| Re: [chrony-users] RTC trim and offset reduced to 1ms |
[ Thread Index |
Date Index
| More chrony.tuxfamily.org/chrony-users Archives
]
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 |____ unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/
On Thu, 16 Jan 2020, Seoli Luca (M) wrote:
Hi all,
I’m trying to configure chronyd to set RTC time considering System time and its variations. In
particular, I’d like to get an offset between RTC time and Sys time less than 1ms
(milliseconds). Is it possibile?
Why? The rtc is there to set the system clock after shutdown. The rtc and
system crystals have different physical parameters and drift at different
rates. So if you got them synchronized (1ms) now, a few minute later they would not be.
Setting the rtc is difficult. At least with some of the rtc, you can only set
them to the 1 second mark, and you must do so something like 1/2 a second
early.
This sounds to me like a vanity exercise ("lets see if I can do it") rather
than a needs exercise.
Below my configuration file and some statistics I found in my rtc.log file.
---- Configuration File ----
hwclockfile /etc/adjtime
rtcautotrim 0.001
rtcdevice /dev/rtc
rtcfile /var/lib/chrony/rtc
logdir /var/log/chrony
log rtc statistics measurements tracking
dumponexit
---- Statistics -----
Date (UTC) Time RTC fast (s) Val Est fast (s) Slope (ppm) Ns Nr Meas
===============================================================================
2020-01-16 09:59:14 0.019363 0 0.000000 0.000 1 0 15
2020-01-16 09:59:15 0.019269 0 0.000000 0.000 2 0 15
2020-01-16 09:59:16 0.019006 0 0.000000 0.000 3 0 15
2020-01-16 09:59:17 0.018822 0 0.000000 0.000 4 0 15
2020-01-16 09:59:18 0.018606 0 0.000000 0.000 5 0 30
2020-01-16 09:59:19 0.018448 0 0.000000 0.000 6 0 30
2020-01-16 09:59:20 0.018225 0 0.000000 0.000 7 0 60
2020-01-16 09:59:21 0.018010 0 0.006622 -195.346 -1 7 60
2020-01-16 09:59:37 0.001297 0 0.006622 -195.346 0 7 15
2020-01-16 09:59:54 0.000403 0 0.006622 -195.346 1 7 15
2020-01-16 10:00:11 0.010295 1 0.010295 -89.252 2 0 15
2020-01-16 10:00:28 0.009355 1 0.009355 -75.462 3 0 15
2020-01-16 10:00:45 0.019718 1 0.016737 129.695 4 3 15
2020-01-16 10:01:17 0.018735 1 0.018735 111.847 5 4 30
2020-01-16 10:01:49 0.017672 1 0.017672 49.485 6 2 30
2020-01-16 10:02:51 0.016538 1 0.020698 49.241 7 3 60
2020-01-16 10:03:53 0.015583 1 0.018134 25.735 8 3 60
2020-01-16 10:04:55 0.014584 1 0.019387 24.595 9 4 60
2020-01-16 10:05:57 0.013650 1 0.013650 -15.534 10 6 60
2020-01-16 10:07:59 0.012603 1 0.012232 -13.628 11 4 120
Thank you very much!
Luca
Luca Seoli
Software Integrator Engineer
Electronics – Technology Innovation
Phone: +390118269316
Marelli
V.le Carlo Emanuele II 118/150, Venaria Reale (Torino), Italy
www.marelli.com
cid:image001.jpg@01D577BF.28F4D310
Please note our web domain and email
account have changed to marelli.com
CLASSIFICATION
I
P – Public / I – Internal / C – Confidential / S – Secret
Confidential : Do not forward without agreement
VISIT OUR WEBSITE! - VISIT OUR WEB SITE! www.marelli.com Confidential Notice: This message -
including its attachments - may contain proprietary, confidential and/or legally protected
information and is intended solely for the use of the designated addressee(s) above. If you
are not the intended recipient be aware that any downloading, copying, disclosure,
distribution or use of the contents of the above information is strictly prohibited. If you
have received this communication by mistake, please forward the message back to the sender at
the email address above, delete the message from all mailboxes and any other electronic
storage medium and destroy all copies. Disclaimer Notice: Internet communications cannot be
guaranteed to be safe or error-free. Therefore we do not assure that this message is complete
or accurate and we do not accept liability for any errors or omissions in the contents of this
message