libvirt users - Jul 2012 - Matching host and guest CPU

Hi,

I have an fc17 server with an Opteron 6128 with a few fc17/16 guests.
How can I be sure I'm best matching the guest CPU with that of the
server?

I've used virt-manager to create the guests, and it currently shows
the processor is a "Phenom(tm) 9550 Quad-Core":

processor       : 1
vendor_id       : AuthenticAMD
cpu family      : 16
model           : 2
model name      : AMD Phenom(tm) 9550 Quad-Core Processor
stepping        : 3
microcode       : 0x1000065
cpu MHz         : 2000.138
cache size      : 512 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext
fxsr_opt pdpe1gb lm rep_good nopl extd_apicid pni cx16 popcnt
hypervisor lahf_lm cmp_legacy svm cr8_legacy abm sse4a misalignsse
3dnowprefetch npt
bogomips        : 4000.27
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management:

The guests seem to run very slowly, and just wondered if this may be
the cause. Can someone recommend some basic optimizations I may
already be missing from my guest config?

<domain type='kvm'>
  <name>boxtech-new</name>
  <uuid>66887405-a34b-2ec2-1d6c-308aafb1f32e</uuid>
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  <vcpu>2</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.14'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu match='exact'>
    <model>Opteron_G3</model>
    <vendor>AMD</vendor>
    <feature policy='require' name='skinit'/>
    <feature policy='require' name='vme'/>
    <feature policy='require' name='mmxext'/>
    <feature policy='require' name='fxsr_opt'/>
    <feature policy='require' name='cr8legacy'/>
    <feature policy='require' name='ht'/>
    <feature policy='require' name='3dnowprefetch'/>
    <feature policy='require' name='3dnowext'/>
    <feature policy='require' name='wdt'/>
    <feature policy='require' name='extapic'/>
    <feature policy='require' name='pdpe1gb'/>
    <feature policy='require' name='osvw'/>
    <feature policy='require' name='cmp_legacy'/>
    <feature policy='require' name='3dnow'/>
  </cpu>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/boxtech-new.img'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x05'
function='0x0'/>
    </disk>
    <disk type='block' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1'
unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x01'
function='0x1'/>
    </controller>
    <interface type='bridge'>
      <mac address='52:54:00:bc:55:64'/>
      <source bridge='br0'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x03'
function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1'
autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x04'
function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x02'
function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00'
slot='0x06'
function='0x0'/>
    </memballoon>
  </devices>
</domain>

Thanks,
Alex