> -----Original Message----- > From: Charles Swiger [mailto:cswi...@mac.com] > Sent: Friday, May 24, 2013 1:01 AM > To: Mischanko, Edward T > Cc: questions@lists.ntp.org > Subject: Re: [ntp:questions] Tighter regulation? > > On May 23, 2013, at 10:02 PM, "Mischanko, Edward T" > <edward.mischa...@arcelormittal.com> wrote: > > It takes too long to figure out it needs a more aggressive correction. > > If I leave maxpoll at the default of 1024 seconds, my clock drifts > outside > > of 5 milliseconds consistently. > [Mischanko, Edward T]
Measured by the best time sources I have available. I am saying that my clock will drift to 5 milliseconds at maxpoll 10 and polling does not decrease to a level that will bring my clock back to an offset of +/- 1 millisecond. > Measured by what? If you have a better source of time available, sync > ntpd using that. > > More importantly, ntpd should be entirely able to compensate for a steady > drift of ~50 ppm; > are you saying that not only do you have a long-term drift, but short-term > instability > which varies by ~50+ ppm hour-by-hour? > > > Too much assumption is made that everyone will have the perfect computer > and > > the perfect network when configuring these various filters. What works > on > > the blackboard does not always work in reality. > [Mischanko, Edward T] I your 25 year experience have you ever thought they may be a better way to achieve the same goals? Or, have you ever looked at your goals and asked yourself what are the primary goals and what are secondary goals? I am suggesting that clock offset is primary to clock jitter. > Oddly enough, my ~25 year experience with ntpd suggests a great deal of > practical > experience has gone into creating a timekeeping solution that avoids > chasing short-term > transients in favor of stable long-term behavior. > > However, it's certainly OK if someone decides that some other software > provides a better > solution for their particular circumstances.... > > > My computer has a -19 precision but it can't keep time inside 1 > millisecond with default > > Settings; go figure. > [Mischanko, Edward T] I have common PC running Windows XP with 10 peers on my side of a corporate firewall. > Precision of -19 suggests commonly available commodity hardware. Keeping > time to around 1ms > should be reasonably doable with a decent network connection, at least 4 > reasonable peers > or time sources to query, temperature-controlled systems, and an OS with > sane timekeeping; > VMs need not apply regardless of OS. > > It might help to setup a subnet local peering of ~4 or so machines, in > addition to the > remote time sources or a GPS/ACTS/WWVB or similar stratum-1 source. > > Regards, > -- > -Chuck _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
