Changes between Version 3 and Version 4 of ntp

Timestamp:

01/24/2017 11:23:55 PM (7 years ago)

Author:

ken@…

Comment:

This is a workaround for dodgy kernels. See #8759

ntp

@@ -45 +45 @@
 }}}
 
+== Fixes if synchronisation fails ==
+
+For a long time the default kernel clocksource has been tsc, but it used to be acpi_pm. On one of my machines, in one kernel release, I lost synchronisation and the log showed:
+{{{
+frequency error 1726 PPM exceeds tolerance 500 PPM
+}}}
+
+Google found a not-too-old link to redhat [​https://access.redhat.com/solutions/35640] which suggested checking the available drivers with
+{{{
+cat /sys/devices/system/clocksource/clocksource0/available_clocksource 
+}}}
+and assuming that acpi_pm is available, temporarily changing to it with
+{{{
+echo acpi_pm >/sys/devices/system/clocksource/clocksource0/current_clocksource 
+}}}
+and seeing if that helps. If useful, it can forced by adding
+{{{
+clocksource=acpi_pm
+}}}
+to the bootargs in grub.
+
+== When the clock is too far away from the correct time ==
+
+If ntpd bails out because the clock is too far from the correct time, try stopping ntpd, using
+{{{
+ntpd -gq
+}}}
+to let it sync, and then restarting ntpd. According to the man page, -g can be used multiple times if the clock is far adrift.
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