With the latest improvements in the chrony package related to NetworkManager and name resolving I think it is now good enough to replace ntpd in the default configuration and the configurations supported by system-config-date. I'm proposing to add a support for chrony to system-config-date and change the dependency. As chrony supports only a subset of the NTP protocol and misses many of the ntpd features, users will have to install the ntp package manually if they have a specific requirement or need to use a more complicated configuration. The reasons why I think chrony might be a better choice for default installation: Ntpd seems to be primarily designed for server environments, it doesn't work very well when restarted frequently, because it needs a lot of time to settle down. This is further worsened when tsc is used as the system clocksource. Due to unstable kernel calibration the clock drift may change between reboots by hundreds of ppm and ntpd will need about 10 hours to settle down, while chrony needs only 10 minutes. Even when everything has settled down, chrony is usually able to control the clock 2-3 times better than ntpd. In some situations the difference is even greater. Chrony doesn't step the system clock unless configured to do so. Our default config allows stepping in first three clock updates and only if the error is larger than 30 seconds. OTOH, ntpd will step the clock whenever the assumed error is larger than 128 ms. It can be configured to not do that, but this will disable kernel discipline which may negatively affect the timekeeping performance and power saving as the daemon will have to wake up every second. Chrony has a smaller memory footprint. I'd say the only major drawback is that chrony is not as widely tested as ntpd and there could be serious bugs hidden. Although the project is now over 12 years old, the user base seems to be very small. What do you think? -- Miroslav Lichvar -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
