On 26.02.2009, at 01:48, Piavlo wrote:
Hi,
I'm new to KVM and have some questions regarding kvm cpu emulation,
hope you can answer them.
I have a kvm node with Dual-Core AMD Opteron(tm) Processor 2218
processors.
1)I was wondering choosing what cpu emulation for VM would give
best performance?
I get the following options
# kvm -cpu ?
x86 qemu64
x86 phenom
x86 core2duo
x86 qemu32
x86 coreduo
x86 486
x86 pentium
x86 pentium2
x86 pentium3
x86 athlon
x86 n270
#
I was thinking one of qemu64/phenom/athlon .
Does It matter what 64bit cpu emulation i choose?
What would be chosen if I omit the -cpu option?
If you omit -cpu it chooses the "qemu64" model, which is the best
choice for most cases. Don't choose anything else if you don't have
any specific reason to do so.
2) I want to optimize/recompile a gentoo VM system packages for the
chosen cpu - if that matters.
Does rebuilding the VM packages to fine tuned for the emulated cpu
give any advantages?
I don't think features like SSE3 matter that much in a normal
environment. You won't get too much more benefit from choosing a
different CPU type.
3) Do I have to boot a VM kernel with guest viritio drivers, to get
a not emulated real cpu access - like I have in Xen?
virtio drivers have nothing to do with CPU. They are about devices
like network and block. If you want to have PV drivers for those, you
need to have a kernel that supports virtio (incl. virtio_pci) and
specify that you want to use virtio on the qemu command line as
options to -net or -drive.
Alex
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