vcpu vs core

[sakurai_tabi]

what's the different to vm

1 vcpu  and 2 core

vs

2 vcpu and 1 core ?

[julienvarela]

In vsphere 5 , you can now create a VM with virtual socket and define a number of cores per socket from the Gui client.

In fact, you have no difference , the only difference is from your guest OS.

If you have a limitation of core per socket, you can add a second virtual socket. But be carefull , somes application are licensed with virtual socket.

Julien.

[ScreamingSilenc]

This KB can help you understand the diff http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=101018...

[vFantastic]

I always use 2cpu/1core to build the VMs as I remember reading somewhere that Windows takes advantage of this better.

[0v3rc10ck3d]

Two separate scenarios, one is your trying to adhere to a licensing restriction per socket or per core.

The other is based off physical CPU cache.  If you select two virtual sockets with one core each your VM will see two one socket CPU's, multi threaded applications will not benefit from the processors onboard cache as it wont leave something from a thread on one core and expect to see it on the other. Whereas if you have if you configure it for a single socket with two cores it will be able to utlize the cache for multi threaded applications.

If you have a machine with two quad cores procs you would want the follow

4 vCPU and under keep it one one socket.

Above 4 vCPU switch it to two sockets.

That way the VM can utilize the cache on the physical CPU and expect to find it.