On Thu, Feb 19, 2015 at 10:05:45AM +0000, Rob wrote: > We have systems in places that are not temperature controlled and then > chrony is much better. I am looking for the best way to find the > values to use in the tempcomp configuration directive.
What resolution does the sensor have? Don't expect good results with 1C or 0.5C resolution that sensors on mainboards typically have. > Ideally there would be a program that analyzes a log of momentary > temperature and frequency values to find the coefficients, but how > is such a logfile even generated? > > Should I enter a tempcomp line with zero coefficients and then use > the tempcomp logging? Yes, you can use that or you can collect data from the sensor file with a "while true; do echo $(date +'%s'; cat /sys/...); sleep 1; done" script independently from chronyd. After collecting enough data over a wide range of temperature you need to pair the temperature values with frequency from the tracking log and find the coefficients for the quadratic function, or (with 2.0-pre1) it's easier to create a file containing list of (temperature, correction) points for the second form of the tempcomp configuration. For example, you could divide temperature in 0.1C intervals and use mean frequency offset as the correction. Not sure if it needs to be negated or not, I always forget. I agree it would be nice to have a script that would automate this process. -- Miroslav Lichvar _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
