[arch-general] system time stucks in a loop

Thomas Bächler thomas at archlinux.org
Fri Oct 22 10:29:24 EDT 2010

Am 22.10.2010 16:20, schrieb János Illés:
> I learned that the clock kernel parameter is deprecated, it is now
> called clocksource. Still it is somehow gets ignored, and the kernel
> uses acpi_pm instead.
>   $ dmesg|grep clock
>   Kernel command line: root=/dev/sda1 resume=/dev/sda2 rootdelay=1 ro
> vga=787 clocksource=pit
>   Measured 18368 cycles TSC warp between CPUs, turning off TSC clock.
>   Switching to clocksource acpi_pm

Look at this:

$ cd /sys/devices/system/clocksource
$ ls -F
$ cd clocksource0/
$ ls -F
available_clocksource  current_clocksource
$ cat available_clocksource
tsc hpet acpi_pm
$ cat current_clocksource

Playing around here might help or give ideas. As far as I know, 'tsc' is
a bad choice for a clocksource (not sure why or if I am even correct),
but a good fallback when acpi_pm fails and hpet is unavailable.

Under KVM, I have a special KVM clocksource which synchronizes with the
host clock. Similarly on Xen.

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