Thank You Ed!
On 10/22/2017 1:47 PM, King Beowulf wrote: > On 10/22/2017 12:49 PM, Dave Lien - W7DAL wrote: >> /... //the install process usually sets it up for you./ >> >> Thanks Jim and Larry! >> >> I've been watching the flow of contacts using FT8 over the past several >> days without doing anything about time correction. With continuously >> positive results over many hours of system ON time I now have no reason >> to believe drift is a factor to be addressed. >> >> Also, I've never seen a reference to having to add special time adjust >> software when Linux is used with this time critical digital >> communications mode. Such a software addition is pretty much mandatory >> with Windows and is well publicized by FT8 and other digital mode users. >> >> So, I've decided to just leave things alone. . TNX. > > Just as an FYI (and late to the party as usual), I have this is my start > up /etc/rc.d/rc.local, along with the appropriate settings in : > > # Set the time > /usr/sbin/ntpd -qg > /sbin/hwclock -w > > This syncs up both hardware and system clocks at the end of the boot cycle. > > The motherboard hardware clock can and does drift a bit over long time > scales. These clock chips have always been awful. It does not matter > the OS you are running. The system (software) clock is even worse, > although does not seem to be as bad as in Windows. > > http://www.tldp.org/HOWTO/Clock-2.html > > Running ntp continuously is a bit overkill for my needs. Here is my > time drift on recent reboots for kernel and nvidia driver updates: > > # last reboot > reboot system boot 4.4.88 Fri Oct 13 00:58 - 13:10 (9+12:11) > reboot system boot 4.4.88 Thu Oct 12 15:07 - 00:57 (09:50) > reboot system boot 4.4.75 Mon Sep 4 13:32 - 15:05 (38+01:32) > > # cat messages.2 |grep ntpd > Oct 12 15:07:20 gandalf ntpd[1431]: ntpd [email protected] Thu Apr 20 > 17:49:20 UTC 2017 (1): Starting > Oct 12 15:07:20 gandalf ntpd[1431]: Command line: /usr/sbin/ntpd -qg > Oct 12 15:07:20 gandalf ntpd[1431]: proto: precision = 0.114 usec (-23) > ... > Oct 12 15:07:29 gandalf ntpd[1431]: ntpd: time set +2.169528 s > Oct 13 00:59:03 gandalf ntpd[1432]: ntpd [email protected] Thu Apr 20 > 17:49:20 UTC 2017 (1): Starting > Oct 13 00:59:03 gandalf ntpd[1432]: Command line: /usr/sbin/ntpd -qg > Oct 13 00:59:03 gandalf ntpd[1432]: proto: precision = 0.111 usec (-23) > ... > Oct 13 00:59:12 gandalf ntpd[1432]: ntpd: time slew +0.032806 s > > Thus, after an uptime of 38 days, the time drift was +2.169528 s and > then after 9 days, +0.032806 s. For comparison, after 20 days up, my > antique ~10 yrs old HP Pentium 4 box (Intel motherboard) drifted > +81.659436 s > > It all depends on your application and needs as to how accurate you > computer time needs to be. For time critical software, depending on the > actual motherboard drift, you can calculate any required ntp update > interval. > > -Ed > > _______________________________________________ > PLUG mailing list > [email protected] > http://lists.pdxlinux.org/mailman/listinfo/plug _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
