Wednesday, October 3, 2007

Ubuntu Host with Windows Guest Time Sync Problem

I've been running VMware server for 3-4 months on an Intel Duo Core 2 with Ubuntu Fiesty Fawn as my host OS. My windows guests would always run too fast and every article I could find about time sync issues only showed how to change the boot clock variable to clock=pit or clock=pmtmr under grub or lilo.

The problem and fix are different from what this vmware knowledgebase article. Clock in a Linux Guest Runs More Slowly or Quickly Than Real Time

This is the correct knowledgebase article from vmware. Host Power Management Causes Problems with Guest Timekeeping (Windows Hosts)


Quick Solution Steps

Install cpufrequtils and run cpufreq-info to get maximum frequency

Autoedification: VMware guest clock runs fast
Since my max CPU is 1.83 GHz, I added these lines to

host.cpukHz = 1830000
host.noTSC = TRUE
ptsc.noTSC = TRUE


Unfortunately, you will have to modify this file every time you run vmware-config to recompile the vmware modules for a new kernel.  I'm going to keep a copy under /etc/vmware/config.bak and run a quick 'sudo cp /etc/vmware/config{.bak,}'  after every time I need to recompile.


  1. Thanks for this post! I've been having issues with this for some time now - this worked perfect on Gutsy!

  2. Why can't one use the syncing option from the guest vmware tools? There is an option to sync the guest clock to the host clock..??