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System clock runs fast in a Linux guest Virtual Machine


A Linux guest virtual machine continually gains time.

The hardware clock is showing the correct time:

hwclock --show

VMware Tools are installed in the guest OS, and the following option is present in the .vmx file:

tools.syncTime = "TRUE"

Adding the following kernel command line option does not resolve the issue:



Use the ACPI Power Management Timer with the following kernel command line option:


Note: From kernel 2.6.16 the clock= command line option is deprecated and the following option should be used:


The following option may be better suited to a Linux guest with kernel 2.6.21 or later and to VMware products such as VMware Workstation 6 that provide "VMware paravirtual kernel support":


The following document lists a per distribution/version of VMware recommended kernel parameters:

Timekeeping best practices for Linux guests


Check the current kernel command line clock parameter with the command:

dmesg | grep clock

If the tools.syncTime = "TRUE" is not set, shut down the virtual machine, add the tools.syncTime = "TRUE" line to the .vmx file, either by editing the file or by using Edit Settings | Options tab | Advanced setting | Configuration Parameters button in VirtualCenter Client, and restart the virtual machine.

Time: Clocksource Infrastructure
clock={ pit | tsc | cyclone | pmtmr }
clocksource={ jiffies | acpi_pm | pit | hpet | tsc | vmi-timer }

Timekeeping in VMware Virtual Machines


VMware ESX 3

Created: 7th August 2007
Updated: 22nd July 2010

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