Issue:
There are times when you might want or need to limit the amount of Physical CPUs (PCPU) presented to ESXi.  It can be either a licensing issue or perhaps you just need to run some testing.  For whatever reason, physically removing the CPUs is not an option so you need a way to tell ESXi to ignore the excess Physical CPUs.

Resolution:

1. Modify the VMkernel.Boot.maxPCPUS setting
2. This is listed under Configuration -> Software -> Advanced Settings ->VMKernel -> Boot
3. The number you put here depends on your configuration.  For instance, if you have a 4 proc by 4 core system and you want to reduce the number of physical processors to 2 and maximize the logical processors, you would put 8 as the number. 2×4.
4. If you have a 4 proc by 2 core system and you want to reduce the number of physical processors to 2 and maximize the logical processors, you would put 4 as the number. 2×2

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