virtualbox.org

rpmurray wrote:What happens if you use VBoxManage to adjust the TSCTicksPerSecond?

VBoxManage setextradata "VM Name" "VBoxInternal/TM/TSCTicksPerSecond" 2530000000

As was mentioned earlier, this indeed improves the situation. However, it does not completely solve it because of how OS X apparently adjusts its value of the TSC rate to be a integer multiple of the bus frequency. OS X end up setting the TSC and CPU rate to 2400000000. When I try setting "VBoxInternal/TM/TSCTicksPerSecond" to higher values it does not change what OS X assigns to "machdep.tsc.frequency" until eventially for high enough values of "VBoxInternal/TM/TSCTicksPerSecond" it jumps to 2800000000, and so on.
That is why I was looking for an option to set the bus frequency declared by EFI that the guest OS X picks up, to force it to the same value as seen by OS X on the host.

michaln wrote:Try running OS X guest on a newer Mac that has a post-Core 2 CPU and then tell me why it behaves differently

Unfortunately the VM wasnt able to boot on a newer machine. CPU usage of VirtualBox went to 100% and just hung there. Will have to see how much time I can spend on trying to debug that one.

Artur wrote:As was mentioned earlier ...

No, you didn't mention that earlier. You said you used the "VBoxInternal/TM/MaybeUseOffsettedHostTSC" configuration option.

rpmurray wrote:

Artur wrote:As was mentioned earlier ...

No, you didn't mention that earlier. You said you used the "VBoxInternal/TM/MaybeUseOffsettedHostTSC" configuration option.

Sorry, you are right. I should have written TSCTicksPerSecond. I fixed the original post.
Thanks for pointing out the typo.
But to answer your question, setting TSCTicksPerSecond improves the situation but due to this apparent quantisation the kernal code applies it cannot solve the problem completely.

Artur wrote:I fixed the original post.

Just a general advice. Usually you don't go back and edit your original post, or if you do, you make sure that you point out what the revisions were, otherwise the discussion following your original post are going to look irrelevant.