[CentOS-virt] How many virtual guest 'cpus' can a core duo 'quad' core support

Wed Feb 22 07:14:14 UTC 2012
Trey Dockendorf <treydock at gmail.com>

On Tue, Feb 21, 2012 at 2:59 PM, James B. Byrne <byrnejb at harte-lyne.ca> wrote:
> CentOS-6.2
>
> What is the maximum number of cpus can I configure for a
> single vm guest running on a host with this hardware?
>
> # lscpu
> Architecture:          x86_64
> CPU op-mode(s):        32-bit, 64-bit
> Byte Order:            Little Endian
> CPU(s):                4
> On-line CPU(s) list:   0-3
> Thread(s) per core:    1
> Core(s) per socket:    4
> CPU socket(s):         1
> NUMA node(s):          1
> Vendor ID:             GenuineIntel
> CPU family:            6
> Model:                 23
> Stepping:              10
> CPU MHz:               1998.000
> BogoMIPS:              5331.76
> Virtualization:        VT-x
> L1d cache:             32K
> L1i cache:             32K
> L2 cache:              2048K
> NUMA node0 CPU(s):     0-3
>
> I ask this because it occurs to me that I may have missed
> something fundamental respecting the use of the initialism
> CPU vice the term Cores.
>
>
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The maximum you can assign to a single VM is the amount of CPUs
visible to the KVM host.  So a quad core is shows as 4 CPUs to the OS,
so you could assign 4 vCPUs to a guest.  To see how much is available
and seen by KVM run # virsh nodeinfo.

 - Trey