[CentOS-virt] Fast clock under VMWare

chanms chanms at gmail.com
Fri Feb 22 17:12:59 UTC 2008

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)
- 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?

M. Chan

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