William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273 Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324 UBC, Vancouver,BC _|_ Program in Cosmology |____ un...@physics.ubc.ca Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/ On Mon, 20 Nov 2017, Gernot Nusshall wrote:
Hi, i am not sure if i am experiencing a problem with chrony or the linux kernel. I want the rtc to be updated with the 11-minute-mode of the linux kernel initiated with the chrony option „rtcsync“.
Why would you want to do that? That is a much worse way of disciplining the rtc than almost anything else. It goes back to the early days of computers before ntp where the system clock would be updated by getting time from somewhere and just resetting the system clock to that time. chrony disciplines the rtc just as it disciplines the system clock. It measures the drift rate of the rtc and the offset of the rtc. Then when it is started it reads the old offset, the old drift rate, and corrects the rtc by those amounts. Now this is not idea, since the drift rate of the rtc when the computer is cold is probably different than what it is when it is operating and warm, but it is lot better than just jumping the rtc every 11 min. Ie, you are trying to work against chrony which is incomprehensible.
I was expecting that the rtc is getting updated because the adjtimex output set by chrony seems correct and the kernel config options are also set correctly, is there anything that i am missing?
Yes. and understanding of how chrony works.
thanks in advance, Gernot # set hwclock to something not equal local time/utc root:~# hwclock --set --date 00:03:09 root:~# reboot root:~# systemctl stop chronyd
Agagagagarhehgh. Please understand how chrony works. By putting in that jump into the rtc, all chrony's efforts to understand the rate and offset of your rtc have been negated. Ie, this is a silly test because it would not happen in reality.
# check if rtcsync is enabled root:~# cat /etc/chrony/chrony.conf logdir /var/log/chrony logbanner 32 logchange 0.5 noclientlog log measurements log statistics log tracking makestep 1.0 -1 acquisitionport 123 manual rtcsync server 192.168.253.1 maxpoll 10 # start strace (start chronyd) nohup strace -f -tt -o time.strace /usr/sbin/chronyd -u _chrony & https://pastebin.com/g9aNHkzV # check 11-minute-kernel-mode:
Chrony purposely disables kernel 11 min mode because it completely negates the whole effort chrony puts in to understanding the rtc.
