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I have an i7 with 2 physical cores, because of hyper threading Windows 7 reports 4 cores (at least in the Task Manager). My question is, when allocating cores to a VM in VMWare Player is it taking from the pool of 4 hyper threaded cores or simply 2 physical cores?

Strangely it allows me to select up to 8 cores despite only having 2 physical and 4 total with hyper threading on the host.

So if I say, here Mr.VM take 1 core, will it take 1 of the 4 'cores' or 1 of 2 the physical cores? In the first case I would be giving it 1/2 of my cores, in the second I would be giving it 1/4 of my cores if the hyper threaded cores are included in the pool of available cores.

Edit: Here is what the VMWare Player docs say:

Using Virtual Symmetric Multiprocessing

With Virtual Symmetric Multiprocessing (SMP), you can assign up to eight processors to a virtual machine on any host machine that has at least two logical processors.

The following are all considered to have two or more logical processors:

  • A multiprocessor host with two or more physical CPUs
  • A single-processor host with a multicore CPU
  • A single-processor host with hyperthreading enabled

NOTE: On hyperthreaded uniprocessor hosts, performance of virtual machines with Virtual SMP might be below normal. With VMware Player you can power on and run multiple dual-processor virtual machines concurrently.

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In response to your second question:

So if I say, here Mr.VM take 1 core, will it take 1 of the 4 'cores' or 1 of 2 the physical cores?

There is an option when you create the VM and also after you have created it, in the settings panel under Processors in which you specify whether you want to use both processors, or the cores per processor.

Edit by Asker:

This proves that it does indeed take from a pool of the total cores available that includes hyper threaded cores because when I selected 8-cores it gave a warning, but when I selected 4-cores it did not.

The answer: Hyper threaded cores are included in the available cores to be given to the VM.

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In my case, I don't have the ability to use that many cores or processors, but with your CPU, you should be able to do so.

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  • Ok, this DOES answer my question a bit indirectly. The answer to the question is it chooses from a pool of all 4 cores even though 2 of the 4 are hyper threaded and only 2 physical cores exist. The way I am sure of this now is because if I select '8 cores' it tells me that this is not available, but '4 cores' option is no problem. Thanks for hinting me in the right direction.
    – MetaGuru
    Apr 27, 2011 at 18:12

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