I am choosing between two models of servers, the major difference between them being the the availability of Hyper-Threading.
The big difference between them is that the first has 4 core/4 threads configuration, while the latter has 4 core/8 threads, due to Hyper-Threading being enabled.
I am going to run CentOS 6 and other OS guests on a CentOS 6 host with KVM virtualization. Currently I assign 1 virtual CPU per virtual machine, as that's enough for my current loads. Our normal load is the usual web services.
How much should the performance differ for me? Is it close to having twice more computing power or nearly the same computing power, distributed over twice more cores?