-------- In message <60CC0E0EEEE34928B664249EAC88407F@pc52>, "Tom Van Baak" writes: >> http://phk.freebsd.dk/time/20141018.html > >PHK, > >This is the best news I've heard in a long time; an overhaul of NTP!
Indeed :-) >Instead of tweaking GPSDO algorithms or tuning parameters and >having to wait days to see if it works or not, the idea was to >"replay" pre-recorded 1PPS data and pre-recorded oscillator data >into the PLL. This means one can test any new design change in a >GPSDO in a matter of seconds instead of days. > >So the question is -- could you do the same for NTP? Well, first of all it's not days any longer. My proto-PLL wrangles the clock phase in a matter of seconds and frequency in a few minutes. Some of the (really) old NTP assumptions and metrics no longer hold, revisiting them opens up a lot of parameter space. Second, I'm already doing such simulations, and the ability to do that is part of the design basis of what I'm doing. I spent a month of my NTP-time trying to resurrect the "SIM" code in ntpd, in order to get some kind of reproducible test-bench going and in the end I concluded that 100k lines of code is not the way forward. My current plan is to release a brand new client-only NTP daemon with a decent PLL and high attack resistance before X-mas and then work from there to one or two other programs: NTP-slave server (ie: stratum 2..14) and a NTP-master/stratum 1 server. All along the way, the intent is to try to pull PTP into this also, since there is no material (ie: only protocol) difference between a NTP and PTP timekeeping program, and the user shouldn't need to notice the difference. More as it happens. The "mini-blog" entries I've started will happen every so often when there is some progress to report or interesting data to present. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.