idle grub guest, host cpu at 100%

[jefft]

I've installed Centos 5.3 and Fedora 11 as virtual machines. On my Mac both cause the host CPU to run at 100% (viewed by top), even when the guest is idle. While trying to figure out why, I've noticed that this happens even before the OS is loaded (i.e. just the grub boot loader itself causes the host CPU process to run at 100%).

To confirm that it was not a problem of the grub included in Centos and Fedora, I download a "grub-only" CD image.

The image (Super Grub) is described here:
http://en.kioskea.net/faq/sujet-2677-su ... sk-live-cd
List of all CDs (different versions):
http://download.linux-live-cd.org/Super ... sgd/cdrom/
The CD I downloaded (latest version) was:
http://download.linux-live-cd.org/Super ... 0.9795.iso

The problem still occurred. That is, booting this CD in a virtual machine causes the host CPU process to be at 100%, even though grub is doing nothing except waiting for keyboard input.

Why should an idle boot loader cause the host CPU to run at 100%?
I think solving this problem will likely also solve the 100% CPU problem with Centos and Fedora.

For the above, I was using the latest VirtualBox (3.0.0) on the latest Mac OS X (10.5.7).

[Perryg]

This might help, http://forums.virtualbox.org/viewtopic.php?f=7&t=17926

[Sasquatch]

This is normal behaviour. You would get the same thing on your Host directly, you just don't see it. The reason for this, is that idle cpu is set through ACPI, and that isn't loaded in Grub, it's not meant for it. Other Guests, like DOS and Windows 9x have the same problem, 100% CPU usage when running. For Win 9x, this can be solved, but DOS and the sorts will still show this 'abuse'. Nothing VB can do about.