Windows XP/Vista/7 x32/x64 for better performance ?

[BeSt]

Hi all,

I want to use (trough Virtualbox) a software that needs mostly CPU and RAM performance, and a bit of HDD performance (DxO Optics actually).
I'm wondering which OS would be better for performance (FYI, I have a Core2 Duo E6420, so sharing 2 cores would be better)

• XP x32 single core, since there is problems with virtualisation of 2 cores on XP x32. My software doesn't seem to run on XP x64
• W7 x64 2 cores
• Vista ? another solution ?

I'm currently running W7 x64 with 2 cores on the VM and my host is Ubuntu 10.10 64bit. I find that the common use is very slow: I found it especially slow when opening/moving windows.
Of course, I've tried to set the better settings (2 cores for the VM, 2 Go shared among 4 Go, using hdd through SATA controllers, 2D and 3D acceleration activated, fixed size disk for the VM, vbox additions installed, VT-x enabled, ...). Or maybe there are some settings in the guest that can improve performance ?

Thank you for your help ! And if any other information is needed please ask.

[Sasquatch]

I have Windows 7 x64 on a VM too with an intel P8750 CPU (HP 6730b laptop). Even though I've only given it 1 CPU, when I open an application, the whole laptop slows to a crawl. Now this is also because the VM only has 512 MB RAM because the Host has just 2 GB, but when I compare it to my PC which has 3 GB of RAM and runs the 32 bit version of W7 with 768 MB RAM, there isn't much difference in excessive I/O. The I/O on the laptop could be because of pagefile use due to low physical RAM, but the PC has enough to run without. Yet it too uses the hard drive a lot.
Windows XP on the PC runs a lot faster the way I experience it. Since I/O generates CPU use too, having a lot of it from W7 is a hit on performance for a CPU intensive application.

With my experiences between W7 and XP, I would go with XP on a single CPU core. If the program can run on both, why run it on a heavier OS?

[BeSt]

The solution is not so easy: with W7, I have the benefit of using 2 cores instead of only 1 with XP.

[Sasquatch]

Maybe, but the CPU has only two cores, so you don't leave one for the Host to work with. The guest can render the Host useless in such case when it goes berserk. I prefer to use the rule "CPUs for VM = Total physical cores - 1". This would mean that a duo core CPU gives just one core to the VM, a quad core can give up to three cores to a VM and a hexacore up to 5. Octacores are not common, but would mean 7 cores for VMs.