thorinn@DIKU.DK (Lars Henrik Mathiesen) (12/03/90)
Archive-name: internet/ntp/ntp-timed-patch/1990-12-02 Archive: freja.diku.dk:misc/ntp-timed.patch [129.142.96.1] Original-posting-by: thorinn@DIKU.DK (Lars Henrik Mathiesen) Original-subject: NTP and the infamous SPARC clock problem (again) Reposted-by: emv@ox.com (Edward Vielmetti) Edward, We run a flock of VAXen on ntp, and on those we run a jimmied timed whose only function is to act as master for our various Suns (*). This works fine now that we've set dosynctodr to 0 in the Sun kernels; I just checked, and most Suns are within 25 ms of the current timed master. The SparcStations all run very fast and will gain about 75 ms between timed syncs (every four minutes); but as someone suggested, we could set tick to 9998 which would probably bring them into line. (Before we reset dosynctodr, we'd see the SparcStation clocks slew up to sync once every four minutes and then slew even faster (about 1 second in two!) back to an (increasing) offset of up to 20 seconds. When the offset grew larger than that, timed would log a complaint and do a settimeofday, starting the cycle again.) It seems that an unloaded SparcStation with dosynctodr==0 is about 300 ppm fast (about 30 seconds a day). When it was set, they'd generate a timed log message every three to four hours during working hours only (about 1500 ppm slow). I guess the slowness when loaded is due to lost clock interrupts although I'm unable to imagine what sort of bogosity in SunOS is is that makes this time loss persistent when using the time-of-day register. Lars _____________________________________________________________________ (*) Patches for anonymous ftp at freja.diku.dk:misc/ntp-timed.patch .