Windows 7/8/2008/2012 causing high CPU loads on KVM

Windows 7/8/2008/2012 causing high CPU loads on KVM

If Windows 7/8/2008/2012 causing high CPU loads on KVM it could be a Clock Timing Error which causing this.

To use the KVM Platform Clock you can enable it within your Windows by using BCDEdit in your Admin CMD Shell:

bcdedit /set {default} useplatformclock true

Also be sure to disable automatic Time Syncing with Microsoft Server.

For Windows XP or Windows 2003 Server Systems:
To enable the Platform clock on next reboot for Windows XP or 2003 you have to enable the usepmtimer switch in your boot.ini

You have to open the C:boot.ini file with notepad (cmdline: notepad C:boot.ini) and append the value /usepmtimer so the line finally looks like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /usepmtimer

On KVM append localtime to KVM command like:

kvm -localtime

If you are using Libvirt/Virsh enable Your Clock offset to localtime like this:

clock offset='localtime'

Have fun!

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Description about the Tool BCDEdit used in this article:
Boot Configuration Data (BCD) files is a very useful tool by Microsoft to add and modify boot applications and boot application settings.
The objects that gets stored in it’s own elements database stores objects is a full replacement for the OS related and previous used Boot.ini configuration file.

BCDEdit is a command-line script for managing those BCD entries. You can use it for different purposes, including creating new datastores, modifying existing stores, adding boot new menu options, and more. BCDEdit supports almost the same purpose as Bootcfg.exe on earlier versions of Windows, but with major improvements like a wider range of boot options than Bootcfg.exe and BCDEdit has advanced scripting support.

BCDEdit delivers support for editing the boot configuration of Windows Vista and later versions of Microsoft Windows products.
It is included since the Windows Vista distribution in the %WINDIR%System32 folder.

About KVM -localtime used in this article:
Description quoted from the Official Manpage: Set the real time clock to local time (the default is to UTC time). This option is needed to have correct date in MS-DOS or Windows.
KVM stands for Kernel-based Virtual Machine a full virtualization solution for Linux.