The following is a snippet from the Release Notes for CentOS 5.1

I need to change the system clock rate for my Trixbox VM but I dont understand what sysfs is, or exactly where and to what file I need to add this paramater. Can someone please point me in the right direction?

tick_divider

The tick_divider= option is a sysfs parameter that allows you to adjust the system clock rate while maintaining the same visible HZ timing value to user space applications.

Using the tick_divider= option allows you to reduce CPU overhead and increase efficiency at the cost of lowering the accuracy of timing operations and profiling.

Useful for the standard 1000Hz clock are:

  • 2 = 500Hz

  • 4 = 250Hz

  • 5 = 200Hz

  • 8 = 125Hz

  • 10 = 100Hz (value used by previous releases of Red Hat Enterprise Linux)

Note that the virtualized kernel does not support multiple timer rates on guests. dom0 uses a fixed timing rate set across all guests; this reduces the load that multiple tick rates could cause.