Clock Sources Explanation For x86_64 -- acpi_pm, jiffies, tsc -- Virtualization Imapct -- VMWare, Xen

[Robert L Cochran <cochranb@xxxxxxxxxxxxx>]

Here are the clock sources my Fedora 7 x86_64 kernel considers to be 
available:

[root@bobcp4 ~]# cat 
/sys/devices/system/clocksource/clocksource0/available_clocksource
acpi_pm jiffies tsc

Where can I find an explanation of these -- is there a writeup that can 
help me decide which one is best to use?

My system is using acpi_pm. How would this impact VMWare or Xen guests?

Thanks

Bob Cochran