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Technogeezer
Immortal
Immortal

Preferred virtualization engine preference

I'm a bit curious about the new advanced preference in Fusion 3.0 to select the preferred virtualization engine. How does Fusion make the determination of the engine to use if the setting is kept to its default of "Automatic"?

I've also found some interesting behavior - I have a 2.0 GHz Core 2 Duo iMac (iMac 5.1). If I leave the virtualization engine as "Automatic" on my 32-bit XP VM things work fine. If I change it to Intel VT-X, the VM constantly consumes nearly 100% CPU (as noted by both the vmware-vmx process on the Mac side and Task Manager inside the VM). If set to "Binary Translation", I get a warning message about long mode support, and the VM consumes more reasonable CPU (it actually goes to near 0% when XP is idle). This CPU behavior is exactly like "Automatic", so I assume that Binary Translation is being automatically selected for Automatic in this case.

- Paul (Technogeezer)
Editor of the Unofficial Fusion Companion Guides
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admin
Immortal
Immortal

That's interesting, and sounds like a bug. When set to VT-x, what process does Task Manager in the guest show as taking up CPU?

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nbe
Enthusiast
Enthusiast

There are 2 VT-x options, did you choose "Intel VT-x" or "Intel VT-x with EPT" ?

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admin
Immortal
Immortal

See . Though this document refers to ESX, the same criteria apply to Fusion 3.

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Technogeezer
Immortal
Immortal

I've set the engine to Intel VT-X. If I set to Intel VT-X with EPT, it notes that my hardware does not support this.

I've been doing a bit more digging into this.

vmware-vmx is the Mac process that hangs at around 100% CPU usage for an extended period.

Within the VM, the task manager is reporting that the CPU is pegged, with almost all of that in kernel time.

After about 15 minutes, I'm finally seeing system idle time.

I'm seeing background processes run, but they appear to be taking more CPU resource and running longer than with Binary Translation. All of this behavior eventually tends to settle out after time (where I get to see some System Idle Process time) but the vmware-vmx process never settles out to using under 10% CPU time at an "idle" state like it did with Binary Translation.

If I switch back to "Automatic" or "Binary Translation" this behavior all goes away... Is it that VT-x just doesn't work as well on my system?

- Paul (Technogeezer)
Editor of the Unofficial Fusion Companion Guides
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admin
Immortal
Immortal

VT-x is generally a poor choice for 32-bit Windows XP guests on systems without FlexPriority, because Windows XP really likes to pound on the TPR, which causes a lot of expensive VM-exits. However, your experiences do sound a little bit extreme.