VirtualBox

Ticket #4837 (closed defect: fixed)

Opened 5 years ago

Last modified 3 years ago

Linux guest clock skew problems go away with nohz=off

Reported by: robinsmidsrod Owned by:
Priority: minor Component: documentation
Version: VirtualBox 3.0.4 Keywords: nohz, nohz=off, tickless, timer
Cc: Guest type: Linux
Host type: Windows

Description

The user faq states that setting nohz=off should not be necessary after virtualbox 1.6.

I'm running VirtualBox 3.0.4 on a Vista x64 host with a Ubuntu 8.04 server 32bit guest, and I had make clock skew problems consistently.

Setting nohz=off made it go away.

Change History

comment:1 Changed 5 years ago by frank

  • Summary changed from User FAQ wiki entry stale with regards to nohz=off option to Linux guest clock skew problems go away with nohz=off

Well, the wiki entry is related to Linux hosts while your problem is related to a Linux guest.

comment:2 Changed 5 years ago by robinsmidsrod

Oups, guess I overlooked that.

I guess it could be mentioned in the section about Linux guests then.

comment:3 in reply to: ↑ description Changed 5 years ago by joe42

Replying to robinsmidsrod:

The user faq states that setting nohz=off should not be necessary after virtualbox 1.6.

I'm running VirtualBox 3.0.4 on a Vista x64 host with a Ubuntu 8.04 server 32bit guest, and I had make clock skew problems consistently.

Setting nohz=off made it go away.

I have a SLES 10 SP2 amd64 guest under a Solaris 10 host where the guest clock ran about 1.5-2x the speed of the host clock.

  • This happened with and without guest additions
  • This happened on VB 3.0.4 and 3.0.6
  • This happened with and without nohz=off

The solution to the problem was to run the guest with a non-SMP kernel so that I could disable the IO-APIC. Without IO-APIC the guest clock is accurate - with it, it drifts wildly.

comment:4 Changed 3 years ago by frank

  • Status changed from new to closed
  • Resolution set to fixed

Please reopen if still relevant with VBox 4.0.4.

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