Re: 64 bit guest much faster ?

Gerd Hoffmann
2009-10-26T08:58:47Z

On 10/23/09 17:54, Stefan wrote:
>
> Hello,
>
> I have a simple question (sorry I'm a kvm beginner):
> Is it right that a 64bit guest (8 CPUs, 16GB) is
> much faster than a 32bit guest (8 CPUs, 16GB PAE).
^^^^
Yes. With *that* much memory the 32bit guest struggles with address
space limitations (32bit -> 4G), whereas the 64bit guest doesn't.

With up to 1G you shouldn't see a noticable difference. But the more
highmem the 32bit guest uses the higher is the penalty. Especially
without ept/npt as every kmap() of a high page is a roundtrip to the
hypervisor then.

cheers,
Gerd