64 377 0.000
0.000 0.004
+timekeeper.isi. .GPS. 1 u 178 512 373 96.569
4.535 4.901
*nist1-ny.witime .ACTS. 1 u 209 512 377 14.222
0.007 0.117
-clock.isc.org 216.200.141.8 2 u 197 512 367 85.034
-3.226 0.200
+clock2.redhat.c .CDMA. 1 u 126 512 377 46.081
-6.363 0.671
-pi.codefab.com 18.26.4.105 2 u 237 512 177 0.225
-2.984 0.054
-shot.codefab.co 65.212.71.102 2 u 141 512 377 0.265
-3.782 0.595
-pong.codefab.co 209.51.161.238 2 u 44 512 377 0.270
-0.463 1.580
The last three machines are all configured as NTP peers, and are
showing about a quarter of a millisecond delay...
_______________________________________________
timekeepers mailing list
[email protected]
https://fortytwo.ch/mailman/cgi-bin/listinfo/timekeepers
