Slow clock in openSUSE 10.3 guest

egandb · Post by **egandb** » 13. Aug 2008, 14:16

Make sure to install VBox Guest Additions in your virtual machines. I spent a lot of extra time, re-installed, re-configured, etc… only to find out that I needed to use the nohz=off kernel option and Guest Additions to get my guest system clock to run at normal speed. Without Guest Additions installed, the clock on my openSUSE 10.3 guest ran extremely slow, unless I had my Win2k guest off.

Setup:
Host: openSUSE 10.3
Guest 1: Win2K
Guest 2: openSUSE 10.3

"Werx gud ya!"

Post by **frank** » 7. Sep 2008, 22:29

Are you sure that you compiled the vboxdrv module against the correct kernel sources? I've read some reports like this and every time the problem was that the CONFIG_HZ option of the running kernel was different from the kernel sources vboxdrv was compiled against.

egandb · Post by **egandb** » 8. Sep 2008, 05:26

Not sure exactly what you're talking about, but I followed the installation instructions as they were provided and it's been working alright since I installed the Guest Additions.

Post by **frank** » 8. Sep 2008, 12:25

I'm talking about the problem that your time was apparently not properly synchronized between guest and host. This can happen for small time differences but not for big differences. I've seen some people reporting problems that their guest clock seems to run at a notably slower or faster speed than the host clock. In almost every case the reason was a miscompiled vboxdrv host Linux kernel module.

egandb · Post by **egandb** » 8. Sep 2008, 15:53

AFAIK, I compiled it correctly for the kernel version I'm running on. Again, followed directions, but until I installed the Guest Additions, the clock ran very, very slow. I want to say roughly 1 second guest = 4-5 seconds host. Scary slow!

Post by **Sasquatch** » 8. Sep 2008, 20:55

If you run it on a laptop, it's possible that the CPU runs at full speed during boot and then trottles back due to powernowd or any other daemon that can change the CPU speed. The other way around is also possible for a clock that is too fast.

Post by **frank** » 9. Sep 2008, 16:51

egandb, I still assume that the kernel module was wrong compiled, sorry. I've seen to many such reports. The best way to find that out is to completely recompile your kernel, install it and to recompile the kernel module and use it. Of course if this will have a low priority for you if you are happy with the current solution.

Clocking down the CPU frequency shouldn't be an issue with VBox 1.6 anymore.

Post by **Sasquatch** » 9. Sep 2008, 19:52

Frank Mehnert wrote:Clocking down the CPU frequency shouldn't be an issue with VBox 1.6 anymore.

I didn't know if VB had this issue or not, but VMWare did/does. Thought it might be related.