[CentOS-virt] Fast clock under VMWare

[Ray Van Dolson]

On Fri, Feb 22, 2008 at 12:12:59PM -0500, chanms wrote:
> Hi everyone,
> 
> I have been struggling with having the clock of Linux VM's (including
> CentOS 4.6 and 5.1) running very fast under VMWare, no matter what I
> have tried.
> 
> My platform:
> - AMD Turion X2 TL-60
> - AMD 690 chipset with integrated Radeon x1250 (probably doesn't
> concern in this case)
> - Windows Vista Ultimate x64, all Windows Update patches loaded (no SP1 yet)
> - 4GB RAM
> - VMWare Workstation 6.0.2
> - BIOS has no options to disable power management, etc.
> 
> On my host PC
> - C:\ProgramData\VMware\VMware Workstation\Config.ini, put in
> host.cpukHz = "2000000", host.noTSC = "TRUE", ptsc.noTSC = "TRUE"
> - AMD's dual core optimizer loaded
> 
> On CentOS 5.1 VM
> - use kernel options "noapic nolapic nosmp clocksource=acpi_pm"
> - use "divider=10" option in the regular kernel
> - try the vm version of the kernel in centos-plus with the same kernel
> options in first line
> 
> No matter what I try, the CentOS clocks are still fast - at a rate of
> almost 2 seconds for every 1 real second.
> 
> What other things I can do in order to fix this?

I think the typical fix for the clock-too-fast problem is to boot your
guest OS with the clock=pit option and then use the VMware Tools time
synchronization option.

If the clock is running too slow is where you want to look into using
one of the 100Hz kernels.

See:
  http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&externalId=1420

Ray