CPU/Threads/Cores and vCPU relationship and committing

[AVal]

We have a physical machine with 2 cpu's (E5649), each has 6 cores and 2 threads per core (12 threads). The kernel of that physical machine displays the 24 cpu's. On this physical machine, we're running a KVM with 12 Vcpu's and would like to know if we can go to 16 - 18 Vcpu's without any penalty or do we gain any more performance.

Thanks in advance,

[Anonymous]

It is possible to add more vCPUs (threads) to your virtual machine. The virtual machine will handle more applications at the same time and provides with better performance; however, your host computer will lost performance and Threads.