Feb 212010
Paravirtualized Clocks
In theory, Xen dom0′s are supposed to forcibly sync their system clock to the domU’s. In practice, due to some incompatibility between either Ubuntu’s version of the dom0 or domU patches, that doesn’t work, even though the feature is enabled, which leads to clock drift and occasionally weird clock lockup bugs.
The easiest way to fix this is to disable the Xen clock syncing entirely, and rely on the standard Linux clock mechanism. You can do that by adding these two lines just before exit 0 in /etc/rc.local:
echo '1' > /proc/sys/xen/independent_wallclock echo 'jiffies' > /sys/devices/system/clocksource/clocksource0/current_clocksource
You’ll want to be sure to run NTP or some other service to keep your clock in sync.