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I'd like to install Linux server to virtualbox. I'm running Windows 7 Ultimate x64 as my host.

Should i make my virtual machine x64 or x86? What would have better performance for my host?

x86 probably uses less resources than x64, but x64 is matching my host.


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up vote 2 down vote accepted

x64 should have a better performance but will use slightly more memory.

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You mean better performance on host? So there's some conversion gõing on when running virtual x86 on x64 machine? – Kristian Jul 20 '12 at 8:47
No, there are probably not that much more conversion when the running x86 on x64. I'm just pointing out the 32 bit mode is generally less efficient than the 64 bit mode on the x86 architecture. This is mainly due to the larger number of registers available in 64 bit mode. Note that VirtualBox supports running 64 bit VM on a 32 bit host assuming the physical CPU isn't 32 bit. – jlliagre Jul 20 '12 at 8:52
Thanks for explanation :) Cheers! – Kristian Jul 20 '12 at 8:54
@jlliagre For Virtualbox to support 64-bit guest, the processor must have hardware virtualisation. – kinokijuf Jul 20 '12 at 11:17
@kinokijuf - He makes this perfectly clear read the entire comment, for instance where he said the following "assuming the physical CPU isn't 32 bit" seems pretty clear to me. – Ramhound Jul 20 '12 at 12:00

Choosing x64 or x86 should not make a big difference for your use case (you won't give the VM more than 4GB I guess).

Some points to consider though:

  • x86 allows only a 4GB address space in contrast to x64
  • x64 pointers are 64bit vs. 32bit space even if programs don't need >4GB adressable space
  • your server distro may not be available for 32bit (all servers offer >4GB RAM now and come with 64bit)
  • Linux has recently introduced the x32 ABI (for tiny programs that don't need 4GB address space)
  • x64 offers more registers and a richer instruction set
  • You can only allocate 4GB (3.x GB usable) to your 32bit VM

My suggestion: Use x64 and enjoy the pro's while having only negligible drawbacks.

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