Quad core support for Windows XP guests

Discussions about using Windows guests in VirtualBox.

Quad core support for Windows XP guests

Postby azenz » 7. Aug 2007, 09:26

I am about to buy a quad core system and wonder how many cores a Windows XP system running under Linux (kernel 2.6) can effectively use. If I run video encoding under the virtual XP, how many cores will be utilised (assuming the host system is mostly idle)? If quad core isn't used, will the system at least make use of two cores? Has Innotek run any benchmarks on this?

Really appreciate your answer as that's a really important issue for me. Thanks!

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Postby steqve » 7. Aug 2007, 09:42

A wild guess....but since vbox is scheduled as one process/thread it would only run at one core at the time.

Am I completely wrong here?
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Postby azenz » 7. Aug 2007, 10:57

But the point is that multi-thread apps can make use of several cores even when doing one thing (that's what many video rendering apps can do now), so in theory Virtualbox could run a VM across several cores if it were programmed that way.
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Postby sandervl » 7. Aug 2007, 11:04

There is only one thread that will run guest code for your VM. VirtualBox itself is very multi-threaded. Network, disk and other tasks run in separate threads.
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Postby azenz » 7. Aug 2007, 12:11

Thanks for replying, does that mean that disk operations to virtual disks while running a virtual machine are on a different thread?

Are there any plans to make virtual machines themselves multi-threaded?
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Postby azenz » 7. Aug 2007, 14:57

Oh, does Virtualbox support the Kentsfield Quad Core Virtualization Technology?
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Postby jetteroheller » 13. Aug 2007, 18:58

It seems that the point of all this is that it doesn't. I've been trying to find out if anyone is going to enable such, but at this time it looks like there's no way to get VCPUs running on a guest OS.

My host is Fedora 7, and while I've had great luck with VirtualBox running Vista and Win2003 guests, it's for single-CPU only. For multiple CPUs, I have QEMU running other Linux guests on a F7 host, but have not successfully gotten a Windows guest to run. But in Qemu you can just select how many VCPU's you want to allocate to a guest, and if you have them available, you can use them.
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