May 27 2011

VMware: Host Power Management Causes slowdown on virtual machines

Category: vmwareAbhishek Shukla @ 12:13 | |

Common problems for slow virtual machines are CPU throttling caused by the Power Management on host machine, and IO problems.

This will discuss how to avoid the CPU throttling done by Intel SpeedStep and AMD Cool ‘n’ Quiet.


1: Find out what your CPU speed is.

If you don’t know rightclick on “My Computer” and click “Properties”.

About 2/3 down it says:

Dell Latitude D630

Intel(R) Core(TM) Duo CPU

T7500 @ 2.20GHz

The 2.2GHz is what we’re looking for.


2: Open VMware global configuration fine (config.ini)

Location is:

Windows XP / Windows Server 2000 / 2003:

%AllUsersProfile%\Application Data\VMware\VMware Workstation\config.ini

Windows Vista / Windows 7 / Windows Server 2008:

C:\ProgramData\VMware\VMware Workstation\config.ini

“VMware Workstation” needs to be replaced if that is not the product used.


3: Edit config.ini

3 lines needs to be copied to the config.ini file:

host.cpukHz = “2200000″
host.noTSC = “TRUE”
ptsc.noTSC = “TRUE”

The cpu speed is listed in kiloherz, and your CPU is most likely listed in gigaherz where we looked it up.

Multiply the gigaherz with 1.000.000 (1 million) and you have your speed in kiloherz.

The value above is for 2.2 GHz. If you have 2.4 GHz for instance, just replace the “22″ with “24″.


4: Make sure time synchonisation is enabled on client.
Double click the VMware tools icon in “Notification Tray” and select the “Options” tab. Make sure “Time synchronization between the virtual machine and the host operating system”


5: Restart VMware Authorization service
Click Start -> Control Panel -> Administrative Tools -> Services
Rightclick VMware Authorization and choose Restart

Start up your Virtual Machine now and you should experience better CPU speeds.