Can hardware virtualisation use threads from processor cores

Question

I have intel i7 processor with 4 physical cores and each one has 2 threads which is total 8 logical cores.

I intent to have virtual machine with windows server that will use all processor potential. While crating virtual machine with VMWare workstation it asks me to set number of processors and number of core per processor, but there is no threads mentioned at all. Is it correct to set number of processors to 4 assuming that processors are cores on i7 and to set number of cores per processor to 2 assuming that it is number of threads per core.

Is this right way of thinking about it? Or, is it even possible to enhance virtual machine with with threads from processor's cores?

Thanks.

Answer 1

This is what is suppose to happen.

Hyperthreading allow your processor to pretend to have X amount of cores. The software will have no idea how many physical cores there are, in general.

Answer 2

If you have Hyperthreading enabled, treat your system as if it has 8 cores.

If you have such strong performance restrictions, that it is not advisable to do that, then disable Hyperthreading and use it like a 4 core system.

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In theory, it is very possible to determine if a given core is physical or not.

If I open Process Explorer on a similar i7 system, I get this result: As we can see, the CPUs are grouped in 4 groups (the physical cores) of 2 members (what was produced by using Hyperthreading).

An application could set its affinity so that it would most optimally use the system (if it is even able to determine that).