Can anyone give me a hint to understanding this difference between root dispersion, as reported by the production version, and the dev version, of ntpd?
My test machine has a very stable oscillator, and a good PPS source. configuration is below: a PPS source, gpsd though SHM, and a local server. When running the production (4.2.6p5) ntpd, I see root dispersion settle to a handful of microseconds. It increments at the dispersion (15us/s), as documented, until pulled back down on the next update. When running the DEV ntpd, root dispersion is pulled down to 1000us, and increments at 15us/s. No matter what, rootdisp does not go below 1ms. [root@n1g ntpq]# ./ntpq -crv associd=0 status=011d leap_none, sync_pps, 1 event, kern, version="ntpd [email protected] Sat Jan 28 11:01:39 UTC 2012 (1)", processor="x86_64", system="Linux/3.1.8-2.fc16.x86_64", leap=00, stratum=1, precision=-23, rootdelay=0.000, rootdisp=1.000, refid=PPS, reftime=d2ceed35.e7967bf1 Sat, Jan 28 2012 21:55:01.904, clock=d2ceed38.1b41ac47 Sat, Jan 28 2012 21:55:04.106, peer=60158, tc=3, mintc=3, offset=-0.000, frequency=38.361, sys_jitter=0.001, clk_jitter=0.000, clk_wander=0.000, tai=34, leapsec=201207010000, expire=201212280000 Is this by design, or an oops? I stumbled upon it and though 'this might not be right'. The machine is 217.198.219.99 / 2002:d9c6:d896:ff05:21c:c4ff:fe10:7ba. /Kasper Pedersen ------------------ driftfile /var/lib/ntp/drift restrict default nomodify notrap nopeer restrict -6 default nomodify notrap nopeer restrict 127.0.0.1 restrict -6 ::1 tos minsane 0 #the PPS source is 14 usec late compared to UTC. By design. server 127.127.22.0 minpoll 3 maxpoll 3 fudge 127.127.22.0 flag2 0 flag3 1 time1 0.000014 #gpsd through SHM server 127.127.28.1 minpoll 3 maxpoll 3 prefer true iburst fudge 127.127.28.1 refid GPS time1 0.000044 server 192.168.9.3 minpoll 3 maxpoll 3 iburst crypto digest sha1 host n1g ident n1g pw n1g keysdir /etc/ntp/ includefile /etc/ntp/crypto/pw keys /etc/ntp/keys statistics clockstats loopstats peerstats statsdir /var/log/ntpstats/ leapfile /etc/ntp/leap-seconds.3535228800 ------------------------ _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
